Cummins - QSK60/600V/2000ekW intermittent start-up 1

[CanuckEngineer]

Hey guys,

I have a Cummins QSK60 - 600V - 2000EKW diesel generator set at one of our sites.

It is a standby generator set for an office building.

The generator feeds, qty;4, BTPCB Cummins-Onan model ATS'.

Recently, the generator has been intermittently starting up on its one without any enabling from any of the ATS.

The ATS are connected via dry contact to the start circuit of the Generator. During these incidents not one of the ATS show a loss of utility feed and thereby (at least it is assumed) the dry contact from the ATS is not enabled. However the Generator turns on and remains on for some time (in excess of an hour or so).

Upon reviewing the ATS logs, they do not transfer in any one of these incidents.

Can anyone recommend on what could be the issue.

I am thinking it might be the local genset controller although the generator technician is saying that he does not see any issues from his end.

The generator system was put into service about 4 months ago.

Your help is appreciated.

Thanks,

RK.

 

[waross]

Check the ATS settings.
Do one or more of the ATSs put a load on the gen-set?
Does the gen-set eventually turn off?
You may have one or more ATS set for periodic exercise.
Some transfer switches have a feature that can be enabled to require a manual transfer back to the utility.
Does the local controller have an exercise function?
Do you have very long conductor runs to one or more of the ATSs
Does one or all of the ATSs command the set on?

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

 

[CanuckEngineer]

Great questions Waross.

I don't know the answer to all of them but I like the idea of the exercise timer.

I am managing the project as a whole and I will need to talk to operations for answers.

I will post it to them for a response.

To answer your last one: all command the ATS on, basically if a feed is lost on any one of the ATS it will command the generator.

Thanks,

RK.

 

[CanuckEngineer]

Waross,

I don't have the scaled engineering drawings infront of me however I know that one of the ATS is in the basement meanwhile the Generator is on the mechanical penthouse, 42nd story.

So we are looking at a feeder run there of greater than 450 feet or so, 600V, 3 phase. 600A

Thanks,

RK.

 

[waross]

Hi. I'm not worried about the feeders. It's a long shot, but any time that we have really long control runs it may be wise to consider the possibility of leakage, induction from other sources or capacitance causing spurious signals. Some inputs put very little current through dry contacts and are sensitive to issues that would not bother an old school relay input.
A fairly important question in trouble shooting and worth asking again:
Does the set turn itself off eventually or does it have to be turned off manually?



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

 

[itsmoked]

Following up on the long wire run (which I'm betting is the problem) you could easily have the command wires running a long distance next to current carrying wires that will magnetically couple into the control wire. It will be 'mysterious' because you'll end up with a high enough coupling to command a start only when certain loads run in the parallel conductors. Perhaps when an A/C unit or a pump starts.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Is the control voltage AC or DC? Bad things happen with long control cables and AC control voltages, especially with high impedance inputs or small relays.

 

[CanuckEngineer]

Thanks for everyone's feedback.

To close up the thread it wound up being that one of the ATS' was sending an erroneous engine start signal.

They have since swapped out the ATS controller and the incident has not returned.

Thanks,

RK.

 

[ScottyUK]

than you for the follow-up. It's rare anyone bothers, but appreciated when someone does.

 

[CanuckEngineer]

No problem Scotty.

I think its only customary and professional to do so.

Regards,

RK.