Chapter 15 - Supervision
Trip Output Relay
Figure 179: TCS Scheme 2
When the breaker is closed, supervision current passes through opto input 1 and the trip coil. When the breaker is
open current flows through opto input 2 and the trip coil. No supervision of the trip path is provided whilst the
breaker is open. Any fault in the trip path will only be detected on CB closing, after a 400 ms delay.
Optional resistors R1 and R2 can be added to prevent tripping of the CB if either opto-input is shorted. The table
below shows the appropriate resistor value and voltage setting for this scheme.
Trip Circuit Voltage
This Scheme is not compatible with Trip Circuit voltages of less than 48 V.
PSL FOR TCS SCHEME 2
Opto Input 1
Opto Input 2
*NC stands for Normally Closed.
Figure 180: PSL for TCS Scheme 2
In TCS scheme 2, both opto-inputs must be low before a trip circuit fail alarm is given.
TRIP CIRCUIT SUPERVISION SCHEME 3
TCS Scheme 3 is designed to provide supervision of the trip coil with the breaker open or closed. It provides pre-
closing supervision of the trip path. Since only one opto-input is used, this scheme is not compatible with latched
trip contacts. If you require CB status monitoring, further opto-inputs must be used.
Opto Voltage Setting with R1 Fitted
Resistor R1 and R2 (ohms)
CB Aux 3ph(52 -A)
CB Aux 3ph(52 -B)