Single Unit Loopback Test - External Faults; Dual Unit Back To Back Test - External Faults - ABB REL 356 Instruction Booklet

ABB REL 356 Current Differential Protection

Single Unit Loopback Test - External Faults

No external fault testing is possible with a single unit since there is no way to invert the signal coming into the
receiver to simulate an external fault or load current.

Dual Unit Back to Back Test - External Faults

STEP 1
To test the relays back to back several connections need to be made that are dependent on the communication channel
used. Make the connections shown for your option.
9600 Audio Tone Option
X M I T O U T T B 4 - 1 1
X M I T O U T T B 4 - 1 2
R C V R I N T B 4 - 1 3
R C V R I N T B 4 - 1 4
56/64 kbps Direct Digital Option
The Direct Digital option requires a DB-25 to DB-25 cable hooked between Unit #1's DCI assembly and Unit #2's DCI.
Connectors on the DCI are male gender so the cable needs to be female gender on both ends. Connections are as
follows:
Pin 2 tp pin 3 (TXA to RXA)
Pin 14 to pin 16 (TXB to RXB)
56/64 kbps Fiber Optic Option
The Fiber optic option requires a fiber optic cable with an in-line attenuator be placed between the XMIT connector of Unit
#1's DCI to the RCVR connector of Unit #2's DCI. The same connection needs to be made from Unit #2 to Unit #1. Set
the in-line attenuators for a received level of -26dbm.
With any one fo the three communciations options chosen a few settings need to be changed before back to back
testing can be performed.
Both Units
LPBK = NO
ALDT = YES
5-8
T B 4 - 1 3 R C V R
T B 4 - 1 4
T B 4 - 1 1
T B 4 - 1 2 X M I T O U T
Pin 3 to pin 2 (RXA to TXA)
Pin 16 to pin 14 (RXB to TXB)
Unit #1 Unit #2
UNID = 0 UNID = 1
I N
R C V R I N
X M I T O U T
Testing