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  • 7/26/2019 Claulation for check suitability of IPS

    1/45

    CLIENT:-

    Client: Mundra Port & SEZ.

    Project:- 220/66/11kV Electrical Distribution. Sales Ref.: IS/WR/

    Description:

    Amapacity Calculation of 2" IPS AL Tube.

    (Schedule 40)

    Drawing No.:

    Rev G71000-X0009-ED07

    Chkd. SO

    Date 15.04.2009

    Siemens Ltd

    KG OfficeRemarks Date

    Prep. SGP

    Name

    Busbar Current Rating and BPI Cantilever Calculation 1/45

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    1 Introduction

    A. A rigid bus is supported on bus post insulators in an out-door substation. These bus post insulators are

    subjected to all types of stresses due to electrical and mechanical forces acting on bus bar.

    The principal forces on the bus post insulators supporting a rigid conductor are as follows:

    a. Short circuit force on bus conductor

    b. Wind force on the bus conductor

    c. Wind force on the bus post insulatord. Weight of the bus conductor span supported by the bus post insulators

    The resultant of these forces, correlated to the type of 'end Connection' of the rigid conductor at the bus

    post insulator terminal, gives the values of the net Electromagnetic Force on the bus post insulator. The

    values of forces obtained herewith forms valuable input for the design of bus post insulator support structure

    and its foundation design.

    In this report along with the force on bus post insulators, the maximum permissible unsupported span length

    of the rigid bus conductor connecting the bus post insulators is also determined. The maximum permissible

    span is calculated within the limits of 'Vertical Deflection' and permissible 'Fiber Stress' corresponding to the

    type of 'End Connection' to the supporting bus post insulator terminals at each end of the span. The

    calculation is performed on the method stipulated by IEEE 605 and the minimum of the span length obtained

    from the calculation is conservatively considered as the maximum allowable unsupported span for all

    influencing conditions.

    Busbar Current Rating and BPI Cantilever Calculation 2/45

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    1 Continuous Current Carrying Capacity

    Bus bar continuous rating required Amps.

    As per INDAL handbook current rating (nominal for outdoor) are as below:-

    IPS Aluminum Tube

    - Inches Amps.

    As per INDAL handbook for the maximum operating temperature of the bus to 75 Deg. C, the deratingfactor to be adopted is 0.88; hence the derated current rating (nominal for outdoor) are as below:-

    2 Inches IPS Al Tube - Schedule 40 = 1440 = Amps.

    From the above it is summrised that, for the required current carrying capacity of 875 Amps.,

    2 Inches IPS Al Tube - Schedule 40 is sufficient.

    2 Thermal Effects on IPS Aluminium Tube as per IEEE 605

    Bus Bar Selected Inch

    Ambient temperature in deg. C (T2)

    Final temperature in deg. C (T1)

    2.1 Radiation Loss (Qr)From Stefan-Boltzman law,

    Qr = 36.9 x 10-12

    x e x ( T14-T2

    4) x A (Clause No. 3.2.4, IEEE 605)

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    T1 = Temperature of the bar,oK = + 273 =

    0K

    T2 = Ambient temperature,oK = + 273 =

    0K

    E = Emissivity factor =

    Qr = 36.9 x 10-12

    x 0.6 x (4-

    4) x = Watts/Ft

    2.2 Convective Loss (Qc)

    Heat is dissipated from a tubular bus bar by forced convection

    Heat transfer is considered at wind speed 2 fps and 1 atmospheric pressure.

    Qc = 0.010 x x A (Clause No. 3.2.2, IEEE 605)d

    0.4

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    d = outside diameter of bus bar in inch = Inch

    = Temperature difference between conductor surface & ambient air in deg C = T1 - T2 =

    = - = deg. C

    Qc = 0.010 x x = Watts/Ft

    ( )0.4

    2.3 Heat Gain Due To Solar Radiation (Qs)

    Qs = h x s x d x 12

    h = co-efficient of absorption of conductor surface = 0.5

    s = intensity of solar radiation in Watts/Inch2= Watts/In

    2

    Assumed - 849.27 Watts/Mtr.2

    d = outside diameter of bus bar in inch = Inch

    Qs = 0.5 x 0.5479 x 2.375196 = Watts/Ft

    90.0

    875

    323.0

    2.00

    50.0

    2.38 89.54

    Schedule 40 2.00

    50.0

    1440

    12670.88 x

    40.0

    0.6

    363.0 323.0 89.54

    25.340

    90.0 363.0

    2.375

    0.5479

    2.38 89.54

    89.54

    90.0 50.0 40.0

    2.38

    7.81

    12.8435

    2.38

    Busbar Current Rating and BPI Cantilever Calculation 3/45

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    2.4 Conductor Resistance

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x C' x (T1 - 20) (Clause No. 3.2.9, IEEE 605)

    C' x A2 61

    Rt2 = Direct current resistance at maximum operating temperature

    C' = Conductivity as % IACS =

    A2 = Cross sectional area in In

    d1 = outside diameter of bus bar in inch = Incht = Thickness of tube = Inch

    d2 = inside diameter of bus bar in inch = d1- 2t = - 2 x = Inch

    A2 = (/4) x (d1 -d2 ) = (/4) x ( - ) = In

    T1 = Final temperature in deg. C = deg. C

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x x ( - 20 )

    x

    Rt2 = /Ft

    2.5 Skin Effect Ratio

    0.5

    f = 0.0636 x F (Clause No. 6, IEEE 605)

    r 5280 x Rt2

    f = Skin Effect Ratio

    r = outer diameter / 2 = / 2 = Inch

    F = Frequency In Hz = 50 Hz

    Rt2 = Direct current resistance at maximum operating temperature = / Ft

    f = x 50 0.5

    5280 x

    =

    2.6 Current Rating / Current Carrying Capability

    0.5

    I = Qc + Qr - Qs (Clause No. 3.2, IEEE 605)

    Rt2x f

    0.5

    = + - = Amps.

    x

    61

    90.0

    90.0

    55.0

    0.0636

    1.72924E-05 1.25

    55.0 1.07422

    25.340 12.8435

    1.72924E-05

    2.38

    7.81 1183.91

    2.067

    2.38 2.067 1.07422

    2.38 0.154

    1.187598

    1.72924E-05

    1.25

    1.1876 1.72924E-05

    55.0

    2.380.154

    Busbar Current Rating and BPI Cantilever Calculation 4/45

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    3 Bus Span Calculations For - 2 Inch IPS Aluminium Tube

    Short circuit forces maximum span calculation are as per IEEE 605

    Bus Bar Selected Inches Al Tube

    Bus Bar outer Diameter in Inches

    Bus Bar Cross Section Moment of inertia in cm4

    (J)

    Bus Bar Section modulus in cm3

    (S)

    Bus Bar ultimate tensile strength in Kg/mm2

    (UT)

    Modulus of Elasticity of Busbar in Kg/mm2

    (E)

    Bus bar Unit Self weight in Kgf/mtr (Fc)

    Maximum allowable stress in Kg/mm2

    (Fa)

    Clamping material unit weight in Kgf/mtr (Fd) 7 Kg x 1 Nos. = 0.88

    8.0 mtrs

    Bus Phase to Phase Spacing in Mtrs (D)

    Short Circuit Fault Level in kA (Isc)

    Duration of the short-circuit current in seconds Tk

    Rated short time in seconds Tkr

    Wind Speed In Mtr/sec (V)

    Allowable deflection in inches: 1 time dia of tube

    3.1 Force Due to Wind (Fw)

    Unit force due to wind on conductor is given by

    Fw = C Cd Kz Gf V I (Dia + 2xrI) in Lbf/Ft (Equation No. 9, IEEE 605)

    C = 2.132 x 10-4

    for English units

    Cd = Drag coefficient for smooth tubular conductor = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    Dia = Outer Dia of Conductor in inches = Inch

    I = Importance factor = (Clause No. 9.4, IEEE 605)

    rI = radial ice thickness in Inches = 0 Inch

    Fw = 2.132 x 10-4 x 1 x 1.16 x 0.85 x x x 1.15 x (2.3751968503937 + 2x0)

    = Lbf/Ft = x 1.488 = Kgf/mtr

    3.2 Short Circuit Force (Fsc)

    Short Circuit Force is given by

    Fsc = Kf x C x x (Df x 2 x Isc)2

    (Equation No. 12, IEEE 605)

    D

    C = 5.4 x 10-7

    for English units

    Isc = RMS short circuit current in A kA

    D = Phase to Phase Spacing of Busbars in Inch = x 39.37 = Inch

    = Constant based on type of short circuit & conductor location =

    (Table 2, for 3 phase short circuit on Y phase, IEEE 605)

    Kf = Mounting structure flexibility factor = 1

    (Figure 4, IEEE 605)

    2.00

    2.375

    27.709

    9.186

    0.85

    2

    31.5

    1

    1

    7030.67

    1.871

    20.5

    123.03

    2.375

    1.15

    123.03

    55

    20.5

    1.16

    31.5

    2 78.74

    0.866

    123.03

    8.69 8.69 12.93294

    Busbar Current Rating and BPI Cantilever Calculation 5/45

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    Df = Decrement factor = (Equation No. 11a, IEEE 605)

    Ta = X 1

    R 2 x x fX = System Reactance

    R = System Resistance

    f = System Frequency = 50 Hz

    X =

    RTa = x 1 =

    2 x x 50

    tf = Fault current duration = 1 sec.

    Df =

    Fsc = 1 x 5.4 x 10-7 x 0.866 x ( x 2 x ) = Lbf/Ft

    = x 1.488 = Kgf/mtr

    3.3 Gravitational Forces (Fg)

    Fg = Fc + Fi + Fd (Equation No. 13, IEEE 605)

    Fg = Total bus unit weight in kgf/mtr

    Fc = Conductor unit weight in kgf/mtr =

    Fi = Ice unit weight in kgf/mtr = 0

    Fd = Clamping material unit weight I kgf/mtr =

    Fg = 1.871 + 0 + 0. = kgf/mtr = / 1.488 = Lbf/Ft

    3.4 Total Force (Ft)

    Total force on conductor in Horizontal configuration is given by

    Ft = (Equation No. 22, IEEE 605)

    = ( + )2

    +( )2 = Kgf/mtr

    4 Calculation Of Allowable Spans

    4.1 For continuous bus, the maximum allowable span length based on vertical deflection is (Ld)

    Ld = C x (185 x E x J x Ya)1/4

    (Equation No. 20, IEEE 605)

    Fg

    C = for English units

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/in2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    Ya = Allowable Deflection as vertical dimension of tube = 1D = 1 x = Inch

    Fg = Total bus unit weight in kgf/mtr = Kgf/mtr = x (1/1.488)

    = Lbf/Ft

    Ld = 1.86 x ( 185 x 10000000.03 x 2 )1/4

    = In

    Ld = / 39.37 = Mtrs.

    Hence, maximum allowable span due to vertical deflection is mtrs.

    12.35

    78.74

    15

    15 0.0477

    1.02

    12.35 18.37

    1.871

    0.875

    1.02 31500

    2.746 2.746 1.85

    12.9329 18.37 2.746 31.43

    27.709

    27.709 0.67

    2.000

    1.86

    7031

    7031 1E+07

    0.67 355.52

    1.845

    355.52 9.03

    2.00

    2.746 2.746

    1.85

    9.03

    f

    a

    2t-

    Ta

    f

    T1 + 1 exp

    t

    2 2

    W SC GF F F

    Busbar Current Rating and BPI Cantilever Calculation 6/45

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    4.2 Allowable Span For Fibre Stress (Ls)

    Ls = C x ( (28/3) x Fa x S ) (Equation No. 29c, IEEE 605)

    Ft

    C = for English units

    Fa = Maximum allowable stress in Lbf/In2

    = Kg/mm2

    = x 1422.33 = Lbf/In2

    S = Section modulus in In3

    For Inch Al Tube, S = cm3

    = / 16.3871 = In3

    Ft = Total Force in Lbf/Ft

    = Kgf/mtr = / 1.488 = Lbf/ft

    Ls = 3.46 x ( (28/3) x x ) = Inch

    = / 39.37 = Mtrs.

    5 Conclusion

    As per IEEE 605, page number 25, Clause No. 11.3, the maximum allowable span is the lower of the spans

    as calculated for Ld and Ls.

    The maximum allowable bus span is Mtrs. for Inches Aluminium tube.

    6.1 Natural Frequency of Conductor Span (fb)

    fb = x k2 ( E x J ) (Equation No. 5, IEEE 605)

    C x L2

    m

    C = 24 for English units

    L = Span length in Feet = Mtrs. = / 0.305 = Feet

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/In2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    m = Mass per unit length = Fc = Kgf/mtr = / 1.488 = Lbf/Ft

    k = for two fixed ends

    fb = x ( )2

    ( x ) = Hz

    24 x ( )2

    Twice the calculated natural frequency of the bus span = 2 x = Hz

    6.2 Wind Induced Vibration or Aeolian Force Frequency (fa )

    fa = C x V (Equation No. 6, IEEE 605)

    d

    C = for English units

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    d = Conductor diameter in inches = Inches = x 2.54 = cm

    fa = x = Hz

    As per IEEE 605, page number 10, clause number 7.2.2, if twice the calculated natural frequency of the

    bus span is greater than the Aeolian force frequency, then the bus span should be changed or bus should

    be damped.

    Since, twice the calculated natural frequency of the bus span is Hz, which is less than the

    Aeolian force frequency of Hz, the selected bus span of meters is safe from

    Aeolian vibrations.

    2.0 9.186 9.186 0.56

    3.46

    20.5 20.5 29157.8

    294.1 7.47

    31.43 31.43 21.12

    29157.8 0.56

    7.47 2.00

    7.47 7.47

    294.1

    21.12

    27.709

    27.709 0.67

    1.871 1.871

    24.49

    7031

    7031 1E+07

    2.29

    1.26

    1.51

    1.51 1.150.671E+07

    3.26

    123.03

    2 2

    24.49 1.26

    1.15

    5.08

    2.29

    79.0 7.47

    5.08

    3.26 123.03 79.0

    Busbar Current Rating and BPI Cantilever Calculation 7/45

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    7 Insulator Cantilever Strength Calculation As per IEEE 605

    Effective Bus Span Length in Mtrs (Le) +

    2

    = Mtrs.

    Height of Insulator Stack in mm (Hi)

    Height of Centre Line of Bus over Insulator Height in mm (Hf)

    = / 25.4

    = Inch

    Effective Insulator Diameter in mm (Di) =

    7.1 Force Due To Wind On Bus (Fwb)

    Fwb = Fw x Le (Equation No. 31, IEEE 605)

    Fw = Unit Wind Force On Bus in Lbf/Ft = Lbf/Ft

    Le = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fwb = x = Lbf

    7.2 Bus Short Circuit Force (Fsb)

    Fsb = Fsc x Le (Equation No. 30, IEEE 605)

    Fsc = Unit short circuit force on Bus in Lbf/Ft = Lbf/FtLe = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fsb = x = Lbf

    7.3 Force Due To Wind On Insulator (Fwi)

    Fwi = C x Cd x Kz x Gf x Vx (Di + 2rI) x Hi (Equation No. 32, IEEE 605)

    C = for English units Formula as per IEEE 605, 1987

    Cd = Drag coefficient = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust Factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr Di = Effective Dia of Insulator in Inch = = / 25.4 = Inch

    Hi = Height of insulator in Feet = / (0.305 x 1000) = Feet

    rI = Radial ice thickness in Inch = 0 Inch

    Fwi = 1.776 x 10-5 x 1 x 1.16 x 0.85x ( )2x( + 2x0 ) x

    Fwi = x = Lbf

    7.4 Gravitation Force ( Fgb)

    Fgb = Fg x Le (Equation No. 34, IEEE 605)

    Fg = Total bus unit weight in Lbf/ Ft = Lbf/Ft

    Le = Effective Bus Span Length in feet = x (39.37/12) = Feet

    Fgb = x = Lbf

    80

    80

    3.15

    160

    6 6

    6

    770

    8.69

    6 19.7

    8.69 19.7 171.09

    12.356 19.7

    12.35 19.7 243.09

    160 160 6.30

    770 2.52

    1.776 x 10-5

    1.16

    0.85

    123.03

    19.7

    1.85 19.7 36.33

    123.03 6.30 2.52

    0.00001776 237349 4.21531

    1.85

    6

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    7.5 Insulator Cantilever Load (Fis)

    (Equation No. 35, IEEE 605)

    Fis = K1 x Fwi + ( Hi + Hf ) x Fwb + K2 x ( Hi + Hf ) x Fsb

    2 Hi Hi

    K1 = Overload factor applied to wind forces =

    K2 = Overload factor applied to short-circuit current forces = 1

    1x + ( + ) x ) + 1 x

    ( + ) x = Lbf = x 4.44822

    = Newton

    Hence, Insulators with 4kN cantilever strength is selected.

    1

    4.22 30.31 3.15 171.09

    459.316 459.316

    30.31 2043.14

    2 30.31

    30.31 3.15 243.09

    Busbar Current Rating and BPI Cantilever Calculation 9/45

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    CLIENT:-

    Client: Mundra Port & SEZ.

    Project:- 220/66/11kV Electrical Distribution. Sales Ref.: IS/WR/

    Description:

    Amapacity Calculation of 3" IPS AL Tube.

    (Schedule 40)

    Drawing No.:

    Rev G71000-X0009-ED07Name

    Date 15.04.2009

    Prep. SGP

    Chkd. SO

    Siemens Ltd

    KG OfficeRemarks Date

    Busbar Current Rating and BPI Cantilever Calculation 10/45

  • 7/26/2019 Claulation for check suitability of IPS

    11/45

    1 Introduction

    A. A rigid bus is supported on bus post insulators in an out-door substation. These bus post insulators are

    subjected to all types of stresses due to electrical and mechanical forces acting on bus bar.

    The principal forces on the bus post insulators supporting a rigid conductor are as follows:

    a. Short circuit force on bus conductor

    b. Wind force on the bus conductor

    c. Wind force on the bus post insulatord. Weight of the bus conductor span supported by the bus post insulators

    The resultant of these forces, correlated to the type of 'end Connection' of the rigid conductor at the bus

    post insulator terminal, gives the values of the net Electromagnetic Force on the bus post insulator. The

    values of forces obtained herewith forms valuable input for the design of bus post insulator support structure

    and its foundation design.

    In this report along with the force on bus post insulators, the maximum permissible unsupported span length

    of the rigid bus conductor connecting the bus post insulators is also determined. The maximum permissible

    span is calculated within the limits of 'Vertical Deflection' and permissible 'Fiber Stress' corresponding to the

    type of 'End Connection' to the supporting bus post insulator terminals at each end of the span. The

    calculation is performed on the method stipulated by IEEE 605 and the minimum of the span length obtained

    from the calculation is conservatively considered as the maximum allowable unsupported span for all

    influencing conditions.

    Busbar Current Rating and BPI Cantilever Calculation 11/45

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    1 Continuous Current Carrying Capacity

    Bus bar continuous rating required Amps.

    As per INDAL handbook current rating (nominal for outdoor) are as below:-

    IPS Aluminum Tube

    - Inches Amps.

    As per INDAL handbook for the maximum operating temperature of the bus to 75 Deg. C, the deratingfactor to be adopted is 0.88; hence the derated current rating (nominal for outdoor) are as below:-

    2 Inches IPS Al Tube - Schedule 40 = 1440 = Amps.

    From the above it is summrised that, for the required current carrying capacity of 875 Amps.,

    2 Inches IPS Al Tube - Schedule 40 is sufficient.

    2 Thermal Effects on IPS Aluminium Tube as per IEEE 605

    Bus Bar Selected Inch

    Ambient temperature in deg. C (T2)

    Final temperature in deg. C (T1)

    2.1 Radiation Loss (Qr)From Stefan-Boltzman law,

    Qr = 36.9 x 10-12

    x e x ( T14-T2

    4) x A (Clause No. 3.2.4, IEEE 605)

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    T1 = Temperature of the bar,oK = + 273 =

    0K

    T2 = Ambient temperature,oK = + 273 =

    0K

    E = Emissivity factor =

    Qr = 36.9 x 10-12

    x 0.6 x (4-

    4) x = Watts/Ft

    2.2 Convective Loss (Qc)

    Heat is dissipated from a tubular bus bar by forced convection

    Heat transfer is considered at wind speed 2 fps and 1 atmospheric pressure.

    Qc = 0.010 x x A (Clause No. 3.2.2, IEEE 605)d

    0.4

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    d = outside diameter of bus bar in inch = Inch

    = Temperature difference between conductor surface & ambient air in deg C = T1 - T2 =

    = - = deg. C

    Qc = 0.010 x x = Watts/Ft

    ( )0.4

    2.3 Heat Gain Due To Solar Radiation (Qs)

    Qs = h x s x d x 12

    h = co-efficient of absorption of conductor surface = 0.5

    s = intensity of solar radiation in Watts/Inch2= Watts/In

    2

    Assumed - 849.27 Watts/Mtr.2

    d = outside diameter of bus bar in inch = Inch

    Qs = 0.5 x 0.5479 x 2.375196 = Watts/Ft

    12.8435

    2.38

    2.38

    40.0 25.340

    90.0 363.0

    363.0

    7.81

    323.0 89.54

    2.375

    0.5479

    2.38 89.54

    89.54

    90.0 50.0 40.0

    Schedule 40 2.00 1440

    12670.88 x

    0.6

    89.54

    875

    90.0

    50.0 323.0

    2.00

    50.0

    2.38

    Busbar Current Rating and BPI Cantilever Calculation 12/45

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    2.4 Conductor Resistance

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x C' x (T1 - 20) (Clause No. 3.2.9, IEEE 605)

    C' x A2 61

    Rt2 = Direct current resistance at maximum operating temperature

    C' = Conductivity as % IACS =

    A2 = Cross sectional area in In

    d1 = outside diameter of bus bar in inch = Incht = Thickness of tube = Inch

    d2 = inside diameter of bus bar in inch = d1- 2t = - 2 x = Inch

    A2 = (/4) x (d1 -d2 ) = (/4) x ( - ) = In

    T1 = Final temperature in deg. C = deg. C

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x x ( - 20 )

    x

    Rt2 = /Ft

    2.5 Skin Effect Ratio

    0.5

    f = 0.0636 x F (Clause No. 6, IEEE 605)

    r 5280 x Rt2

    f = Skin Effect Ratio

    r = outer diameter / 2 = / 2 = Inch

    F = Frequency In Hz = 50 Hz

    Rt2 = Direct current resistance at maximum operating temperature = / Ft

    f = x 50 0.5

    5280 x

    =

    2.6 Current Rating / Current Carrying Capability

    0.5

    I = Qc + Qr - Qs (Clause No. 3.2, IEEE 605)

    Rt2x f

    0.5

    = + - = Amps.

    x

    1.1876 1.72924E-05

    55.0

    2.380.154

    2.067

    2.38 2.067 1.07422

    2.38 0.154

    1.72924E-05

    1.187598

    1183.91

    0.0636

    1.72924E-05 1.25

    1.25

    61

    90.0

    55.0 1.07422

    25.340 12.8435

    1.72924E-05

    2.38

    7.81

    90.0

    55.0

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    3 Bus Span Calculations For - 2 Inch IPS Aluminium Tube

    Short circuit forces maximum span calculation are as per IEEE 605

    Bus Bar Selected Inches Al Tube

    Bus Bar outer Diameter in Inches

    Bus Bar Cross Section Moment of inertia in cm4

    (J)

    Bus Bar Section modulus in cm3

    (S)

    Bus Bar ultimate tensile strength in Kg/mm2

    (UT)

    Modulus of Elasticity of Busbar in Kg/mm2

    (E)

    Bus bar Unit Self weight in Kgf/mtr (Fc)

    Maximum allowable stress in Kg/mm2

    (Fa)

    Clamping material unit weight in Kgf/mtr (Fd) 7 Kg x 1 Nos. = 0.88

    8.0 mtrs

    Bus Phase to Phase Spacing in Mtrs (D)

    Short Circuit Fault Level in kA (Isc)

    Duration of the short-circuit current in seconds Tk

    Rated short time in seconds Tkr

    Wind Speed In Mtr/sec (V)

    Allowable deflection in inches: 1 time dia of tube

    3.1 Force Due to Wind (Fw)

    Unit force due to wind on conductor is given by

    Fw = C Cd Kz Gf V I (Dia + 2xrI) in Lbf/Ft (Equation No. 9, IEEE 605)

    C = 2.132 x 10-4

    for English units

    Cd = Drag coefficient for smooth tubular conductor = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    Dia = Outer Dia of Conductor in inches = Inch

    I = Importance factor = (Clause No. 9.4, IEEE 605)

    rI = radial ice thickness in Inches = 0 Inch

    Fw = 2.132 x 10-4 x 1 x 1.16 x 0.85 x x x 1.15 x (2.3751968503937 + 2x0)

    = Lbf/Ft = x 1.488 = Kgf/mtr

    3.2 Short Circuit Force (Fsc)

    Short Circuit Force is given by

    Fsc = Kf x C x x (Df x 2 x Isc)2

    (Equation No. 12, IEEE 605)

    D

    C = 5.4 x 10-7

    for English units

    Isc = RMS short circuit current in A kA

    D = Phase to Phase Spacing of Busbars in Inch = x 39.37 = Inch

    = Constant based on type of short circuit & conductor location =

    (Table 2, for 3 phase short circuit on Y phase, IEEE 605)

    Kf = Mounting structure flexibility factor = 1

    (Figure 4, IEEE 605)

    31.5

    2 78.74

    0.866

    123.03

    2.375

    1.15

    123.03 123.03

    8.69 8.69 12.93294

    55

    20.5

    1.16

    0.85

    2

    31.5

    1

    1

    7030.67

    1.871

    20.5

    2.00

    2.375

    27.709

    9.186

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    Df = Decrement factor = (Equation No. 11a, IEEE 605)

    Ta = X 1

    R 2 x x fX = System Reactance

    R = System Resistance

    f = System Frequency = 50 Hz

    X =

    RTa = x 1 =

    2 x x 50

    tf = Fault current duration = 1 sec.

    Df =

    Fsc = 1 x 5.4 x 10-7 x 0.866 x ( x 2 x ) = Lbf/Ft

    = x 1.488 = Kgf/mtr

    3.3 Gravitational Forces (Fg)

    Fg = Fc + Fi + Fd (Equation No. 13, IEEE 605)

    Fg = Total bus unit weight in kgf/mtr

    Fc = Conductor unit weight in kgf/mtr =

    Fi = Ice unit weight in kgf/mtr = 0

    Fd = Clamping material unit weight I kgf/mtr =

    Fg = 1.871 + 0 + 0. = kgf/mtr = / 1.488 = Lbf/Ft

    3.4 Total Force (Ft)

    Total force on conductor in Horizontal configuration is given by

    Ft = (Equation No. 22, IEEE 605)

    = ( + )2

    +( )2 = Kgf/mtr

    4 Calculation Of Allowable Spans

    4.1 For continuous bus, the maximum allowable span length based on vertical deflection is (Ld)

    Ld = C x (185 x E x J x Ya)1/4

    (Equation No. 20, IEEE 605)

    Fg

    C = for English units

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/in2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    Ya = Allowable Deflection as vertical dimension of tube = 1D = 1 x = Inch

    Fg = Total bus unit weight in kgf/mtr = Kgf/mtr = x (1/1.488)

    = Lbf/Ft

    Ld = 1.86 x ( 185 x 10000000.03 x 2 )1/4

    = In

    Ld = / 39.37 = Mtrs.

    Hence, maximum allowable span due to vertical deflection is mtrs.

    1.845

    355.52 9.03

    9.03

    2.000 2.00

    2.746 2.746

    1.85

    0.67 355.52

    1.86

    7031

    7031 1E+07

    27.709

    27.709 0.67

    1.871

    0.875

    2.746 2.746 1.85

    12.9329 18.37 2.746 31.43

    1.02

    1.02 31500 12.35

    78.74

    12.35 18.37

    15

    15 0.0477

    f

    a

    2t-

    Ta

    f

    T1 + 1 exp

    t

    2 2

    W SC GF F F

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    4.2 Allowable Span For Fibre Stress (Ls)

    Ls = C x ( (28/3) x Fa x S ) (Equation No. 29c, IEEE 605)

    Ft

    C = for English units

    Fa = Maximum allowable stress in Lbf/In2

    = Kg/mm2

    = x 1422.33 = Lbf/In2

    S = Section modulus in In3

    For Inch Al Tube, S = cm3

    = / 16.3871 = In3

    Ft = Total Force in Lbf/Ft

    = Kgf/mtr = / 1.488 = Lbf/ft

    Ls = 3.46 x ( (28/3) x x ) = Inch

    = / 39.37 = Mtrs.

    5 Conclusion

    As per IEEE 605, page number 25, Clause No. 11.3, the maximum allowable span is the lower of the spans

    as calculated for Ld and Ls.

    The maximum allowable bus span is Mtrs. for Inches Aluminium tube.

    6.1 Natural Frequency of Conductor Span (fb)

    fb = x k2 ( E x J ) (Equation No. 5, IEEE 605)

    C x L2

    m

    C = 24 for English units

    L = Span length in Feet = Mtrs. = / 0.305 = Feet

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/In2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    m = Mass per unit length = Fc = Kgf/mtr = / 1.488 = Lbf/Ft

    k = for two fixed ends

    fb = x ( )2

    ( x ) = Hz

    24 x ( )2

    Twice the calculated natural frequency of the bus span = 2 x = Hz

    6.2 Wind Induced Vibration or Aeolian Force Frequency (fa )

    fa = C x V (Equation No. 6, IEEE 605)

    d

    C = for English units

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    d = Conductor diameter in inches = Inches = x 2.54 = cm

    fa = x = Hz

    As per IEEE 605, page number 10, clause number 7.2.2, if twice the calculated natural frequency of the

    bus span is greater than the Aeolian force frequency, then the bus span should be changed or bus should

    be damped.

    Since, twice the calculated natural frequency of the bus span is Hz, which is less than the

    Aeolian force frequency of Hz, the selected bus span of meters is safe from

    Aeolian vibrations.

    5.08

    2.29

    79.0 7.47

    2 2 5.08

    3.26 123.03 79.0

    24.49 1.26

    1.15 2.29

    3.26

    123.03

    1.26

    1.51

    1.51 1.150.671E+07

    7031 1E+07

    27.709

    27.709 0.67

    1.871 1.871

    7.47 2.00

    7.47 7.47 24.49

    7031

    29157.8 0.56 294.1

    21.12

    294.1 7.47

    2.0 9.186 9.186 0.56

    31.43 31.43 21.12

    3.46

    20.5 20.5 29157.8

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    7 Insulator Cantilever Strength Calculation As per IEEE 605

    Effective Bus Span Length in Mtrs (Le) +

    2

    = Mtrs.

    Height of Insulator Stack in mm (Hi)

    Height of Centre Line of Bus over Insulator Height in mm (Hf)

    = / 25.4

    = Inch

    Effective Insulator Diameter in mm (Di) =

    7.1 Force Due To Wind On Bus (Fwb)

    Fwb = Fw x Le (Equation No. 31, IEEE 605)

    Fw = Unit Wind Force On Bus in Lbf/Ft = Lbf/Ft

    Le = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fwb = x = Lbf

    7.2 Bus Short Circuit Force (Fsb)

    Fsb = Fsc x Le (Equation No. 30, IEEE 605)

    Fsc = Unit short circuit force on Bus in Lbf/Ft = Lbf/FtLe = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fsb = x = Lbf

    7.3 Force Due To Wind On Insulator (Fwi)

    Fwi = C x Cd x Kz x Gf x Vx (Di + 2rI) x Hi (Equation No. 32, IEEE 605)

    C = for English units Formula as per IEEE 605, 1987

    Cd = Drag coefficient = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust Factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr Di = Effective Dia of Insulator in Inch = = / 25.4 = Inch

    Hi = Height of insulator in Feet = / (0.305 x 1000) = Feet

    rI = Radial ice thickness in Inch = 0 Inch

    Fwi = 1.776 x 10-5 x 1 x 1.16 x 0.85x ( )2x( + 2x0 ) x

    Fwi = x = Lbf

    7.4 Gravitation Force ( Fgb)

    Fgb = Fg x Le (Equation No. 34, IEEE 605)

    Fg = Total bus unit weight in Lbf/ Ft = Lbf/Ft

    Le = Effective Bus Span Length in feet = x (39.37/12) = Feet

    Fgb = x = Lbf

    0.00001776 237349 4.21531

    1.85

    1.85 19.7 36.33

    6 19.7

    6.30

    770 2.52

    123.03 6.30 2.52

    1.776 x 10-5

    1.16

    0.85

    123.03160 160

    12.356 19.7

    12.35 19.7 243.09

    8.69

    6 19.7

    8.69 19.7 171.09

    6

    770

    80

    80

    3.15

    160

    6 6

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    7.5 Insulator Cantilever Load (Fis)

    (Equation No. 35, IEEE 605)

    Fis = K1 x Fwi + ( Hi + Hf ) x Fwb + K2 x ( Hi + Hf ) x Fsb

    2 Hi Hi

    K1 = Overload factor applied to wind forces =

    K2 = Overload factor applied to short-circuit current forces = 1

    1x + ( + ) x ) + 1 x

    ( + ) x = Lbf = x 4.44822

    = Newton

    Hence, Insulators with 4kN cantilever strength is selected.

    459.316

    30.31 2043.14

    2 30.31

    30.31 3.15 243.09 459.316

    1

    4.22 30.31 3.15 171.09

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    CLIENT:-

    Client: Mundra Port & SEZ.

    Project:- 220/66/11kV Electrical Distribution. Sales Ref.: IS/

    Description:

    Amapacity Calculation of 3" IPS AL Tube.

    (Schedule 40)

    Drawing No.:

    Rev G71000-X0009-ED07Name

    Date 15.04.2009

    Prep. SGP

    Chkd. SO

    Siemens Ltd

    KG OfficeRemarks Date

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    1 Introduction

    A. A rigid bus is supported on bus post insulators in an out-door substation. These bus post insulators are

    subjected to all types of stresses due to electrical and mechanical forces acting on bus bar.

    The principal forces on the bus post insulators supporting a rigid conductor are as follows:

    a. Short circuit force on bus conductor

    b. Wind force on the bus conductor

    c. Wind force on the bus post insulatord. Weight of the bus conductor span supported by the bus post insulators

    The resultant of these forces, correlated to the type of 'end Connection' of the rigid conductor at the bus

    post insulator terminal, gives the values of the net Electromagnetic Force on the bus post insulator. The

    values of forces obtained herewith forms valuable input for the design of bus post insulator support structure

    and its foundation design.

    In this report along with the force on bus post insulators, the maximum permissible unsupported span length

    of the rigid bus conductor connecting the bus post insulators is also determined. The maximum permissible

    span is calculated within the limits of 'Vertical Deflection' and permissible 'Fiber Stress' corresponding to the

    type of 'End Connection' to the supporting bus post insulator terminals at each end of the span. The

    calculation is performed on the method stipulated by IEEE 605 and the minimum of the span length obtained

    from the calculation is conservatively considered as the maximum allowable unsupported span for all

    influencing conditions.

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    2 Continuous Current Carrying Capacity

    Bus bar continuous rating required Amps.

    As per INDAL handbook current rating (nominal for outdoor) are as below:-

    IPS Aluminum Tube

    - Inches Amps.

    As per INDAL handbook for the maximum operating temperature of the bus to 75 Deg. C, the deratingfactor to be adopted is 0.88; hence the derated current rating (nominal for outdoor) are as below:-

    3 Inches IPS Al Tube - Schedule 40 = 2350 = Amps.

    From the above it is summrised that, for the required current carrying capacity of 263 Amps.,

    3 Inches IPS Al Tube - Schedule 40 is sufficient.

    3 Thermal Effects on IPS Aluminium Tube as per IEEE 605

    Bus Bar Selected Inch

    Ambient temperature in deg. C (T2)

    Final temperature in deg. C (T1)

    3.1 Radiation Loss (Qr)From Stefan-Boltzman law,

    Qr = 36.9 x 10-12

    x e x ( T14-T2

    4) x A (Clause No. 3.2.4, IEEE 605)

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    T1 = Temperature of the bar,oK = + 273 =

    0K

    T2 = Ambient temperature,oK = + 273 =

    0K

    E = Emissivity factor =

    Qr = 36.9 x 10-12

    x 0.6 x (4-

    4) x = Watts/Ft

    3.2 Convective Loss (Qc)

    Heat is dissipated from a tubular bus bar by forced convection

    Heat transfer is considered at wind speed 2 fps and 1 atmospheric pressure.

    Qc = 0.010 x x A (Clause No. 3.2.2, IEEE 605)d

    0.4

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    d = outside diameter of bus bar in inch = Inch

    = Temperature difference between conductor surface & ambient air in deg C = T1 - T2 =

    = - = deg. C

    Qc = 0.010 x x = Watts/Ft

    ( )0.4

    3.3 Heat Gain Due To Solar Radiation (Qs)

    Qs = h x s x d x 12

    h = co-efficient of absorption of conductor surface = 0.5

    s = intensity of solar radiation in Watts/Inch2= Watts/In

    2

    Assumed - 849.27 Watts/Mtr.2

    d = outside diameter of bus bar in inch = Inch

    Qs = 0.5 x 0.5479 x 3.5 x 12 = Watts/Ft

    18.9258

    3.50

    3.50

    40.0 31.977

    90.0 363.0

    363.0

    11.51

    323.0 131.95

    3.500

    0.5479

    3.50 131.95

    131.95

    90.0 50.0 40.0

    Schedule 40 3.00 2350

    20680.88 x

    0.6

    131.95

    263

    90.0

    50.0 323.0

    3.00

    50.0

    3.50

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    3.4 Conductor Resistance

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x C' x (T1 - 20) (Clause No. 3.2.9, IEEE 605)

    C' x A2 61

    Rt2 = Direct current resistance at maximum operating temperature

    C' = Conductivity as % IACS =

    A2 = Cross sectional area in In

    d1 = outside diameter of bus bar in inch = Incht = Thickness of tube = Inch

    d2 = inside diameter of bus bar in inch = d1- 2t = - 2 x = Inch

    A2 = (/4) x (d1 -d2 ) = (/4) x ( - ) = In

    T1 = Final temperature in deg. C = deg. C

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x x ( - 20 )

    x

    Rt2 = /Ft

    3.5 Skin Effect Ratio

    0.5

    f = 0.0636 x F (Clause No. 6, IEEE 605)

    r 5280 x Rt2

    f = Skin Effect Ratio

    r = outer diameter / 2 = / 2 = Inch

    F = Frequency In Hz = 50 Hz

    Rt2 = Direct current resistance at maximum operating temperature = / Ft

    f = x 50 0.5

    5280 x

    =

    3.6 Current Rating / Current Carrying Capability

    0.5

    I = Qc + Qr - Qs (Clause No. 3.2, IEEE 605)

    Rt2x f

    0.5

    = + - = Amps.

    x

    1.75 8.33058E-06

    55.0

    3.500.216

    3.068

    3.50 3.068 2.22984

    3.50 0.216

    8.33058E-06

    1.75

    1964.56

    0.0636

    8.33058E-06 1.23

    1.23

    61

    90.0

    55.0 2.22984

    31.977 18.9258

    8.33058E-06

    3.50

    11.51

    90.0

    55.0

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    4 Bus Span Calculations For - 3 Inch IPS Aluminium Tube

    Short circuit forces maximum span calculation are as per IEEE 605

    Bus Bar Selected Inches Al Tube

    Bus Bar outer Diameter in Inches

    Bus Bar Cross Section Moment of inertia in cm4

    (J)

    Bus Bar Section modulus in cm3

    (S)

    Bus Bar ultimate tensile strength in Kg/mm2

    (UT)

    Modulus of Elasticity of Busbar in Kg/mm2

    (E)

    Bus bar Unit Self weight in Kgf/mtr (Fc)

    Maximum allowable stress in Kg/mm2

    (Fa)

    Clamping material unit weight in Kgf/mtr (Fd) 7 Kg x 1 Nos. = 0.58

    12.0 mtrs

    Bus Phase to Phase Spacing in Mtrs (D)

    Short Circuit Fault Level in kA (Isc)

    Duration of the short-circuit current in seconds Tk

    Rated short time in seconds Tkr

    Wind Speed In Mtr/sec (V)

    Allowable deflection in inches: 1 time dia of tube

    4.1 Force Due to Wind (Fw)

    Unit force due to wind on conductor is given by

    Fw = C Cd Kz Gf V I (Dia + 2xrI) in Lbf/Ft (Equation No. 9, IEEE 605)

    C = 2.132 x 10-4

    for English units

    Cd = Drag coefficient for smooth tubular conductor = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    Dia = Outer Dia of Conductor in inches = Inch

    I = Importance factor = (Clause No. 9.4, IEEE 605)

    rI = radial ice thickness in Inches = 0 Inch

    Fw = 2.132 x 10-4 x 1 x 1.16 x 0.85 x x x 1.15 x (3.5 + 2x0)

    = Lbf/Ft = x 1.488 = Kgf/mtr

    4.2 Short Circuit Force (Fsc)

    Short Circuit Force is given by

    Fsc = Kf x C x x (Df x 2 x Isc)2

    (Equation No. 12, IEEE 605)

    D

    C = 5.4 x 10-7

    for English units

    Isc = RMS short circuit current in A kA

    D = Phase to Phase Spacing of Busbars in Inch = x 39.37 = Inch

    = Constant based on type of short circuit & conductor location =

    (Table 2, for 3 phase short circuit on Y phase, IEEE 605)

    Kf = Mounting structure flexibility factor = 1

    (Figure 4, IEEE 605)

    40

    4.25 167.32

    0.866

    123.03

    3.500

    1.15

    123.03 123.03

    12.81 12.81 19.05748

    55

    20.5

    1.16

    0.85

    4.25

    40

    1

    1

    7030.67

    3.884

    20.5

    3.00

    3.500

    125.606

    28.258

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    Df = Decrement factor = (Equation No. 11a, IEEE 605)

    Ta = X 1

    R 2 x x fX = System Reactance

    R = System Resistance

    f = System Frequency = 50 Hz

    X =

    RTa = x 1 =

    2 x x 50

    tf = Fault current duration = 1 sec.

    Df =

    Fsc = 1 x 5.4 x 10-7 x 0.866 x ( x 2 x ) = Lbf/Ft

    = x 1.488 = Kgf/mtr

    4.3 Gravitational Forces (Fg)

    Fg = Fc + Fi + Fd (Equation No. 13, IEEE 605)

    Fg = Total bus unit weight in kgf/mtr

    Fc = Conductor unit weight in kgf/mtr =

    Fi = Ice unit weight in kgf/mtr = 0

    Fd = Clamping material unit weight I kgf/mtr =

    Fg = 3.884 + 0 + 0. = kgf/mtr = / 1.488 = Lbf/Ft

    4.4 Total Force (Ft)

    Total force on conductor in Horizontal configuration is given by

    Ft = (Equation No. 22, IEEE 605)

    = ( + )2

    +( )2 = Kgf/mtr

    5 Calculation Of Allowable Spans

    5.1 For continuous bus, the maximum allowable span length based on vertical deflection is (Ld)

    Ld = C x (185 x E x J x Ya)1/4

    (Equation No. 20, IEEE 605)

    Fg

    C = for English units

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/in2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    Ya = Allowable Deflection as vertical dimension of tube = 1D = 1 x = Inch

    Fg = Total bus unit weight in kgf/mtr = Kgf/mtr = x (1/1.488)

    = Lbf/Ft

    Ld = 1.86 x ( 185 x 10000000.03 x 3 )1/4

    = In

    Ld = / 39.37 = Mtrs.

    Hence, maximum allowable span due to vertical deflection is mtrs.

    3.002

    508.33 12.91

    12.91

    3.000 3.00

    4.467 4.467

    3.00

    3.02 508.33

    1.86

    7031

    7031 1E+07

    125.606

    125.606 3.02

    3.884

    0.583333

    4.467 4.467 3.00

    19.0575 13.94 4.467 33.30

    1.02

    1.02 40000 9.37

    167.32

    9.37 13.94

    15

    15 0.0477

    f

    a

    2t-

    Ta

    f

    T1 + 1 exp

    t

    2 2

    W SC GF F F

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    5.2 Allowable Span For Fibre Stress (Ls)

    Ls = C x ( (28/3) x Fa x S ) (Equation No. 29c, IEEE 605)

    Ft

    C = for English units

    Fa = Maximum allowable stress in Lbf/In2

    = Kg/mm2

    = x 1422.33 = Lbf/In2

    S = Section modulus in In3

    For Inch Al Tube, S = cm3

    = / 16.3871 = In3

    Ft = Total Force in Lbf/Ft

    = Kgf/mtr = / 1.488 = Lbf/ft

    Ls = 3.46 x ( (28/3) x x ) = Inch

    = / 39.37 = Mtrs.

    6 Conclusion

    As per IEEE 605, page number 25, Clause No. 11.3, the maximum allowable span is the lower of the spans

    as calculated for Ld and Ls.

    The maximum allowable bus span is Mtrs. for Inches Aluminium tube.

    7.1 Natural Frequency of Conductor Span (fb)

    fb = x k2 ( E x J ) (Equation No. 5, IEEE 605)

    C x L2

    m

    C = 24 for English units

    L = Span length in Feet = Mtrs. = / 0.305 = Feet

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/In2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    m = Mass per unit length = Fc = Kgf/mtr = / 1.488 = Lbf/Ft

    k = for two fixed ends

    fb = x ( )2

    ( x ) = Hz

    24 x ( )2

    Twice the calculated natural frequency of the bus span = 2 x = Hz

    7.2 Wind Induced Vibration or Aeolian Force Frequency (fa )

    fa = C x V (Equation No. 6, IEEE 605)

    d

    C = for English units

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    d = Conductor diameter in inches = Inches = x 2.54 = cm

    fa = x = Hz

    As per IEEE 605, page number 10, clause number 7.2.2, if twice the calculated natural frequency of the

    bus span is greater than the Aeolian force frequency, then the bus span should be changed or bus should

    be damped.

    Since, twice the calculated natural frequency of the bus span is Hz, which is less than the

    Aeolian force frequency of Hz, the selected bus span of meters is safe from

    Aeolian vibrations.

    7.62

    1.17

    52.6 12.73

    3 3 7.62

    3.26 123.03 52.6

    41.72 2.61

    0.58 1.17

    3.26

    123.03

    2.61

    1.51

    1.51 0.583.021E+07

    7031 1E+07

    125.606

    125.606 3.02

    3.884 3.884

    12.73 3.00

    12.73 12.73 41.72

    7031

    29157.8 1.72 501.0

    22.38

    501.0 12.73

    3.0 28.258 28.258 1.72

    33.30 33.30 22.38

    3.46

    20.5 20.5 29157.8

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    8 Insulator Cantilever Strength Calculation As per IEEE 605

    Effective Bus Span Length in Mtrs (Le) +

    2

    = Mtrs.

    Height of Insulator Stack in mm (Hi)

    Height of Centre Line of Bus over Insulator Height in mm (Hf)

    = / 25.4

    = Inch

    Effective Insulator Diameter in mm (Di) =

    8.1 Force Due To Wind On Bus (Fwb)

    Fwb = Fw x Le (Equation No. 31, IEEE 605)

    Fw = Unit Wind Force On Bus in Lbf/Ft = Lbf/Ft

    Le = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fwb = x = Lbf

    8.2 Bus Short Circuit Force (Fsb)

    Fsb = Fsc x Le (Equation No. 30, IEEE 605)

    Fsc = Unit short circuit force on Bus in Lbf/Ft = Lbf/FtLe = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fsb = x = Lbf

    8.3 Force Due To Wind On Insulator (Fwi)

    Fwi = C x Cd x Kz x Gf x Vx (Di + 2rI) x Hi (Equation No. 32, IEEE 605)

    C = for English units Formula as per IEEE 605, 1987

    Cd = Drag coefficient = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust Factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr Di = Effective Dia of Insulator in Inch = = / 25.4 = Inch

    Hi = Height of insulator in Feet = / (0.305 x 1000) = Feet

    rI = Radial ice thickness in Inch = 0 Inch

    Fwi = 1.776 x 10-5 x 1 x 1.16 x 0.85x ( )2x( + 2x0 ) x

    Fwi = x = Lbf

    8.4 Gravitation Force ( Fgb)

    Fgb = Fg x Le (Equation No. 34, IEEE 605)

    Fg = Total bus unit weight in Lbf/ Ft = Lbf/Ft

    Le = Effective Bus Span Length in feet = x (39.37/12) = Feet

    Fgb = x = Lbf

    0.00001776 1307151 23.215

    3.00

    3.00 37.7 113.27

    11.5 37.7

    11.61

    2300 7.54

    123.03 11.61 7.54

    1.776 x 10-5

    1.16

    0.85

    123.03295 295

    9.3711.5 37.7

    9.37 37.7 353.55

    12.81

    11.5 37.7

    12.81 37.7 483.22

    11.5

    2300

    130

    130

    5.12

    295

    11.5 11.5

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    8.5 Insulator Cantilever Load (Fis)

    (Equation No. 35, IEEE 605)

    Fis = K1 x Fwi + ( Hi + Hf ) x Fwb + K2 x ( Hi + Hf ) x Fsb

    2 Hi Hi

    K1 = Overload factor applied to wind forces =

    K2 = Overload factor applied to short-circuit current forces = 1

    1x + ( + ) x ) + 1 x

    ( + ) x = Lbf = x 4.44822

    = Newton

    Hence, Insulators with 4kN cantilever strength is selected.

    895.668

    90.55 3984.13

    2 90.55

    90.55 5.12 353.55 895.668

    1

    23.22 90.55 5.12 483.22

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    28/45

    CLIENT:-

    Client: Mundra Port & SEZ.

    Project:- 220/66/11kV Electrical Distribution. Sales Ref.: IS/

    Description:

    Amapacity Calculation of 4" IPS AL Tube.

    (Schedule 40)

    Drawing No.:

    Rev G71000-X0009-ED07

    Chkd. SO

    Date 15.04.2009

    Siemens Ltd

    KG OfficeRemarks Date

    Prep. SGP

    Name

    Busbar Current Rating and BPI Cantilever Calculation 28/45

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    29/45

    1 Introduction

    A. A rigid bus is supported on bus post insulators in an out-door substation. These bus post insulators are

    subjected to all types of stresses due to electrical and mechanical forces acting on bus bar.

    The principal forces on the bus post insulators supporting a rigid conductor are as follows:

    a. Short circuit force on bus conductor

    b. Wind force on the bus conductor

    c. Wind force on the bus post insulatord. Weight of the bus conductor span supported by the bus post insulators

    The resultant of these forces, correlated to the type of 'end Connection' of the rigid conductor at the bus

    post insulator terminal, gives the values of the net Electromagnetic Force on the bus post insulator. The

    values of forces obtained herewith forms valuable input for the design of bus post insulator support structure

    and its foundation design.

    In this report along with the force on bus post insulators, the maximum permissible unsupported span length

    of the rigid bus conductor connecting the bus post insulators is also determined. The maximum permissible

    span is calculated within the limits of 'Vertical Deflection' and permissible 'Fiber Stress' corresponding to the

    type of 'End Connection' to the supporting bus post insulator terminals at each end of the span. The

    calculation is performed on the method stipulated by IEEE 605 and the minimum of the span length obtained

    from the calculation is conservatively considered as the maximum allowable unsupported span for all

    influencing conditions.

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    2 Continuous Current Carrying Capacity

    Bus bar continuous rating required Amps.

    As per INDAL handbook current rating (nominal for outdoor) are as below:-

    IPS Aluminum Tube

    - Inches Amps.

    As per INDAL handbook for the maximum operating temperature of the bus to 75 Deg. C, the deratingfactor to be adopted is 0.88; hence the derated current rating (nominal for outdoor) are as below:-

    4 Inches IPS Al Tube - Schedule 40 = 3050 = Amps.

    From the above it is summrised that, for the required current carrying capacity of 1250 Amps.,

    4 Inches IPS Al Tube - Schedule 40 is sufficient.

    3 Thermal Effects on IPS Aluminium Tube as per IEEE 605

    Bus Bar Selected Inch

    Ambient temperature in deg. C (T2)

    Final temperature in deg. C (T1)

    3.1 Radiation Loss (Qr)From Stefan-Boltzman law,

    Qr = 36.9 x 10-12

    x e x ( T14-T2

    4) x A (Clause No. 3.2.4, IEEE 605)

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    T1 = Temperature of the bar,oK = + 273 =

    0K

    T2 = Ambient temperature,oK = + 273 =

    0K

    E = Emissivity factor =

    Qr = 36.9 x 10-12

    x 0.6 x (4-

    4) x = Watts/Ft

    3.2 Convective Loss (Qc)

    Heat is dissipated from a tubular bus bar by forced convection

    Heat transfer is considered at wind speed 2 fps and 1 atmospheric pressure.

    Qc = 0.010 x x A (Clause No. 3.2.2, IEEE 605)d

    0.4

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    d = outside diameter of bus bar in inch = Inch

    = Temperature difference between conductor surface & ambient air in deg C = T1 - T2 =

    = - = deg. C

    Qc = 0.010 x x = Watts/Ft

    ( )0.4

    3.3 Heat Gain Due To Solar Radiation (Qs)

    Qs = h x s x d x 12

    h = co-efficient of absorption of conductor surface = 0.5

    s = intensity of solar radiation in Watts/Inch2= Watts/In

    2

    Assumed - 849.27 Watts/Mtr.2

    d = outside diameter of bus bar in inch = Inch

    Qs = 0.5 x 0.5479 x 4.5 x 12 = Watts/Ft

    95.0

    1250

    318.0

    4.00

    45.0

    4.50 169.65

    Schedule 40 4.00

    45.0

    3050

    26840.88 x

    50.0

    0.6

    368.0 318.0 169.65

    46.476

    95.0 368.0

    4.500

    0.5479

    4.50 169.65

    169.65

    95.0 45.0 50.0

    4.50

    14.79

    30.4744

    4.50

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    3.4 Conductor Resistance

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x C' x (T1 - 20) (Clause No. 3.2.9, IEEE 605)

    C' x A2 61

    Rt2 = Direct current resistance at maximum operating temperature

    C' = Conductivity as % IACS =

    A2 = Cross sectional area in In

    d1 = outside diameter of bus bar in inch = Incht = Thickness of tube = Inch

    d2 = inside diameter of bus bar in inch = d1- 2t = - 2 x = Inch

    A2 = (/4) x (d1 -d2 ) = (/4) x ( - ) = In

    T1 = Final temperature in deg. C = deg. C

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x x ( - 20 )

    x

    Rt2 = /Ft

    3.5 Skin Effect Ratio

    0.5

    f = 0.0636 x F (Clause No. 6, IEEE 605)

    r 5280 x Rt2

    f = Skin Effect Ratio

    r = outer diameter / 2 = / 2 = Inch

    F = Frequency In Hz = 50 Hz

    Rt2 = Direct current resistance at maximum operating temperature = / Ft

    f = x 50 0.5

    5280 x

    =

    3.6 Current Rating / Current Carrying Capability

    0.5

    I = Qc + Qr - Qs (Clause No. 3.2, IEEE 605)

    Rt2x f

    0.5

    = + - = Amps.

    x

    61

    95.0

    95.0

    55.0

    0.0636

    5.93699E-06 1.13

    55.0 3.17415

    46.476 30.4744

    5.93699E-06

    4.50

    14.79 3045.32

    4.026

    4.50 4.026 3.17415

    4.50 0.237

    2.25

    5.93699E-06

    1.13

    2.25 5.93699E-06

    55.0

    4.500.237

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    4 Bus Span Calculations For - 4 Inch IPS Aluminium Tube

    Short circuit forces maximum span calculation are as per IEEE 605

    Bus Bar Selected Inches Al Tube

    Bus Bar outer Diameter in Inches

    Bus Bar Cross Section Moment of inertia in cm4

    (J)

    Bus Bar Section modulus in cm3

    (S)

    Bus Bar ultimate tensile strength in Kg/mm2

    (UT)

    Modulus of Elasticity of Busbar in Kg/mm2

    (E)

    Bus bar Unit Self weight in Kgf/mtr (Fc)

    Maximum allowable stress in Kg/mm2

    (Fa)

    Clamping material unit weight in Kgf/mtr (Fd) 7 Kg x 1 Nos. = 0.58

    12.0 mtrs

    Bus Phase to Phase Spacing in Mtrs (D)

    Short Circuit Fault Level in kA (Isc)

    Duration of the short-circuit current in seconds Tk

    Rated short time in seconds Tkr

    Wind Speed In Mtr/sec (V)

    Allowable deflection in inches: 1 time dia of tube

    4.1 Force Due to Wind (Fw)

    Unit force due to wind on conductor is given by

    Fw = C Cd Kz Gf V I (Dia + 2xrI) in Lbf/Ft (Equation No. 9, IEEE 605)

    C = 2.132 x 10-4

    for English units

    Cd = Drag coefficient for smooth tubular conductor = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    Dia = Outer Dia of Conductor in inches = Inch

    I = Importance factor = (Clause No. 9.4, IEEE 605)

    rI = radial ice thickness in Inches = 0 Inch

    Fw = 2.132 x 10-4 x 1 x 1.16 x 0.85 x x x 1.15 x (4.5 + 2x0)

    = Lbf/Ft = x 1.488 = Kgf/mtr

    4.2 Short Circuit Force (Fsc)

    Short Circuit Force is given by

    Fsc = Kf x C x x (Df x 2 x Isc)2

    (Equation No. 12, IEEE 605)

    D

    C = 5.4 x 10-7

    for English units

    Isc = RMS short circuit current in A kA

    D = Phase to Phase Spacing of Busbars in Inch = x 39.37 = Inch

    = Constant based on type of short circuit & conductor location =

    (Table 2, for 3 phase short circuit on Y phase, IEEE 605)

    Kf = Mounting structure flexibility factor = 1

    (Figure 4, IEEE 605)

    4.00

    4.500

    301.039

    52.675

    0.85

    3

    40

    3

    3

    7030.67

    5.529

    20.5

    123.03

    4.500

    1.15

    123.03

    55

    20.5

    1.16

    40

    3 118.11

    0.866

    123.03

    16.47 16.47 24.50248

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    Df = Decrement factor = (Equation No. 11a, IEEE 605)

    Ta = X 1

    R 2 x x fX = System Reactance

    R = System Resistance

    f = System Frequency = 50 Hz

    X =

    RTa = x 1 =

    2 x x 50

    tf = Fault current duration = 3 sec.

    Df =

    Fsc = 1 x 5.4 x 10-7 x 0.866 x ( x 2 x ) = Lbf/Ft

    = x 1.488 = Kgf/mtr

    4.3 Gravitational Forces (Fg)

    Fg = Fc + Fi + Fd (Equation No. 13, IEEE 605)

    Fg = Total bus unit weight in kgf/mtr

    Fc = Conductor unit weight in kgf/mtr =

    Fi = Ice unit weight in kgf/mtr = 0

    Fd = Clamping material unit weight I kgf/mtr =

    Fg = 5.529 + 0 + 0. = kgf/mtr = / 1.488 = Lbf/Ft

    4.4 Total Force (Ft)

    Total force on conductor in Horizontal configuration is given by

    Ft = (Equation No. 22, IEEE 605)

    = ( + )2

    +( )2 = Kgf/mtr

    5 Calculation Of Allowable Spans

    5.1 For continuous bus, the maximum allowable span length based on vertical deflection is (Ld)

    Ld = C x (185 x E x J x Ya)1/4

    (Equation No. 20, IEEE 605)

    Fg

    C = for English units

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/in2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    Ya = Allowable Deflection as vertical dimension of tube = 1D = 1 x = Inch

    Fg = Total bus unit weight in kgf/mtr = Kgf/mtr = x (1/1.488)

    = Lbf/Ft

    Ld = 1.86 x ( 185 x 10000000.03 x 4 )1/4

    = In

    Ld = / 39.37 = Mtrs.

    Hence, maximum allowable span due to vertical deflection is mtrs.

    12.87

    118.11

    15

    15 0.0477

    1.01

    12.87 19.15

    5.529

    0.583333

    1.01 40000

    6.112 6.112 4.11

    24.5025 19.15 6.112 44.08

    301.039

    301.039 7.23

    4.000

    1.86

    7031

    7031 1E+07

    7.23 628.41

    4.108

    628.41 15.96

    4.00

    6.112 6.112

    4.11

    15.96

    f

    a

    2t-

    Ta

    f

    T1 + 1 exp

    t

    2 2

    W SC GF F F

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    5.2 Allowable Span For Fibre Stress (Ls)

    Ls = C x ( (28/3) x Fa x S ) (Equation No. 29c, IEEE 605)

    Ft

    C = for English units

    Fa = Maximum allowable stress in Lbf/In2

    = Kg/mm2

    = x 1422.33 = Lbf/In2

    S = Section modulus in In3

    For Inch Al Tube, S = cm3

    = / 16.3871 = In3

    Ft = Total Force in Lbf/Ft

    = Kgf/mtr = / 1.488 = Lbf/ft

    Ls = 3.46 x ( (28/3) x x ) = Inch

    = / 39.37 = Mtrs.

    6 Conclusion

    As per IEEE 605, page number 25, Clause No. 11.3, the maximum allowable span is the lower of the spans

    as calculated for Ld and Ls.

    The maximum allowable bus span is Mtrs. for Inches Aluminium tube.

    7.1 Natural Frequency of Conductor Span (fb)

    fb = x k2 ( E x J ) (Equation No. 5, IEEE 605)

    C x L2

    m

    C = 24 for English units

    L = Span length in Feet = Mtrs. = / 0.305 = Feet

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/In2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    m = Mass per unit length = Fc = Kgf/mtr = / 1.488 = Lbf/Ft

    k = for two fixed ends

    fb = x ( )2

    ( x ) = Hz

    24 x ( )2

    Twice the calculated natural frequency of the bus span = 2 x = Hz

    7.2 Wind Induced Vibration or Aeolian Force Frequency (fa )

    fa = C x V (Equation No. 6, IEEE 605)

    d

    C = for English units

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    d = Conductor diameter in inches = Inches = x 2.54 = cm

    fa = x = Hz

    As per IEEE 605, page number 10, clause number 7.2.2, if twice the calculated natural frequency of the

    bus span is greater than the Aeolian force frequency, then the bus span should be changed or bus should

    be damped.

    Since, twice the calculated natural frequency of the bus span is Hz, which is less than the

    Aeolian force frequency of Hz, the selected bus span of meters is safe from

    Aeolian vibrations.

    4.0 52.675 52.675 3.21

    3.46

    20.5 20.5 29157.8

    594.6 15.10

    44.08 44.08 29.62

    29157.8 3.21

    15.10 4.00

    15.10 15.10

    594.6

    29.62

    301.039

    301.039 7.23

    5.529 5.529

    49.51

    7031

    7031 1E+07

    1.07

    3.72

    1.51

    1.51 0.547.231E+07

    3.26

    123.03

    4 4

    49.51 3.72

    0.54

    10.16

    1.07

    39.5 15.10

    10.16

    3.26 123.03 39.5

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    8 Insulator Cantilever Strength Calculation As per IEEE 605

    Effective Bus Span Length in Mtrs (Le) +

    2

    = Mtrs.

    Height of Insulator Stack in mm (Hi)

    Height of Centre Line of Bus over Insulator Height in mm (Hf)

    = / 25.4

    = Inch

    Effective Insulator Diameter in mm (Di) =

    8.1 Force Due To Wind On Bus (Fwb)

    Fwb = Fw x Le (Equation No. 31, IEEE 605)

    Fw = Unit Wind Force On Bus in Lbf/Ft = Lbf/Ft

    Le = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fwb = x = Lbf

    8.2 Bus Short Circuit Force (Fsb)

    Fsb = Fsc x Le (Equation No. 30, IEEE 605)

    Fsc = Unit short circuit force on Bus in Lbf/Ft = Lbf/FtLe = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fsb = x = Lbf

    8.3 Force Due To Wind On Insulator (Fwi)

    Fwi = C x Cd x Kz x Gf x Vx (Di + 2rI) x Hi (Equation No. 32, IEEE 605)

    C = for English units Formula as per IEEE 605, 1987

    Cd = Drag coefficient = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust Factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr Di = Effective Dia of Insulator in Inch = = / 25.4 = Inch

    Hi = Height of insulator in Feet = / (0.305 x 1000) = Feet

    rI = Radial ice thickness in Inch = 0 Inch

    Fwi = 1.776 x 10-5 x 1 x 1.16 x 0.85x ( )2x( + 2x0 ) x

    Fwi = x = Lbf

    8.4 Gravitation Force ( Fgb)

    Fgb = Fg x Le (Equation No. 34, IEEE 605)

    Fg = Total bus unit weight in Lbf/ Ft = Lbf/Ft

    Le = Effective Bus Span Length in feet = x (39.37/12) = Feet

    Fgb = x = Lbf

    172

    172

    6.77

    182

    12 12

    12

    1472

    16.47

    12 39.4

    16.47 39.4 648.29

    12.8712 39.4

    12.87 39.4 506.75

    182 182 7.17

    1472 4.83

    1.776 x 10-5

    1.16

    0.85

    123.03

    39.4

    4.11 39.4 161.72

    123.03 7.17 4.83

    0.00001776 516125 9.16639

    4.11

    12

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    8.5 Insulator Cantilever Load (Fis)

    (Equation No. 35, IEEE 605)

    Fis = K1 x Fwi + ( Hi + Hf ) x Fwb + K2 x ( Hi + Hf ) x Fsb

    2 Hi Hi

    K1 = Overload factor applied to wind forces =

    K2 = Overload factor applied to short-circuit current forces = 1

    1x + ( + ) x ) + 1 x

    ( + ) x = Lbf = x 4.44822

    = Newton

    Hence, Insulators with 4kN cantilever strength is selected.

    1

    9.17 57.95 6.77 648.29

    1294.6 1294.6

    57.95 5758.66

    2 57.95

    57.95 6.77 506.75

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    CLIENT:-

    Client: Mundra Port & SEZ.

    Project:- 220/66/11kV Electrical Distribution. Sales Ref.: IS/WR

    Description:

    Amapacity Calculation of 4.5" IPS AL Tube.

    (Schedule 40)

    Drawing No.:

    Rev G71000-X0009-ED07Name

    Date 15.04.2009

    Prep. SGP

    Chkd. SO

    Siemens Ltd

    KG OfficeRemarks Date

    Busbar Current Rating and BPI Cantilever Calculation 37/45

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    1 Introduction

    A. A rigid bus is supported on bus post insulators in an out-door substation. These bus post insulators are

    subjected to all types of stresses due to electrical and mechanical forces acting on bus bar.

    The principal forces on the bus post insulators supporting a rigid conductor are as follows:

    a. Short circuit force on bus conductor

    b. Wind force on the bus conductor

    c. Wind force on the bus post insulatord. Weight of the bus conductor span supported by the bus post insulators

    The resultant of these forces, correlated to the type of 'end Connection' of the rigid conductor at the bus

    post insulator terminal, gives the values of the net Electromagnetic Force on the bus post insulator. The

    values of forces obtained herewith forms valuable input for the design of bus post insulator support structure

    and its foundation design.

    In this report along with the force on bus post insulators, the maximum permissible unsupported span length

    of the rigid bus conductor connecting the bus post insulators is also determined. The maximum permissible

    span is calculated within the limits of 'Vertical Deflection' and permissible 'Fiber Stress' corresponding to the

    type of 'End Connection' to the supporting bus post insulator terminals at each end of the span. The

    calculation is performed on the method stipulated by IEEE 605 and the minimum of the span length obtained

    from the calculation is conservatively considered as the maximum allowable unsupported span for all

    influencing conditions.

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    2 Continuous Current Carrying Capacity

    Bus bar continuous rating required Amps.

    As per INDAL handbook current rating (nominal for outdoor) are as below:-

    IPS Aluminum Tube

    - Inches Amps.

    As per INDAL handbook for the maximum operating temperature of the bus to 75 Deg. C, the deratingfactor to be adopted is 0.88; hence the derated current rating (nominal for outdoor) are as below:-

    4.5 Inches IPS Al Tube - Schedule 40 = 3420 = Amps.

    From the above it is summrised that, for the required current carrying capacity of 1250 Amps.,

    4.5 Inches IPS Al Tube - Schedule 40 is sufficient.

    3 Thermal Effects on IPS Aluminium Tube as per IEEE 605

    Bus Bar Selected Inch

    Ambient temperature in deg. C (T2)

    Final temperature in deg. C (T1)

    3.1 Radiation Loss (Qr)From Stefan-Boltzman law,

    Qr = 36.9 x 10-12

    x e x ( T14-T2

    4) x A (Clause No. 3.2.4, IEEE 605)

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    T1 = Temperature of the bar,oK = + 273 =

    0K

    T2 = Ambient temperature,oK = + 273 =

    0K

    E = Emissivity factor =

    Qr = 36.9 x 10-12

    x 0.6 x (4-

    4) x = Watts/Ft

    3.2 Convective Loss (Qc)

    Heat is dissipated from a tubular bus bar by forced convection

    Heat transfer is considered at wind speed 2 fps and 1 atmospheric pressure.

    Qc = 0.010 x x A (Clause No. 3.2.2, IEEE 605)d

    0.4

    A = Surface area = 12 x d x = 12 x x = In2/Ft

    d = outside diameter of bus bar in inch = Inch

    = Temperature difference between conductor surface & ambient air in deg C = T1 - T2 =

    = - = deg. C

    Qc = 0.010 x x = Watts/Ft

    ( )0.4

    3.3 Heat Gain Due To Solar Radiation (Qs)

    Qs = h x s x d x 12

    h = co-efficient of absorption of conductor surface = 0.5

    s = intensity of solar radiation in Watts/Inch2= Watts/In

    2

    Assumed - 849.27 Watts/Mtr.2

    d = outside diameter of bus bar in inch = Inch

    Qs = 0.5 x 0.5479 x 5 x 12 = Watts/Ft

    27.0368

    5.00

    5.00

    40.0 39.607

    90.0 363.0

    363.0

    16.44

    323.0 188.50

    5.000

    0.5479

    5.00 188.50

    188.50

    90.0 50.0 40.0

    Schedule 40 4.50 3420

    30100.88 x

    0.6

    188.50

    1250

    90.0

    50.0 323.0

    4.50

    50.0

    5.00

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    3.4 Conductor Resistance

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x C' x (T1 - 20) (Clause No. 3.2.9, IEEE 605)

    C' x A2 61

    Rt2 = Direct current resistance at maximum operating temperature

    C' = Conductivity as % IACS =

    A2 = Cross sectional area in In

    d1 = outside diameter of bus bar in inch = Incht = Thickness of tube = Inch

    d2 = inside diameter of bus bar in inch = d1- 2t = - 2 x = Inch

    A2 = (/4) x (d1 -d2 ) = (/4) x ( - ) = In

    T1 = Final temperature in deg. C = deg. C

    Rt2 = 8.145 x 10-

    x 1 + 0.00403 x x ( - 20 )

    x

    Rt2 = /Ft

    3.5 Skin Effect Ratio

    0.5

    f = 0.0636 x F (Clause No. 6, IEEE 605)

    r 5280 x Rt2

    f = Skin Effect Ratio

    r = outer diameter / 2 = / 2 = Inch

    F = Frequency In Hz = 50 Hz

    Rt2 = Direct current resistance at maximum operating temperature = / Ft

    f = x 50 0.5

    5280 x

    =

    3.6 Current Rating / Current Carrying Capability

    0.5

    I = Qc + Qr - Qs (Clause No. 3.2, IEEE 605)

    Rt2x f

    0.5

    = + - = Amps.

    x

    2.5 5.03945E-06

    55.0

    5.000.247

    4.506

    5.00 4.506 3.68608

    5.00 0.247

    5.03945E-06

    2.5

    3005.68

    0.0636

    5.03945E-06 1.10

    1.10

    61

    90.0

    55.0 3.68608

    39.607 27.0368

    5.03945E-06

    5.00

    16.44

    90.0

    55.0

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    Df = Decrement factor = (Equation No. 11a, IEEE 605)

    Ta = X 1

    R 2 x x fX = System Reactance

    R = System Resistance

    f = System Frequency = 50 Hz

    X =

    RTa = x 1 =

    2 x x 50

    tf = Fault current duration = 1 sec.

    Df =

    Fsc = 1 x 5.4 x 10-7 x 0.866 x ( x 2 x ) = Lbf/Ft

    = x 1.488 = Kgf/mtr

    4.3 Gravitational Forces (Fg)

    Fg = Fc + Fi + Fd (Equation No. 13, IEEE 605)

    Fg = Total bus unit weight in kgf/mtr

    Fc = Conductor unit weight in kgf/mtr =

    Fi = Ice unit weight in kgf/mtr = 0

    Fd = Clamping material unit weight I kgf/mtr =

    Fg = 6.423 + 0 + 0. = kgf/mtr = / 1.488 = Lbf/Ft

    4.4 Total Force (Ft)

    Total force on conductor in Horizontal configuration is given by

    Ft = (Equation No. 22, IEEE 605)

    = ( + )2

    +( )2 = Kgf/mtr

    5 Calculation Of Allowable Spans

    5.1 For continuous bus, the maximum allowable span length based on vertical deflection is (Ld)

    Ld = C x (185 x E x J x Ya)1/4

    (Equation No. 20, IEEE 605)

    Fg

    C = for English units

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/in2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    Ya = Allowable Deflection as vertical dimension of tube = 1D = 1 x = Inch

    Fg = Total bus unit weight in kgf/mtr = Kgf/mtr = x (1/1.488)

    = Lbf/Ft

    Ld = 1.86 x ( 185 x 10000000.03 x 4.5 )1/4

    = In

    Ld = / 39.37 = Mtrs.

    Hence, maximum allowable span due to vertical deflection is mtrs.

    4.887

    679.30 17.25

    17.25

    4.500 4.50

    7.271 7.271

    4.89

    10.44 679.30

    1.86

    7031

    7031 1E+07

    434.683

    434.683 10.44

    6.423

    0.848485

    7.271 7.271 4.89

    27.225 13.94 7.271 41.81

    1.02

    1.02 40000 9.37

    167.32

    9.37 13.94

    15

    15 0.0477

    f

    a

    2t-

    Ta

    f

    T1 + 1 exp

    t

    2 2

    W SC GF F F

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    5.2 Allowable Span For Fibre Stress (Ls)

    Ls = C x ( (28/3) x Fa x S ) (Equation No. 29c, IEEE 605)

    Ft

    C = for English units

    Fa = Maximum allowable stress in Lbf/In2

    = Kg/mm2

    = x 1422.33 = Lbf/In2

    S = Section modulus in In3

    For Inch Al Tube, S = cm3

    = / 16.3871 = In3

    Ft = Total Force in Lbf/Ft

    = Kgf/mtr = / 1.488 = Lbf/ft

    Ls = 3.46 x ( (28/3) x x ) = Inch

    = / 39.37 = Mtrs.

    6 Conclusion

    As per IEEE 605, page number 25, Clause No. 11.3, the maximum allowable span is the lower of the spans

    as calculated for Ld and Ls.

    The maximum allowable bus span is Mtrs. for Inches Aluminium tube.

    7.1 Natural Frequency of Conductor Span (fb)

    fb = x k2 ( E x J ) (Equation No. 5, IEEE 605)

    C x L2

    m

    C = 24 for English units

    L = Span length in Feet = Mtrs. = / 0.305 = Feet

    E = Modulus of Elasticity in Lbf/In2

    = Kgf/mm2

    = x 1422.34 = Lbf/In2

    J = Cross sectional moment of inertia in In4

    = cm4

    = x (1 / 41.623) = In4

    m = Mass per unit length = Fc = Kgf/mtr = / 1.488 = Lbf/Ft

    k = for two fixed ends

    fb = x ( )2

    ( x ) = Hz

    24 x ( )2

    Twice the calculated natural frequency of the bus span = 2 x = Hz

    7.2 Wind Induced Vibration or Aeolian Force Frequency (fa )

    fa = C x V (Equation No. 6, IEEE 605)

    d

    C = for English units

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr

    d = Conductor diameter in inches = Inches = x 2.54 = cm

    fa = x = Hz

    As per IEEE 605, page number 10, clause number 7.2.2, if twice the calculated natural frequency of the

    bus span is greater than the Aeolian force frequency, then the bus span should be changed or bus should

    be damped.

    Since, twice the calculated natural frequency of the bus span is Hz, which is less than the

    Aeolian force frequency of Hz, the selected bus span of meters is safe from

    Aeolian vibrations.

    11.43

    0.92

    35.1 17.25

    4.5 4.5 11.43

    3.26 123.03 35.1

    56.57 4.32

    0.46 0.92

    3.26

    123.03

    4.32

    1.51

    1.51 0.4610.441E+07

    7031 1E+07

    434.683

    434.683 10.44

    6.423 6.423

    17.25 4.50

    17.25 17.25 56.57

    7031

    29157.8 4.18 696.0

    28.10

    696.0 17.68

    4.5 68.454 68.454 4.18

    41.81 41.81 28.10

    3.46

    20.5 20.5 29157.8

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    8 Insulator Cantilever Strength Calculation As per IEEE 605

    Effective Bus Span Length in Mtrs (Le) +

    2

    = Mtrs.

    Height of Insulator Stack in mm (Hi)

    Height of Centre Line of Bus over Insulator Height in mm (Hf)

    = / 25.4

    = Inch

    Effective Insulator Diameter in mm (Di) =

    8.1 Force Due To Wind On Bus (Fwb)

    Fwb = Fw x Le (Equation No. 31, IEEE 605)

    Fw = Unit Wind Force On Bus in Lbf/Ft = Lbf/Ft

    Le = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fwb = x = Lbf

    8.2 Bus Short Circuit Force (Fsb)

    Fsb = Fsc x Le (Equation No. 30, IEEE 605)

    Fsc = Unit short circuit force on Bus in Lbf/Ft = Lbf/FtLe = Effective Bus Span Length in Feet = x (39.37/12) = Feet

    Fsb = x = Lbf

    8.3 Force Due To Wind On Insulator (Fwi)

    Fwi = C x Cd x Kz x Gf x Vx (Di + 2rI) x Hi (Equation No. 32, IEEE 605)

    C = for English units Formula as per IEEE 605, 1987

    Cd = Drag coefficient = 1 (Table 1, IEEE 605)

    Kz = Height & Exposure factor = (Clause No. 9.2, for category D, IEEE 605)

    Gf = Gust Factor = (Clause No. 9.3, for category C&D, IEEE 605)

    V = Wind speed in Miles/hr

    = 55 x ( 1/ 0.44704) = Miles/hr Di = Effective Dia of Insulator in Inch = = / 25.4 = Inch

    Hi = Height of insulator in Feet = / (0.305 x 1000) = Feet

    rI = Radial ice thickness in Inch = 0 Inch

    Fwi = 1.776 x 10-5 x 1 x 1.16 x 0.85x ( )2x( + 2x0 ) x

    Fwi = x = Lbf

    8.4 Gravitation Force ( Fgb)

    Fgb = Fg x Le (Equation No. 34, IEEE 605)

    Fg = Total bus unit weight in Lbf/ Ft = Lbf/Ft

    Le = Effective Bus Span Length in feet = x (39.37/12) = Feet

    Fgb = x = Lbf

    0.00001776 1307151 23.215

    4.89

    4.89 54.1 264.54

    16.5 54.1

    11.61

    2300 7.54

    123.03 11.61 7.54

    1.776 x 10-5

    1.16

    0.85

    123.03295 295

    9.3716.5 54.1

    9.37 54.1 507.26

    18.30

    16.5 54.1

    18.30 54.1 990.45

    16.5

    2300

    130

    130

    5.12

    295

    16.5 16.5

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    8.5 Insulator Cantilever Load (Fis)

    (Equation No. 35, IEEE 605)

    Fis = K1 x Fwi + ( Hi + Hf ) x Fwb + K2 x ( Hi + Hf ) x Fsb

    2 Hi Hi

    K1 = Overload factor applied to wind forces =

    K2 = Overload factor applied to short-circuit current forces = 1

    1x + ( + ) x ) + 1 x

    ( + ) x = Lbf = x 4.44822

    = Newton

    Hence, Insulators with 8kN cantilever strength is selected.

    1593.97

    90.55 7090.34

    2 90.55

    90.55 5.12 507.26 1593.97

    1

    23.22 90.55 5.12 990.45