Dual Unit Back To Back Test - Internal Faults - ABB REL 356 Instruction Booklet

External Fault(s) - Current connections
Unit #1
IA
IAR
IB
IBR
IC
ICR
3 ∅ Current Test Set
IA
IB
IC
STEP 2
Apply fault currents greater than those shown in Tables 5-1, 5-2 & 5-3 and verify that the relay does not trip on external
faults.

Dual Unit Back to Back Test - Internal Faults

To simulate an internal fault, reverse the CT polarity on unit number 2. Test the relay per Tables 5-1, 5-2 & 5-3 by
applying faults and verifying that the relay trips.
Internal Fault(s) - Current connections
IA
IAR
IB
IBR
IC
ICR
Æ
3
IA
IB
IC
Testing
REL356
TB6-6
TB6-5
TB6-8
TB6-7
TB6-10
TB6-9
TB6-6
TB6-5
TB6-8
TB6-7
TB6-10
TB6-9
Current Test Set
ABB REL 356 Current Differential Protection
Unit #2
TB6-6
TB6-5
TB6-8
TB6-7
TB6-10
TB6-9
IR
TB6-6
TB6-5
TB6-8
TB6-7
TB6-10
TB6-9
IR
REL356
IA
IAR
IB
IBR
IC
ICR
IA
IAR
IB
IBR
IC
ICR
5-9