coordination of non-directional overcurrent relays for 132 kv substations

1. Coordination of
non-directional Overcurrent Relays

2. Agenda
• Coordination for non-directional overcurrent
protection relays for 132 KV substations

3. This substation
consists of
1- Step-down power transformers
132/33 KV, 63 MVA.
2- Switchgear 33KV each one
contains on four feeders, as well
as bus section 33KV.
3- High voltage circuit breakers
132KV.
4- Medium voltage circuit breaker
33 KV.
4- Current transformers.
5- overcurrent relay.

5. Calculation of time for feeders 33 KV
T , I set = 1.2 rated current
No of
relays
Positions CT ratio
Forward
Short circuit
current(A)
Reverse
Short
circuit
current (A)
Rated
current
(A)
Pickup
Primary
Current
(A)
Pickup
secondary
Current
(A)
T.M.S
Time
(sec)
Relay 5 Feeder 1 300/5 26302 1001 175 210 3.5 0.05 0.221
Relay 6 Feeder 2 300/5 26102 1201 210 252 4.2 0.05 0.221
Relay 7 Feeder 3 300/5 26002 1301 227.4 273 4.55 0.05 0.221
Relay 8 Feeder 4 300/5 25802 1501 262.43 300 5 0.05 0.214
Relay 10 Feeder 5 300/5 26302 1001 175 210 3.5 0.05 0.221
Relay 11 Feeder 6 300/5 25802 1501 262.43 300 5 0.05 0.214
Relay 12 Feeder 7 300/5 26202 1101 192.45 231 3.85 0.05 0.221
Relay 13 Feeder 8 300/5 25702 1601 179.93 300 5 0.05 0.206

6. Calculation of TMS for incomer, Bus section 33 KV and
main overcurrent 132 KV. T
No of
relays
Positions
CT
ratio
Forward
Short
circuit
current(A)
Reverse
Short
circuit
current (A)
Rated
current
(A)
Pickup
Primary
Current
(A)
Pickup
secondary
Current
(A)
Coordination
Time interval
Time
(sec)
TMS
Relay 9
Bus
section
1200/5 13551 13751 1200 1200 5 -0.06 0.2 0.071
Relay 3
Incomer
1 33 KV
1500/5 9232 5204 1102.1 1200 4 0.3 0.506 0.107
Relay 4
Incomer
2 33 KV
1500/5 9232 5204 1102.1 1200 4 0.3 0.506 0.107
Relay 1
TR1
132KV
300/5 2038 30855 275.55 300 5 0.2 0.706 0.444
Relay 2
TR2
132KV
300/5 2038 30855 275.55 300 5 0.2 0.706 0.444

7. Thank you for watching