Differential Current

[successwale]

iam running a gas generator of 1.5MW Duetz engine which indicting Differetial Current from the control panel.what might be the causes and solution to this problem?

 

[marks1080]

Is the unit tripping off?

 

[successwale]

yes,the unit is tripping?

 

[dpc]

Well, a little more information would be helpful. If all the current transformers are correctly connected to the relay, operation of the differential relay indicates an internal winding fault inside the generator, or at least in the differential zone.

If this is a new installation, I would strongly suspect incorrect wiring or phasing of the CTs.

If the unit had been running successfully and no wiring changes were recently made, you have to assume there is a problem in the generator. You should shut down, isolate the generator, and do at least a megger test and polarization index.

 

[esee135]

If you have good relay maintenance, the 87 differential is your worst day come true.

Generally it will mean that you have experienced a fault between your differential CT's. 87 is very reliable when you have cases of a line to ground fault in the stator. Look for cable termination kit failures, transformer failures, anything between the CT's.

I would start with a visual, then begin isolating the bus and start megger testing until you find your fault.

 

[ScottyUK]

Split the stator windings so each is isolated from the others and from the plant. Megger winding-core and winding-winding for each winding. You will probably find the problem during this test if it is a true fault condition and not a problem caused by mis-wiring as DPC noted.

Is this an LV or MV machine?


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

 

[Hoxton]

Can you post a single line diagram, showing the protection? If not, I can post a typical one and you can mark it up.