Broken Conductor (46Bc); Trip Circuit Supervision (74Tcs); Figure 5.4-1 Logic Diagram: Broken Conductor Function (46Bc); Figure 5.5-1 Logic Diagram: Trip Circuit Supervision Feature (74Tcs) - Siemens 7SR224 Technical Manual

5.5

Broken Conductor (46BC)

The element calculates the ratio of NPS to PPS currents. Where the NPS:PPS current ratio is above 46BC
Setting an output is given after the 46BC Delay.
The Broken Conductor function can be inhibited from
Inhibit 46BC
Figure 5.5-1 Logic Diagram: Broken Conductor Function (46BC)
5.6

Trip Circuit Supervision (74TCS)

The relay provides three trip circuit supervision elements.
One or more binary inputs can be mapped to 74TCS-n. The inputs are connected into the trip circuit such that at
least one input is energised when the trip circuit wiring is intact. If all mapped inputs become de-energised, due to
a break in the trip circuit wiring or loss of supply an output is given.
The 74TCS-n Delay setting prevents failure being incorrectly indicated during circuit breaker operation. This delay
should be greater than the operating time of the circuit breaker.
The use of one or two binary inputs mapped to the same Trip Circuit Supervision element (e.g. 74TCS-n) allows
the user to realise several alternative monitoring schemes – see 'Applications Guide'.
Figure 5.6-1 Logic Diagram: Trip Circuit Supervision Feature (74TCS)
©2010 Siemens Protection Devices Limited
A binary or virtual input.
7SR224 Argus Description of Operation
Chapter 1 Page 60 of 70