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page
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Join Date: Jan 2012
Posts: 25

Testing a New Generator

08/08/2012 2:52 AM

Hi all!

I am on verge of buying some new generators, therefore I would like to know what kind of test you can do on new generator before buying them? Actually a month ago I was at this generator dealer and there a test being performed on one of other client generator. They connected the three phases of the generator inside a 200 liters plastic drum filled with a liquid( they told later that it was water and mix wit salt). Actually for some reason, I had to leave before I could witness the test. When I came back the test was done. There was smoke coming out of the drum. Then I started asking questions regarding the test. They said they did switch the main breaker and let the generator run for a couple of minutes. Then I ask if the breaker did not trip. They said it did not trip because the neutral was not inside the drum. I think it was a 250KVA , 400 volts, 50 hz generator, Perkins. Anybody knows what kind test is that? and what do you gain by doing such a test? regards, Page
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PWSlack
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#1

Re: Testing a new generator

08/08/2012 3:21 AM

Do some more research before buying anything.

Consider hiring instead.

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Joshi
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#2

Re: Testing a new generator

08/08/2012 6:36 AM

That was an improper load test of the generator.
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PeterT
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#3

Re: Testing a New Generator

08/08/2012 8:27 AM

What you saw was a field load test, with an improvised "water resistor." I have seenthe same done with a generator system (I think they were around 1500kW each), using a metal trash dumpster filled with standard tap water. There is enough impurity in the water for it to conduct just fine.

The installing contractor made up a triangular jig with 3 electrodes (one for each of the 3 phases) that was connected to the generator output. The ends of the electrodes were dipped down into the water by a forklift. Since the neutral wasn't connected, there was no current there - it all flowed between the phases (after an insulation resistance test had been done to verify no leakage to ground from each phase!).

There was quite a light show in the tank as we looked down into it. You could see the arcs of the current between the 3 electrodes, but the resistance of the water was enough to keep it within normal current ranges.

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#6
In reply to #3

Re: Testing a New Generator

08/09/2012 2:55 AM

Thanks Peter T.

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lyn
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#4

Re: Testing a New Generator

08/08/2012 10:34 AM

You should commission someone as your agent and have them perform a technical evaluation of candidate generators. They will know what tests, if any, can be run on the generators.

A little knowledge is a dangerous thing. You have a little knowledge.

Seek help from someone other than an anonymous forum.
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KJK/USA
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#5

Re: Testing a New Generator

08/08/2012 11:45 AM

Factory testing and certification always takes place either with or without the buyer present.

Have you asked the dealer about on-site start-up, testing and commissioning?

A salt water load bank test for a couple minutes Surely you jest????

Are industrial resistive load banks available in your area?

What brand generator is it that you are considering?

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page
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#9
In reply to #5

Re: Testing a New Generator

08/09/2012 12:57 PM

Yes I did ask for start up and testing. Commissioning?!I will install and do the commissioning. Actually most dealers do not have industrial resistive load banks in my area. It is one with a Perkins´s Engine and Sommers generator.

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corbinstein
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#7

Re: Testing a New Generator

08/09/2012 7:59 AM

GA to KJK..... Load Banks are the way to go...

That way one can be sure of the load that's applied and if done properly, load banking is relatively safe.

Load banking can also help you find a weakness in the generating system as well as to engine, etc, driving the generator/Alternator unit.
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KJK/USA
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#8
In reply to #7

Re: Testing a New Generator

08/09/2012 8:29 AM

Thank you sir!

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Users who posted comments:

corbinstein (1); Joshi (1); KJK/USA (2); lyn (1); page (2); PeterT (1); PWSlack (1)

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