Question: When should I add a brake resistor to my drive?


When the speed reference of a frequency converter is reduced, the motor acts as a generator and brakes. When a motor acts as a generator, it supplies energy to the frequency converter which is collected in the intermediate circuit.

The function of the brake resistor is to provide a load on the intermediate circuit during braking, thereby ensuring that the braking power is absorbed by the brake resistor. If a brake resistor was not used, the intermediate circuit voltage of the frequency converter would continue to increase, until it cuts out for protection.

The advantage of using a brake resistor is it enables braking of a heavy load quickly, e.g. on a conveyor belt. Danfoss has chosen a solution in which the brake resistor does not form an integral part of the frequency converter.

This offers the user the following advantages:
- The resistor time cycle can be selected as required
- The heat developed during braking can be conveyed beyond the panel cabinet to allow the energy to be used
- There is no overheating of the electronic components, even if the brake resistor is overloaded

Manufacturer Part Number: 175U0903