overcurrent coordination
DESCRIPTION
Theory of protection coordination using overcurrent relaysTRANSCRIPT
EE 434 POWER SYSTEM PROTECTIONLECTURE 16: OVERCURRENT COORDINATION
Ernesto Vazquez‐Martinez, ECERF
OC radial system protection
∆Τ
d
d
T
I
∆Τ∆Τ
Minimum fault condition
Minimum generation for a minimum fault current (I = 0.866 I3, or I‐G).
Relay Fault
MIN
PICK‐UP Protectionzone
FAULTMAX
Example using One‐Liner
R2R1
10MVAp.f.0.95
167.3A
8MVAp.f.0.95
133.8A
j0.1j0.2j0.15
34.5kV
Fault conditions
Initial coordination
0.05s
0.04s
Final coordination 1
T 0.29s
Final coordination 2
T 0.42s
Minimum fault condition
Coordination criteria
Initial coordination
Final coordination
Sensibility for MFC
The loads are taken of service. Use the positive sequence currents.
Ks=(1859/240) / 4 = 1.93 > 1.5
EE 434 POWER SYSTEM PROTECTIONLECTURE 16: OVERCURRENT COORDINATION
Ernesto Vazquez‐Martinez, ECERF