Neutral tripping characteristic when circulating current happen(genset parallel)

Hi,

When you are synchronising the Gensets the following Parameters are mandatory -

1 Equal Voiltage of the Alternators to be synchronised.

2. Equal Speed of the Engines

3. Same Phase Sequence - Direction of Phase Rotation

4. Same Phase / Load Angle of the Alternators - I Mean to Say the Potential Difference Between the Same Phase of Different Alternators.

If First two Cases are not matched exactly & balance two are ok , then you can synchronise the Genset but the Circulation current will flow between the Alternators because of the uneuqal Voltage & Frequency.

Point to be noted is although after synchronising the Alternators the Terminal Voltage on the Bus Bar is Same the Generated Voltage of the Alternators is same what has been set during the Initial Set Up.

The Amount of this Circulation current Depends upon the Voltage & Frequency Differences.

Circulating current = current circulating between the two generators and due to differences in the voltages of the same phases.

Since the Generators have been synchronised successfully at the start, the frequency and phase sequences should be correct and OK. The phase to phase voltage between identical phases should be ZERO ideally, but some difference can appear due to settings and/or fluctuations or differences in characteristics...hence a circulating current between the generators. This should be kept very low.

Neutral tripping: Due to the same as per above, and to some imbalnce in the load, there will be some neutral current flowing also. This is also controlled and should remain minimal.

Your statement of the problem is lacking vital information -

1. Have these generators ever been paralleled before ?

2. Have these generators ever run correctly in parallel before ?

3. Was cleaning, maintenance or other repair work performed immediately before this problem started ?

These answers can help prevent "tail chasing" and guessing.