Over voltage tripping

[Unique Stitch Binder]

Respected teachers of the field and colleagues
Assalam o Alaikum,

A DG of CUMMINS 250KVA (400volts) is running satisfactory at start almost an hour. Than gradually voltage increases on all three phases and trips at 413 voltage per phase.
What troubleshooting can be tried?

 

[garbo]

Just curious is it supplied by natural gas ? We had a 1,000 KW natural gas generator in a 20 story office building. Even with all the ATS 'S on emergency power on a Sunday morning load was so light that generator voltage was running high and therefore none if the era's would retransfer after the normal 30 minute test run. Cat tech said that this seldom occurs on diesel generators. Tech tried making adjustments but finally told us to run load bank during every test.

 

[Hv&Lv]

Agreed. Put a load bank on it and check it.