What is Fail safe feature?

• AC Drives do not offer protection for brake resistor failures. DBR fail safe feature will only protect VFD against resistive element turn to turn short or element to ground shot. (Resistive element experience in expansion when subjected to repeated heating and cooling which normally happens while DBR working)
• If element turn to turn short will lead to resistor value reduce to below recommended minimum value resulting chopper module failure in VFD.
• Similarly if element short to ground will lead to VFD DC Bus short, resulting whole VFD rectifier section failure.
• Their unique construction adapted to resistive element encapsulation, arrest turn to turn short and also element short to ground.
• This fail safe feature is only available with GR DBR. This feature is essentially required for the braking resistors use in VFD applications.

 Braking resistor – Short time Pulse Rating:

• The VFD manufacturers recommend that the minimum requirement for braking resistor is to meet short time pulse rating of 10 times of continuous power for 12 sec. This means that the1KW capacity resistor to with stand short pulse rating of 10KW power for 12 sec. the unique design of encapsulated constructions allow our resistor to meet this short time pulse rating.
• The best designed conventional wire wound resistor has a short time pulse rating is only 10 times power for 5 sec. To meet 10 times power for 12 sec, the conventional resistor capacity is to be over sized to 2.4 times.