Rockwell Automation 865 Differential Protection Relay - Manual (Page 158)

8-16 Applications
865-UM001A-EN-P – July 2009
Trip Circuit Supervision Trip circuit supervision is used to ensure that the wiring from the
protective relay to the circuit breaker is in order. This circuit is most
of the time unused, but when the protection relay detects a fault in
the network it is too late to notice that the circuit breaker cannot be
tripped because of a broken trip circuitry.
A digital input of the relay can be used for trip circuit monitoring.
The digital input is connected to an auxiliary miniature relay,
which is connected parallel with the trip contacts.
A resistor module enables supervision also when the circuit
breaker is open. The module consists of a resistor for 110 V dc
and is connected according the auxiliary voltage.
The digital input is configured as Normal Closed (NC).
The digital input delay is configured longer than maximum fault
time to inhibit any superfluous trip circuit fault alarm when the
trip contact is closed.
The trip relay should be configured as non-latched. Otherwise a
superfluous trip circuit fault alarm will follow after the trip
contact operates and remains closed because of latching.
CB
CLOSE COIL
OPEN COIL
close control
trip circuit
failure alarm
R1
-V
AUX
+V
AUX
-V
AUX
865
Digital input
Trip relay
Delay
Alarm relay
for trip
circuit failure
relay compartment
circuit breaker compartment
+
K1
1
DI
+48 V
A snap in relay module K1:
Phoenix Contact EMG 17-REL/KSR-120/21 Au
Coil: 96 .. 127 V, 24 kohm
Contact material: 5 mm Au (AgPd60)
Width: 17.5 mm
Assembly: DIN EN 50022 mounting rail
TripCircuitSup200CloseP os
Figure 8.10 – Typical Trip Circuit Supervision when Circuit-breaker is Closed
(Supervised circuitry in this CB position is double-lined. Digital input is in active state)