M3 Breaker Maintenance; W1 (W2) Breaker Trip Coil - GE SR345 Instruction Manual

CHAPTER 7: MAINTENANCE

M3 Breaker maintenance

W1 (W2) Breaker trip coil

Output Relay 1 (TRIP)
897786.cdr
345 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
Courtesy of NationalSwitchgear.com
The Trip coil monitoring is performed by a built-in voltage monitor on the Form A output
relays: RLY1 W1 BKR TRIP and RLY2 W2 BKR TRIP. The voltage monitor is connected across
the Form A contact, and effectively the relay detects healthy current through the circuit.
An external jumper must be made between terminals "A2" and "A3" for Output Relay 1
(RLY1 W1 BKR TRIP) coil monitoring and "B$" and "B5" for Output Relay 2 (RLY2 W2 BKR TRIP)
coil monitoring.
As long as the current through the Voltage Monitor is above the threshold of the trickle
currents (see Technical Specification for Form A output relays), the circuit integrity for the
Trip coil is effectively normal. If the Trip coil circuit gets disconnected, or if in general a high
resistance is detected in the circuitry, a Trip alarm will be set and the "ALARM" and
"MAINTENANCE" LEDs will be on.
Example 1: The figure below shows the connections of the breaker trip coil to the relay's
trip output relay for voltage monitoring of the trip circuit.
Figure 2: Trip Coil circuit with voltage monitoring
DC +
External
jumper
A2
B3
V
A3
52a
contact
Trip
Coil
DC -
Example 2: Some applications require that the Trip coil be monitored continuously,
regardless of the breaker position (open or closed). This can be achieved by connecting a
suitable resistor (see the table) across breaker auxiliary contact 52a in the trip circuit. With
such connections, the trickle current will be maintained by the resistor when the breaker is
open. For these applications the setting for "BYPASS BKR STATUS" should be set to
ENABLED.
M3 BREAKER MAINTENANCE
Output Relay 2 (TRIP)
B4
A4
V
B5
contact
DC +
External
jumper
52a
Trip
Coil
DC -
7–5