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Transformer vs Generator

Transformer vs Generator

Transformer vs Generator

(OP)
Hi all,

is it possible for a 275 kW generator to energize a 225 kVA transformer, and makes it work ?
the inrush of transformer is around 12x In, can the generator supply this current at starting ?

thank you

RE: Transformer vs Generator

The inrush will draw the terminal voltage down. As the terminal voltage drops the inrush current will drop. The voltage will drop to the point that the generator is able to supply the required current. The prime mover may also lose speed dropping the frequency. If/when the frequency drops more than 3 Hz the UFRO will become active and commend the voltage proportionally lower. Then as the inrush subsides the terminal voltage and frequency will recover to normal levels.
Ideally the transformer will be unloaded when it is energized.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Transformer vs Generator

Can you allow the transformer primary breaker to be closed while the set runs up to speed? If you can do that then the generator AVR will ramp up the terminal voltage and energise the transformer without any inrush.
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

RE: Transformer vs Generator

(OP)
The transformer is loaded at 60%, and the breaker protecting this transformer remains closed when the normal distribution is lost.
As far as i know, loads connected on a transformer have no effect on its inrush current, also when the normal distribution is lost, a signal is sent from the ATS to start the genset.
the genset has to reach it's normal operational conditions before the ATS switches to emergency power. Meanwhile the transformer had time to de-energize through ATS grounding.
When comes time the start the transformer, i can't figure out how the genset can supply enough current to energize the transformer windings.
 

RE: Transformer vs Generator

It can't. Read my first post. (It may trip the breaker)

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Transformer vs Generator

GE multilin transformer relays, UR T60 & T35, claim to prevent the breaker tripping during transformer energization.  

Muthu
www.edison.co.in

RE: Transformer vs Generator

That's probably a harmonic restraint function which uses the high third harmonic component during energisation to bias the tripping curve - a fairly common technique and dates back many years. Those are quite expensive relays to use to protect a little machine and a small transformer. wink
  

----------------------------------
  
If we learn from our mistakes I'm getting a great education!
 

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