Trip Circuit Supervision 74Tc; Description - Siemens SIPROTEC 7SJ62 Manual

Functions
2.11 Monitoring Functions
2.11.2

Trip Circuit Supervision 74TC

Devices 7SJ62/64 are equipped with an integrated trip circuit supervision. Depending on the number of avail-
able binary inputs (not connected to a common potential), supervision with one or two binary inputs can be se-
lected. If the allocation of the required binary inputs does not match the selected supervision type, then a
message to this effect is generated („74TC ProgFail").
Applications
• When using two binary inputs, malfunctions in the trip circuit can be detected under all circuit breaker con-
ditions.
• When only one binary input is used, malfunctions in the circuit breaker itself cannot be detected.
Prerequisites
A requirement for the use of trip circuit supervision is that the control voltage for the circuit breaker is at least
twice the voltage drop across the binary input (V
Since at least 19 V are needed for the binary input, the supervision can only be used with a system control
voltage of over 38 V.

2.11.2.1 Description

Supervision with Two Binary Inputs
When using two binary inputs, these are connected according to Figure 2-71, parallel to the associated trip
contact on one side, and parallel to the circuit breaker auxiliary contacts on the other.
Figure 2-71
212
Principle of the trip circuit supervision with two binary inputs
> 2 · V ).
ct BImin
C53000-G1140-C207-2, Release date 01.2008
SIPROTEC, 7SJ62/64, Manual