External thermal relay operation

What does OH Fault mean?

This fault indicates that an external thermal relay, typically used for motor overheat protection, or an internally mounted temperature relay in the motor, has operated (contacts opened), causing the inverter output to stop. The inverter requires a reset to restart after this fault. This function is active only when '7' (OH signal) is assigned to Pr. 183 'MRS terminal (MRS) function selection'.

• Motor overheating due to excessive load, insufficient cooling, or an extended operating duty cycle.
• Improper setting of Pr. 183 'MRS terminal (MRS) function selection' if an external thermal relay is not intended for use with the MRS terminal, or if it is set incorrectly.
• Malfunction of the external thermal relay or its connection to the MRS terminal.

Click steps to track your progress.

1. 1

   Reduce the motor load and/or operating duty cycle to prevent motor overheating.

2. 2

   Verify that Pr. 183 (MRS terminal function selection) is set to '7' if an external thermal relay is connected, or adjust it if the functionality is not desired.

3. 3

   Inspect the motor's cooling fan and ensure the motor's ventilation path is clear of obstructions.