A070972 V3 EN
Figure 96: Incorrect connection of trip-circuit supervision
A connection of three protection IEDs with a double pole trip circuit is shown in the
following figure. Only the IED R3 has an internal TCS circuit. In order to test the
operation of the IED R2, but not to trip the circuit breaker, the upper trip contact of
the IED R2 is disconnected, as shown in the figure, while the lower contact is still
connected. When the IED R2 operates, the coil current starts to flow through the
internal resistor of the IED R3 and the resistor burns immediately. As proven with
the previous examples, both trip contacts must operate together. Attention should also
be paid for correct usage of the trip-circuit supervision while, for example, testing
the IED.
1MRS756378 D Section 7
Supervision functions
REF615 193
Application Manual
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