IS STEP DOWN TRANSFORMER REALLY REQUIRED ON OUR SET-UP

When you say that you put one line to ground are you referring to one of the three phases of the 3 phase 440V generator output?

Hallow dear .

1-Some generators have options to get required voltage by changing power cables (consult a technically awared person who under stand the mater of winding)

2-Tro to control the voltage from AVR

Dear Friend,

By connecting a phase for a single phase source will create the following problem.

1) It is not safe to connect directly to earth.

2) Connecting a single phase load in a single phase will create unbalance in the DG set.

Better to provide a step down transformer 440 V/ 215 V, it will avoid unbalance in the system.

When you will see power connection commimg out from winding you can see jumpers at out side of generator (before out put breaker) if so an expert can change power connection from 400volt out put to 230 volt out put three phase (this set up is for 3 phase arrangement not for single phase.

if power connection set up is not arranged by company(manufacturer of generator) than you have to go to arrange a transformer.

All confusing..

Dear, Why are you worrying about all this. Dont You have an electrician who can understand all this logic. I am unable to undersand the logic behind the idea of using ground. First of all ground the neutral of ur genset. Then run your load up to ur genset capacity without any worry.3phase motors will use all three phase and single phase 200V can be obtained from any phase and neutral. You will only need to care of equally distributing the load.No need of transformer if you genset is not kept far away from ur utilities or in other words, u dont have much voltage drop.440 volts are rarely set as genset out put. they are actuaaly kept up415V and u can also control ur voltage up to +-10% with the help of voltage adjustment pot....

It can't be.

Getting the power from one out of the three-phases at 440v 3-phase system will give you 440 divide by 1.732 = 254Vac. The voltage difference is 254-220=34volts which is high enough to burn your motor windings if plugged in longer time.

Some manufacturers in compliance with NEC the voltage supply for motor shall be plus or minus 2.5%-3% of the nameplate rating, thus 220x0.025= 4.4volts

At +2.5%; 220V+4.4V = 224.4V @-2.5%; 220-4.4V = 215.16V, though this scenario will affect the ambient motor temp but will little bit hurt your motor windings compared to 234V applied.

Hence, other option is to use the auto-transformer at least 25kva capacity to carry your 25hp, thus 25hp divided by 1.34kw/hp = 18.65 kw x 1.25 = 23.3 or say next higher rating is 25kva.

Your auto transformer will be 25kva @440/380/220 volts 3-phase

Please mention the type of winding of your generator. (star or delta). Also, if neutral is not available, a transformer is compulsory. If neutral is available , it is to be used for single phase loads, but not the ground wire.