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Join Date: Aug 2014
Posts: 1

Power Distribution

08/04/2014 2:12 AM

my factory is fed from 410kva generator. sometimes the neutral line carries current. and one of the 3-phase lines become neutral. voltage reading becomes like this VL-VL=400V, VL-VL=400V,VL-VL=230,VL-VN=400V. 2 days when like this happened i saw my projector lamps 400w were gone off and burned, when i disconnected these it became ok.what is the solution.

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#1

Re: Power distribution

08/04/2014 2:38 AM

The only one solution would be to have en electrician check for faults while in the intermediate time you should shut of the operation, which should getting an accredited electrician in much easier and faster.

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Join Date: Aug 2014
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#2

Re: Power distribution

08/04/2014 5:11 AM

First of all you have to disconnect your loads , then start your generator measure the output from the generator , make sure that any line to line voltage is 400 V , and any Line to neutral voltage is 230 V , then check the connections from the Generator local panel to the main distribution panel make sure that the line cable is not switched with neutral cables , check if there is any problems in the cables , check all your connections and cables step by step from your source to the loads , until you find the area causing such problem

* most important thing is to check your earthing network , if you have good earthing this shouldn't happen in normal cases .

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#3
In reply to #2

Re: Power distribution

08/04/2014 5:49 AM

I forget to tell you to make sure that the loads are approximately balanced on the the 3 phases this maybe a cause of your problem

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Guru
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#4

Re: Power distribution

08/04/2014 8:07 AM

One of the likely causes is a loose neutral connection. Have the installation shut down and get a qualified Electrican chase-out and remedy the fault.

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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#7
In reply to #4

Re: Power distribution

08/05/2014 2:53 AM

...before re-energising.

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#5

Re: Power Distribution

08/04/2014 2:09 PM

Some where in the load distribution, there is neutral cut.

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#6

Re: Power Distribution

08/05/2014 1:24 AM

Hi mate, was there any work done on your Generator....then may be they swopped the polarity on one of the phases....get someone to do the polarity on all phases of the Gen and connect it in the correct sequence....good luck

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Guru

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#8

Re: Power Distribution

08/05/2014 10:29 AM

If you are taking the measurements directly at the generator output terminals then you definitely have an issue with the "WYE" neutral connection at/in the generator.

If you are taking the readings downstream of the generator output terminals after the output circuit breaker the fault could be in the wiring between the generator output and the load device/equipment.

On some generators the output breaker is a four pole unit that switches the neutral as well as all three phases. If this is true in your case I would be suspect of a high resistance neutral contact in the breaker.

To identify the source of the fault take readings on the input wiring to the generator output breaker P-to-P and P-to-N then take readings at the load side terminals and compare the readings. If the readings on the input are ok and the readings on the load side of the breaker are not the same, the breaker is bad.

If the fault exists on both sides of the breaker terminals then the fault is in the generator windings or in the wiring between the generator windings and the breaker input.

Be careful and be sure to use a high impedance meter to take the readings as it is easy to inadvertently short or ground the wiring and suffer a dangerous fault.

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