JohdotaDevice guide Play
Device guide / Circuits
07

Fault indication

When the motor protection trips, the motor stops and the fault light comes on. The motor does not start by itself when the protection is reset.

LNQ11314S01112S11314K11314K1A1A2Q12122H1
The NO auxiliary contact 13–14 of motor protection circuit breaker Q1 is in series with the control circuit, and the NC contact 21–22 lights fault light H1.

How it works

LNQ1S0S1K1K1Q1H11Motor running

Q1 is on, so 13–14 is closed and 21–22 is open. K1 is latched.

LNQ1S0S1K1K1Q1H12Q1 trips

13–14 opens and K1 de-energises. 21–22 closes and fault light H1 comes on.

LNQ1S0S1K1K1Q1H13Start while tripped

Pressing S1 does not help, because the contact of Q1 is open.

LNQ1S0S1K1K1Q1H14Q1 reset

H1 goes off. K1 does not energise, because the self-holding was released. The motor is started again with S1.

Fault indication uses the auxiliary contacts of a motor protection circuit breaker. The NO contact stops the motor when the protection trips, and the NC contact lights the fault light.

Wiring

  • NO contact 13–14 is in series with the control circuit. When the protection trips, K1 de-energises and the self-holding is released.
  • NC contact 21–22 is wired to fault light H1.

The auxiliary contact follows the position of the breaker, so the fault light is also lit when the breaker is switched off by hand. If a trip has to be told apart from switching off by hand, a separate trip signalling contact is used.

With a thermal overload relay

When the motor circuit is built with a switch-fuse and a thermal overload relay, the same is done with the contacts of the overload relay: NC contact 95–96 in series with the control circuit and NO contact 97–98 to the fault light.

Sources

  1. ABB: MS116 and MS132 motor protection circuit breakers, catalogue
  2. ABB: TF65 and TF96 thermal overload relays, technical data