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Join Date: Dec 2011
Posts: 35

3 Phase AC Generator Direction

02/01/2013 4:47 AM

hi gents,

will you please help me on this.

its an old 25 kva 3 phase ac generator 5o hz and i would like to fit it to an old engine.

as i can see before is that most generators are turning clockwise.

this engine is turning opposite direction from the normal engines direction.

what i am wondering is if i fit this generator to this engine and run it, will it generate power or it does not worth trying?

hope you got what i mean and will appreciate your help.

thanks

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#1

Re: 3 Phase AC Generator Direction

02/01/2013 9:25 AM

YES. It will generate power.

DHAYANANDHAN.S

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#2

Re: 3 Phase AC Generator Direction

02/01/2013 2:38 PM

Yes, it will generate power. Note that if it is a 3 phase unit and you connect generator terminals A-B-C to same letter motor terminals , the motor will turn backwards.

To get normal motor direction, you must connect as below (terminals may have A-B-C, R-S-T or 1-2-3 marking, it is the alphabet or number sequence that matters) :-

Generator ------- Motor

C (3) ----------- A (1)

B (2) ----------- B (2)

A (1) ----------- C (3)

67model

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#3

Re: 3 Phase AC Generator Direction

02/01/2013 11:05 PM

No problem with the direction. You only wire the 3 phases in reverse for the user's feed. IF the excitation is via sliprings and brushes - as some older ones do - check that the brushes make good contact. Check, that the bearings are well lubricated. Old lube might be dry, the seals may be worn. Pull maintenance on them.

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#4

Re: 3 Phase AC Generator Direction

02/02/2013 5:38 AM

Hello folks,

In case of doubt, connect the gen in front of your engine, instead of in the back and all senses of turning will be respected.

I hope!

BRZK

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#5
In reply to #4

Re: 3 Phase AC Generator Direction

02/02/2013 6:30 AM

Only thing i'd add is to check that the cooling fan on the alternator rotor is bi-directional otherwise you may derate the capacity of the alternator due to lack of cooling...

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#6

Re: 3 Phase AC Generator Direction

02/04/2013 12:20 AM

If it does have slip rings and brushes for field excitation, make sure that the brush holders are set properly for reverse rotation.

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#7

Re: 3 Phase AC Generator Direction

02/04/2013 6:25 AM

Pardon me if this was already obvious. If the generator marked direction is clockwise, looking onto the drive end - Then the engine to drive it has anti-clockwise rotation, looking onto its output shaft.

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