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Protections included in VSD

Protections included in VSD

Protections included in VSD


I'm designing an electrical facility to feed some motors (>75 kW) through VSD. We consider some ANSI proteccion functions in the switchgear (50, 51, 86) as if it was a feeder possition and we consider the specific motor protection functions in the engineered VSD. Some of the vendors in the bidding process claim that functions 48 (Incomplete Sequence Relay / Blocked Rotor) and 66 (Notching or Jogging Device/Maximum Starting Rate/Starts Per Hour/Time Between Starts) are not applicable in this case and therefore they don't include them. Those two functions are required by project specifications and I think they do apply.

Anyone with previos experience in this topic?

RE: Protections included in VSD

Quote (OP)

Some of the vendors in the bidding process claim that functions ......
If they are not the low bidder it doesn't matter.
If they are the low bidder, add the cost of engineering, supplying and installing those functions in a dedicated relay to their bid price.
Or point out that without those functions, their bid can not be accepted per the project specifications.
"Notching or Jogging Device/Maximum Starting Rate/Starts Per Hour/Time Between Starts" does not have the same importance with a VFD as with DOL starting, but it is usually easier to comply with the specs than it is to change the specs.

"Why not the best?"
Jimmy Carter

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