Feeder Protection
Feeder Protection
Feeder Protection
FEEDER PROTECTION
Electrical feeders
- Basically Conductors
- Both insulated & non insulated
- May have joints
- Short / Medium / Long Feeders
- Long cables may store energy
- Current / Voltage feeders
FEEDER PROTECTION
Typical faults in Electrical feeders
EARTH FAULT….?
OVER LOAD
LOCKED ROTOR
SHORT CIRCUIT
WHAT IS A FEEDER PROTECTION
RELAY…
PROTECTION AGAINST
OVER CURRENT AND
EARTH FAULTS
CT RATING
-Transformer
-Feeder
CONVENTIONAL - 2O/C+1E/F
CONNECTIONS
R Y B OVER CURRENT RELAY
O/C
RELAYS
FEEDER PROTECTION
Over Current /E/F Relay
CONNECTIONS
R Y B E/F RELAY- RESIDUAL
O/C
RELAY
FEEDER PROTECTION
Over Current /E/F Relay
CONNECTIONS
R Y B E/F RELAY - WITH CBCT
O/C
RELAY
Over Current /E/F Relay FEEDER PROTECTION
CONNECTIONS
R Y B 2 PH. OVER CURRENT +
EARTH FAULT RELAY
3 x O/C RELAYS
FEEDER PROTECTION
Over Current /E/F Relay
CONNECTIONS
R Y B 3 PH. OVER CURRENT +
EARTH FAULT RELAY
4 x OC
RELAYS
FEEDER PROTECTION
CONCEPT OF
Definite Time
Trip Time delay
Inverse Time
CONCEPT OF :
INVERSE TIME CURVES
TMS SETTING
Over Current /E/F Relay FEEDER PROTECTION
I/Is 10
Over Current /E/F Relay FEEDER PROTECTION
t(I) = [ A ] * TMS
[ (I/Is)a – 1 ]
A a
TMS=1
Normal Inv 1.3 sec 4.39 2.18 1.68 1.44 1.3 1.1 .99
IMPORTANCE OF
MORE CURVES
Testing
SENSITIVE E/F
BREAKER FAILURE
FAULT LOCATION
UNBALANCE
AUTO RECLOSING
OVER CURRENT / EARTH FAULT RELAY
SENSITIVE E/F
- ISSUES
- SETTINNGS
OVER CURRENT / EARTH FAULT RELAY
CONVENTIONAL CDG61
VTT
NUMERICAL BUILT IN
SECOND HIGH SET
OVER CURRENT / EARTH FAULT RELAY
UNBALANCE
-VECTORIAL
- SCALAR
OVER CURRENT / EARTH FAULT RELAY
FAULT LOCATION
- V/I PRINCIPLE
OVER CURRENT / EARTH FAULT RELAY
- RECLOSE CONTACT
- RECLOSE TIME INTERVAL
- LOCK OUT
SCHEME COMPLICATIONS
- RECLOSE ON HS