NPS
NPS
(OP)
Negative Phase Sequence anybody? To include Negative Phase Sequence Trip Imminent alarm and philosophy. And if we get any ops engineers interested, preferable reactions to the above.
Usual rules apply, preferably in words of one sylable or less.
Have fun
Usual rules apply, preferably in words of one sylable or less.
Have fun






RE: NPS
RE: NPS
Rafiq Bulsara
http://www.srengineersct.com
RE: NPS
RE: NPS
NPS is standard and very importnat function for generators and motors. ( for other objects can be used too).
Usually for generators used two stages, 1 for alarm and second for trip. Often used IDMT curve for trip.
Setting depend on requerements of generator vendor.
NPS is overheating of rotor, vibration.
It's very shortly.
Best Regards.
Slava
RE: NPS
An NPS relay normally has an IDMT curve as noted by Slava, and it should result in a unit trip, not an alarm. Rotor overheating is a very serious problem and it should not be left to an operator's opinion whether to trip the unit. An alarm which activates above a threshold is a worthwhile addition to give warning of an impending trip and allow the unit operator to inform the transmission system operator of a problem on the system. There is usually very little the operator of a generating unit can do to influence a negative sequence problem because it is almost always caused by a load imbalance out on the system.
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If we learn from our mistakes I'm getting a great education!
RE: NPS
Ooops sorry, started going off on one there, where were we? Oh yes............
I was actualy just recalling an alarm on an old AEI Machine that declared "NPS Trip Imminent". Fortunately I was never subjected to it in anger.
Was also wondering what sort of fault or incident causes Negative sequence in the first place.
RE: NPS
Bill
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"Why not the best?"
Jimmy Carter