PROTECTION RELAYS FOR ALTERNATOR OF 2000kVA RATING

[navin34]

HI,

Could anybody tell me what protections (Relays: function/type) to be considered for 2000kVA 415v, Solidly earthed generator coupled with diesel engine. Also tell what protections (alrm/trip)are required for engine for safe operation of DG set.

Please also inform articles related to generator protection available on net.

 

[sykimk]

Please refer to IEEE STD C37.102 "IEEE Guide for AC Generator Protection"
In addition, please visit the following web

http://www.beckwithelectric.com/infoctr/protect.htm

The referred site contains quite useful documents.

 

[dpc]

This will depend somewhat on the application - protection rfequirements for standby generator will be different than a unit to be base loaded and connected to the grid. Interconnection details will also impact the protection.

In general:

Gen differential
Voltage-controlled overcurrent
Under/overfrequency
Under/overvoltage
ground/neutral overcurrent
Negative sequence current overcurrent
Winding temperature (stator rtds)
bearing overtemperature

synch-check relay if synchronzing is required
Loss-of-field

You can get all this is in a single relay - GE/Multilin SR-489 or similar by Schweitzer and others.

 

[ScottyUK]

Suggest Alstom's P432 and P343 are worth a look. They incorporate a very similar set of functions to the SR-489.

A general note to anyone looking for Alstom's relay business: it has been sold to Areva.

http://www.areva-td.com

 

[Arevaengineer]

In addition to dpc's reply.
Reverse power
Diode Monitor
are also essential especially with a diesel engine as prime mover, a sudden loss of fuel supply will cause the generator to regenerative motoring or in other words reverse powerBut again it depends on the application, whether island or connected to the grid.
For the diesel engine.
Lube oil pressure alarm/trip
HT cooling water temp.alarm/trip
LT cooling water alarm/trip.
Fuel pressure alarm/trip.
Exhaust temp.alarm/trip.
HT cooling water level alarm
LT cooling water level alarm
Oil mist detection alarm/trip
Main bearing temp.alarm/trip
Overspeed trip.

I hope this was some help to you.Alstom's P343 relay as ScottyUK suggested is an ideal choice for generator protection.

General noteScottyUK)Not only the relay business but the whole transmission and distribution business has been sold to Areva.

 

[sgelec]

reverse power relay is also incorporate if synchronising with grid. rest mentioned will be sufficient.
thanks

 

[jbartos]

Suggestion: It is not clear in the original posting whether or not the generator is an emergency generator.
In USA, such generators must comply with NFPA 70, NFPA 110, and NFPA 99 (life safety).
For the generator protection visit:

http://www.basler.com

http://www.ge.com

etc.

 

[alehman]

Many protection functions are integral to some standard packaged generator sets. You may want to check what is provided with the unit.

As mentioned by dpc, the functions that are desirable depend on the application. Isolated standby units typically have much simpler protective relaying. If continuity of service is more important than protecting the generator, such as for life safety applications, less protection is sometimes desirable. Differential protection is unusual on low voltage generators unless it is interconnected with utility. You would normally want ground overcurrent as either an alarm or trip function. Loss of field can have nuisance trips if supplying capacitive load (e.g. UPS).

 

[ScottyUK]

Just spotted my dyslexic fingers at work again:

I should have typed [blue]"...Alstom's P342 and P343 are worth a look..."[/blue]. I don't know if a type P432 relay even exists - apologies for the error.

 

[riteshbharat]

Answer to ScottyUK - Yes MiCOM P432 does exist and its a Fast Distance Protection and Bay Control Unit and it comes from Alstom's (now Areva) German unit (erstwhile AEG).

I also feel MiCOM P343 would be an ideal choice for 2MVA genset.

Cheers

 

[jbartos]

Suggestion: Low resistance or reactance system grounding is recommended. The protective relay ANSI Device Numbers are 32, 40, 46, 51GN, 51V, 59*, 87G
* is required for hydrogenerator which is to be assessed for the Diesel prime mover.