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Asitha
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Join Date: Dec 2006
Posts: 88

Insulation testing of a 6.6 kV Generator

08/26/2008 10:53 PM

Dear Sir,

We have a 6.6 kV Synchronise generator (1500 kVA) in our mini hydro power plant. Here I want to test its insulation, what could be the method I can follow for this?

Including testing Voltage should be used for insulation testing to evaluate the insulation level of the generator.
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PWSlack
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#1

Re: Insulation testing of a 6.6 kV Generator

08/27/2008 3:24 AM

Follow the original equipment manufacturer's maintenance instructions, which will be found in their User Manual.

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dadw5boys
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#2

Re: Insulation testing of a 6.6 kV Generator

08/28/2008 12:00 AM

Like he said follow the instructions then test it at the systems breaker box or load dump.

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Anonymous Poster
#3

Re: Insulation testing of a 6.6 kV Generator

08/28/2008 8:59 AM

You mean 6.6 kW? If so, and you have 1500 kVA, the you are producing 230 Volts with the generator. The max leak-current is then calculated 230*1000 = 0,23MOhm.

You need to shut down the system, disconnect the generator and measure the insulation with an insulation meter (Megger), addjust the megger to 500V and test the phases to ground.

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Mundi
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wangito
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#4
In reply to #3

Re: Insulation testing of a 6.6 kV Generator

08/28/2008 9:09 AM

WHAT???

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sivaa
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Join Date: Aug 2008
Posts: 82
#5
In reply to #3

Re: Insulation testing of a 6.6 kV Generator

08/28/2008 10:45 AM

Hello Sir ,

Selecting the megger voltage range is based on which parameter ? , Please .
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ekiechle
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Join Date: Mar 2008
Location: South Texas - SOMETIMES
Posts: 88
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#6

Re: Insulation testing of a 6.6 kV Generator

08/28/2008 2:00 PM

Below is a chart with test voltage levels for different system voltages. 2500VDC is standard for medium voltage generators. If the machine is a wye configuration you will need to lift the neutral from the ground bus or resistor.

Be extremely careful, as depending on your system configuration it is possible to have more than one generator sharing neutral connection..

Insulation Resistance Test Values
Electrical Apparatus and Systems

Nominal Rating
of Equipment in Volts

Minimum Test Voltage, DC

Recommended Minimum
Insulation Resistance in
Megohms

250 500 25
600 1,000 100
1,000 1,000 100
2,500 1,000 500
5,000 2,500 1,000
8,000 2,500 2,000
15,000 2,500 5,000
25,000 5,000 20,000
35,000 15,000 100,000
46,000 15,000 100,000
69,000 and above 15,000 100,000
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sivaa
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Join Date: Aug 2008
Posts: 82
#7
In reply to #6

Re: Insulation testing of a 6.6 kV Generator

08/29/2008 9:53 AM

Will this Equip. voltage rating is irrelevant with Applied freq.rate ?

For transformers : references , please . Thanking you , Sir .
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ekiechle
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Location: South Texas - SOMETIMES
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#8
In reply to #7

Re: Insulation testing of a 6.6 kV Generator

08/29/2008 10:17 AM

yes, these ranges will work for transformers as well..

Frequency of power system does not matter as you are using DC test voltage with megger.
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sivaa
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Join Date: Aug 2008
Posts: 82
#9
In reply to #8

Re: Insulation testing of a 6.6 kV Generator

08/29/2008 10:20 AM

Thanks for all your Assistances , Thanks .
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Users who posted comments:

Anonymous Poster (1); dadw5boys (1); ekiechle (2); PWSlack (1); sivaa (3); wangito (1)

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