Protective Function 32 for Power generator's application

[DanielElias]

Dear gentlemen:
I'd appreciate if Can anyone please tell me Since how many KVA OR MVA worth selecting in Protective relays the function 32 for Power Generator's applications

Thanks in advance

 

[dpc]

First, it is important to understand that the purpose of the reverse power relay is to protect the prime mover, not the generator. The generator is reasonably happy running as a motor within its capability curve.

Reverse power relays are often used even down to smaller reciprocating engines - 1000 kW and below.

They are more critical for steam turbines - to prevent overheating in the low pressure section and for hydro-generators to avoid cavitation damage.

Engine-generators can tolerate fairly high motoring - up to 25%, so the 32 function is fairly easy to implement.

For steam turbines it is more difficult because the relay must detect very low levels of reverse power using fully rated CTs.

 

[sykimk]

Please refer to IEEE STD C37.102 "IEEE Guide for AC Generator Protection", section 4.5.5.3.
But I think you need data of motoring power of prime mover and generator from manufacturers to determine the correct setting value. Please consult with the manufacturer.

 

[jbartos]

Suggestion: Reference:
IEEE Std 242-2001 Buff Book
4.4.4 Directional-power relay (Device 32)
4.4.4.1 Application
As the name implies, a directional-power relay functions when the real power component (watts) ?ow in a circuit exceeds a preset level in a speci?ed direction. Typical uses for this relay function include
a) Source power ?ow control. On systems having in-plant generation operating in parallel with the utility supply, a reverse-power relay sensing the incoming power from the
utility can be set to detect (and alarm or trip) when the generator begins to supply power to the utility company. Plants designed to sell surplus power to the utility
would not use a reverse-power relay for this purpose, unless it was blocked by an under-frequency relay.
b) Antimotoring of generators. This relay is used to detect the motoring power into a generator that has not been disconnected from the system following a shutdown of its
driver. See Chapter 11 for further information.