how to be successful in drive application · · 2015-12-03how to be successful in drive...

Successful VFD Application

www.tmeic.com Slide 1

How to Be Successful

In VFD Application

How to Be Successful in

Drive Application

Bill Horvath, PE

TMEIC Corporation

Roanoke, VA 24153

Mining Electrical Maintenance Association [MEMSA]

June 2015 Technical Symposium

Clearwater, Florida




In VFD Application

How to Be Successful in

Drive Application




In VFD Application

MV AC VFD and Motor System




In VFD Application

VFD System Considerations

Must consider the whole system in which the

VFD will work

From Utility to finished product or process

Consider environment

Consider effects on utility

Consider the needs of the load

Consider the effect on motors and load




In VFD Application

A VFD Pictorial Overview




In VFD Application

VFD Overall Success Factors 1. Minimum first cost, including installation

2. Maximum long-term payback.

3. Good match to process & loads.

4. Long equipment life.

5. Ease of use for operators & technicians.

6. Minimum impact on nearby equipment.

7. Easy to maintain & repair.




In VFD Application

Relation to Overall Success Factors

Application factors can be grouped

into two major areas:

Electrical/Load Application Factors

Design & Installation Factors




In VFD Application

Electrical/Power Application Factors

Continuous kW or HP & duty cycle

Torque & Power Overload Requirements

Load factors: CT, VT, CHP, regenerative,

non-regenerative.

Drive and Motor Voltage

Power system compatibility, efficiency




In VFD Application

Solution Process Start At Ends

and Work Towards the Middle

#2 - Define the

power system

and requirements

#1 - Define the

process loads

and duty cycle

#3

Determine best

drive solution!




In VFD Application

Know Your Drive Load

Torque loading vs RPM

Regen vs non regen

Continuous operating

points needed

Peak torque needed to

break load away

Load inertia

Speed-time ramps for

accel & decel

Motor

Drive type

Motor thermal rating, Drive

size

Motor starting/breakdown

torque rating, Drive Type

& OL Rating

Drive Tuning & stability

Drive settings

LOAD FACTOR AFFECTS




In VFD Application

Conveyor or Mill Loading

Typical Induction Motor Char on 60 Hz power

TO

RQ

UE

FREQ, SPEED

BREAKAWAY

TORQUE




In VFD Application

Conveyor or Mill Loading

Typical Induction Motor Char on 60 Hz power

TO

RQ

UE

FREQ, SPEED

BREAKAWAY

TORQUE

VFD CONTROLLED MOTOR -

ENOUGH TORQUE ACROSS THE RANGE

A

B C

D

Maximum

Continuous

Power Point

Max

Continuous

Power

Intermediate

Continuous

Power Points




In VFD Application

Continuous Power Requirements

Continuous Power

Needs Set Size of Power Delivery

Transformers

Drive and internal

transformer

Motor

Gearbox




In VFD Application

Peak Torque Requirements

Peak Torque Needs

Affect the Size of Inverter [Switches,

diodes, capacitors]

Sensors

Motor

Gearbox




In VFD Application

Duty Cycle Example

Horsepower = Torque x RPM / 5252

High torque at low speed = low HP

0

2.0

1.0

0

1.0

0.5

60

Torque

Speed [RPM]

Horsepower

0

1.0

0.5

120 180 240 240 300 360

TIME IN SECONDS >

One duty cycle >




In VFD Application

Duty Cycle Calculations

1. Gather information on load torque, HP and speed vs. time

2. Lay out in time sequence

3. Break up into segments

4. Square HP values and get HP2 sec values

5. Sum and take square root

6. Result is RMS HP for motor, drive, and power delivery sizing




In VFD Application

Drive Ratings and Torques

Variable Torque [VT] ratings usually include 110 -115% OL rating

for 60 seconds when starting from rated Temp

Constant Torque [CT] rating usually includes 150% OL rating for

60 seconds when starting from rated Temp.




In VFD Application

Variable Torque Curve

0

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

100.00%

% Speed

Load Torque Varies as the Square of the Speed

Motor Horsepower varies as the Cube of the Speed




In VFD Application

Drive Ratings and Torques

Variable Torque [VT] ratings usually include 110 -115% OL rating

for 60 seconds when starting from rated Temp

Constant Torque [CT] rating usually includes 150% OL rating for

60 seconds when starting from rated Temp.




In VFD Application

Torque Curves Variable vs Constant Torque

Characterized load curves that looks like:

C o n s t a n t T o r q u e L o a d , E x a m p l e 2

C o n s t a n t T o r q u e L o a d , E x a m p l e 1

R P M - - >

L o

a d

T o

r q u

e

T h e o r e t i c a l M o t o r C a p a b i l i t y 1 0 0 % L o a d P o i n t ,

N P R P M , S i n e w a v e p o w e r

i m c a p a b 1 . d r w J u n e 4 , 9 8




In VFD Application

Load mass or inertia requires torque in opposite direction of RPM

Torque x RPM = Negative

Power Flows from motor (now acting as a generator)

Examples:

Stopping a fan

Downhill conveyor

Lowering a load on a crane

Drive converter design must accept power in reverse direction

Active front end

Diode fed will not regenerate

Motoring

Motoring

Regen

(+) Torque

(-) Torque

(+)

RP

M

(-)

RP

M

Q3

Q1 Q2

Q4 Regen

S T

S T

S T

S T

Regenerative Loads




In VFD Application

Weve looked at the process loads, now lets

look at how to power the loads . . . . . . . .

#2 - Define the

power system

and requirements

#1 - Define the

process loads

and duty cycle

#3

Determine best

drive solution!




In VFD Application

Power System Compatibility Including

Power distribution (available

utilization voltages)

Protection.

Harmonics limits.

Power factor control.

Efficiency.




In VFD Application

Power System Compatibility

Breakers, transformers, and cable must be rated to carry full kVA &

harmonics. Selecting higher capacity utilization voltages may

reduce drives impact on the customers power grid.

Transformers need to be drive isolation rated with proper

considerations for the drive type.

Protective devices & settings consider harmonics and drive characteristics.




In VFD Application

Power Line Harmonics

Harmonics are voltages and currents at frequencies that are multiples of utility power frequency.

Harmonic currents are drawn by loads such as drives, computers and ballasts that take their power in non-sine-wave format. These are so-called non-linear loads.

-1.5

-1

-0.5

0

0.5

1

1.5

0 120 240 360

Fundamental, 5th and 7th Harmonics

Sum

Fundamental

7th5th




In VFD Application

Power Line Harmonics

Harmonics from drives can excite other parts of the system and

cause damage

Over-voltages on un-tuned PF caps

High currents due to parallel resonance

Equipment problems may be minimized by reducing

harmonics using:

Filters & Tuned PF correction.

Multi-pulse rectifier drives.




In VFD Application

IEEE 519-1992 Table 10.3 ITDD Limits

Maximum Harmonic Curent Distortion in % of I-Load

Isc to I-load

Ratio h < 11

h = 11

to




In VFD Application

Power System & Drive Efficiency

Drive itself is typically 98% or more efficient

With all fans, transformers, etc, efficiencies of 96-

97% are common

Efficiency impact of drive varies with speed

Efficiency effect of the drive can be eliminated

at full speed by synchronous bypass.




In VFD Application

Example Efficiency Data DB5i MV, Including Transformers & Fans

Calculated Dura-Bilt5 MV Inverter Performance,

500 HP Constant Torque Load

0.00

0.20

0.40

0.60

0.80

1.00

1.20

0% 20% 40% 60% 80% 100%

Speed, %

PU

Ou

tpu

t o

r P

U P

F o

r P

U E

ffic

Load HP Output

Efficiency, includingauxil

True Power Factor[kw/kva]

Dura-Bilt5 MV Efficiency Testing Typical Results

25 50 75 100

25 89.5 94 96 97

50 93.5 95 96.5 97

75 94 95.5 96 97

100 93 94.5 96 96.5

DATA ABOVE TAKEN FROM 800 KVA FRAME TESTING, May 2002,

ON DYNO LOAD - TYPICAL, NOT GUARANTEED

PERCENT of top SPEED

PE

RC

EN

T O

F

FU

LL

LO

AD

Efficiencies in

Italic, expressed

in %




In VFD Application

Weve defined the process loads and available

power, now whats the best solution?????

#2 - Define the

power system

and requirements

#1 - Define the

process loads

and duty cycle

#3

Determine best

drive solution!




In VFD Application

MV vs LV AC Drives: Cost Factors of Various Configurations

MV drive $ / HP decreases with HP

Harmonic content can be important:

MV data is 24 pulse TMGE DB5i MV

LV data is GE-Fuji AF300 P11

Installed cost must be considered

MV vs LV AC Drives

Budgetary $ per HP

vs HP

0.0

110.0

220.0

330.0

440.0

500.0

0 500 1000 1500

Horsepower

Bu

dg

eta

ry

$ p

er

Ho

rsep

ow

er

LV 6-Pulse w/o Transformer

MV 4160 v 24-Pulse DB5i

LV 6-Pulse w/8% Mirus filt

LV 18 pulse incl transf




In VFD Application

Drive Design For Reliability

Minimum parts fewest power components, and simplest firing circuits

No Weak links like marginally rated electrolytic caps

Conservatively rated, fully qualified components

Quality built in not burn-in tested

Quality tracked




In VFD Application

Drive Output Voltage & Motor Application

Why Pick LV [250 HP

Many users select MV over 500 HP.




In VFD Application

Some MV vs. LV Conclusions

For drives > 1000 HP, MV makes sense

For long cable runs, MV makes sense

For drives < 500 HP, LV makes sense.

If low power system harmonics are required, LV filter or multi-pulse

cost adders can favor MV over LV.

In the range 500 to 1000 HP the various application & installation

factors apply.

Final choice may boil down to user preference.




In VFD Application

Weve selected how to power our process, now lets control it and

keep it running!!!!!!!




In VFD Application

Speed & Torque Control Requirements

Each application is unique Simple, free-standing pumps

Complex e.g. sync to utility, multiple motors per drive, multiple drives on same load

Process control usually 4-20 Ma for speed

Go Tachless if possible Precise speed control rare with MV

drives and high KW level drives

High load torques [>150%] may require tach




In VFD Application

Operator Control and Communication

Interface with larger process controls for operator

Simple start-stop contacts

More complex HMI

Process equipment controls system PLC

LAN communication of drive status if/as needed to plant PLC or DCS

Plan for remote diagnostics capability




In VFD Application

Integrated Trend Window

Drag and drop variables

Real time trending or

archiving to buffer for

historical trending

Auto scaling

Zoom in/out function

Different views by using

variable hide feature

Analyze specific time with

cross hair

Frequency-based analysis of

trend with fast Fourier

transform function

Easy to Understand Data Structure: Drive parameters

and variables in tree

structure

Animated Block Diagrams

Drive Toolbox Interface

Important for Drive Success




In VFD Application




In VFD Application

Successful Drive Application: Electrical Factors & How They Relate to Success




In VFD Application

Design and Installation Factors Relating to Successful Application

Physical Environment of drive

Drive Design and Reliability

Motor Installation & Connections

Speed & Torque Control Requirements

Operator Control and Communication

Design for Maintainability and Installation




In VFD Application

Environment MV Equipment

Equipment is designed to be installed in a

relatively clean, dry environment

Operation

0 to 40 or 50 C with a relative humidity of 95%

maximum, non-condensing.

Storage

Equipment is generally designed for a non-operating

(storage) temperature range

of 25 C to 70 C.




In VFD Application

Environment at Location

Altitude: De-rate current rating 3% per 1000 ft above 3000 feet. May have to de-rate voltage for very high altitudes.

Temperature Derate (air cooled drive): 1.5% per degree C above base rating [usually 40C] up to max [usually 50 C].

Drives put out heat must be removed or vented to outside.

High-power drives are usually liquid cooled with remote heat exchangers.

In the presence of corrosives or dust or water - pick appropriate enclosure. [be careful of cooling!].




In VFD Application

Facility Readiness

Foundation Plans

Pads for transformers and switchgear

Pads or columns for Equipment houses

Off loading equipment

Cranes, fork-trucks

Personnel protection

Fences, signs, railings

Training




In VFD Application

Foundation Planning




In VFD Application

You can never have too big of a crane.says

the crane salesman !!!




In VFD Application

Site Planning




In VFD Application

Equipment House Issues

Placing Drives in Houses Dont Forget :

Drives sometimes come in many parts

some assembly required wiring, plumbing, etc.

Auxiliary power and cooling must be wired

How can drive be handled? Roll, fork, etc.

Placement must allow access and meet codes

Door swing, voltage clearance, cable termination, removable panels

Equipment heat dissipation (sensible heat) plus humidity

removal (latent heat) must be considered

May require redundancy in cooling system to give best up-time

on system




In VFD Application

Cables From VFD to Motors

Drives themselves are usually tolerant of most cable types & methods

BUT, Cabling affects EMI radiation or motor.

Cables > 500 meters need special attention [cable capacitance]




In VFD Application

Most Ideal Cable for PWM Inverter Use

Most critical for LV drives, much less critical for MV Drives

Continuous, Corrugated, welded aluminum armor, with 3 symmetrical ground conductors.

Minimizes EMI / Radiated noise

Minimizes common mode volts at bearings

Example PWM cable manufacturers:

LV - Annixter/BICC Philsheath

LV- Rockbestos Supernant Gardex CC

MV Okonite C-L-X Type MV-90 or MV-105

MV Amercable MM-VFD More flexible Bronze armor shield

First Choice 3 Phase Conductors 3 Symmetrical Grounds 1 Overall Shield/Armor




In VFD Application

Example Okonite

C-L-X MV-105

[8-15 kv]

3 Symmetric

Grounds

Continuous




In VFD Application

Example

Amercable MMV-

VFD [8-15 kv]




In VFD Application

Example General

Cable MV-Rig

[8-15 kv]




In VFD Application

PWM Motor Cabling 3-ground example

Minimizes injected ground current into Pcom bus for electronics reliability.

Reduces bearing currents from common mode currents.

Minimizes cross talk induced voltages on adjacent cables for noise immunity and safety sake.

Inverter to Motor cabling example: 3 grounds and continuous armor shield

P c o m m

C O N T R O L C I R C U I T S

P c o m m

S H I E L D

N E C

G R O U N D S

I N D U C T I O N

M O T O R

N E C F R A M E C O N N E C T I O N

P c o m m C o n n e c t i o n

C o n d u i t

B o x

E n c l o s u r e E x i t p l a t e

ARMOR




In VFD Application

PWM Motor Cabling 1-ground conductor example

Minimizes injected ground current into Pcom bus for electronics reliability.

Minimizes cross talk induced voltages on adjacent cables for noise immunity and safety sake.

Inverter to Motor cabling example: 1 ground and continuous armor shield

P c o m m

C O N T R O L C I R C U I T S

P c o m m

S H I E L D

N E C

G R O U N D

I N D U C T I O N

M O T O R

N E C F R A M E C O N N E C T I O N

P c o m m C o n n e c t i o n

C o n d u i t

B o x

E n c l o s u r e E x i t p l a t e

ARMOR




In VFD Application

Motor-Drive Cable Methods And Tradeoffs




In VFD Application

Drive Cabling Summary

For LV Drives, use triple-ground cable with overall extruded continuous armor, grounded as shown.

For MV NPC drives, use either single or triple-ground cable, with overall extruded continuous armor cable, grounded as shown.

Other cables may not cause trouble, but some risk is involved.

New NEC 2005 requires shielded cables!




In VFD Application




In VFD Application

Successful Drive Application: Design & Installation Factors & Relation to Success




In VFD Application

Drive Applications




In VFD Application

Thanks!

how to be successful in drive application · · 2015-12-03how to be successful in drive...

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