Danfoss VLT 380-500 V Design Manual page 127

Braking Design Guide
13.2.2 Control with Brake Function
The brake is protected against short-circuiting of the brake resistor, and the brake transistor is monitored to ensure that
short-circuiting of the transistor is detected. A relay/digital output can be used to protect the brake resistor against
overloading by generating a fault in the frequency converter.
In addition, the brake makes it possible to read out the momentary power and the mean power for the latest 120 s. The
brake can also monitor the power energizing and make sure that it does not exceed the programmable limit set in the LCP.
NOTICE
Monitoring the brake power is not a safety function; a thermal switch is required for that purpose. The brake resistor
circuit is not ground leakage protected.
Overvoltage control (OVC) can be selected as an alternative brake function. This function is active for all units and ensures
that if the DC-link voltage increases, the output frequency also increases to limit the voltage from the DC link, thereby
avoiding a trip.
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