Inverters of size 1 – 3

If an external bimetallic relay is used with the inverter, there are 3 possible connections:

Note that the reference potential GND of the digital inputs on the controller must be the same as the reference potential of the inverter when connection 1 is used.

• Connection 1
• The digital input of the inverter connected to the signal contact of the external bimetallic relay must be parameterized to the function "External braking resistor fault".
• If the thermal circuit breaker trips, the signal is evaluated in the inverter and the PLC.
• If the thermal circuit breaker trips, the PLC must interrupt the power supply.
• If the thermal circuit breaker trips, the inverter switches to "Output stage inhibit".
• Connection 2
• If the thermal circuit breaker trips, the signal is evaluated only in the PLC.
• If the thermal circuit breaker trips, the PLC must interrupt the power supply.
• If the thermal circuit breaker trips, there is no direct response in the inverter.
• With connection 2, it is possible that the PLC finishes the current travel cycle although the thermal circuit breaker has tripped. Only then is the power supply disconnected. In this case, the residual braking energy W_Rest = P_BRnom × 20 s must not be exceeded.
• Connection 3
• If the thermal circuit breaker trips, the signal directly affects the line contactor.
• A response by the PLC is not required.
• If the thermal circuit breaker trips, there is no direct response in the inverter.