ATS In-Phase Monitor Question

[ATSman]

I received a PM from a member and thought the info might merit posting here.

Hi ATSman,

i have a Kohler 300KW genset paired with a Kohler ATS. Currently the engine is running at 60.0HZ and the InPhase Monitor is disabled. The ATS is standard transition not programmed transition.

I'm going to install a remote speed adjust switch and set the frequency to 60.1 or 60.2 and enable the InPhase Monitor.

The next step is a struggle for me. The MPAC1000 ATS controller has the ability to adjust the phase angle from -20 to 20 degrees. What is this actually setting? What should it be set at? Should it be leading or lagging? The factory default is 0.

The reason for setting this this up is during hot to hot transfers via the test button HVAC relays fail/burn up per site tech. The main load of the facility is lighting, elevators and HVAC.

Thanks!

Gen Tech
Sounds like you are headed in the right direction. On the MPAC1000 the -20 to +20 degree range represents the sync window in electrical degrees. If you monitored the sign waves of the two sources on a scope you would see the sign waves moving in and out of phase. When both waves are on top of each other (in phase) they are at 0 degrees apart or perfectly synced. We typically set this at between 10 to 15 degrees and the gen frequency to 60.20 HZ which results in a good sweep time (the speed the sign waves pass each other.) The gen frequency could also be set at 59.8 HZ, as long as you maintain the 0.2 HZ differential. In worse case when the gen is set at exactly 60.00 HZ the sweep time is very slow and in some cases the gen never syncs to the utility and time-out occurs (ATS lock-out.)
Let me know if I have explained it clearly enough. This is a good question and I think it would be useful info to others if I posted it.

PS: I remember working on the same system with the same problem. I was amazed to find out that the speed of the Kohler gen came fixed at 60.00 HZ and that an optional speed adjust module had to be ordered/ installed for us to activate the ATS inphase monitor feature.
Oh, bring back the old days when most gens came with a pot on the control panel door for adjusting the speed!! :rant:

 

[Jberg73]

I came across the same issue when installing the kohler. I was amazed that the module was a separate purchase. Then I got to thinking that all manufacturers are doing that now a days. Eaton being the worst when it comes to wanting to use different functions on their equipment. Most notably their UPS systems. Good info, thank you for sharing.

Jason

 

[ATSman]

I came across the same issue when installing the kohler. I was amazed that the module was a separate purchase. Then I got to thinking that all manufacturers are doing that now a days. Eaton being the worst when it comes to wanting to use different functions on their equipment. Most notably their UPS systems. Good info, thank you for sharing.

Jason

Yeah,
Anyway for the big corps to boost their profits, they will find it!! :rant:

 

[steve66]

I wasn't aware that the frequency was adjustable. Is that typical for most generators, or just the Kohlers?

I thought the generator frequency always had enough drift that it would synch., although it might take a few minutes.

 

[ron]

It is because of this type of load during open transition, and the motor loads ramping down, and the in-phase monitor only checks the relative phase angle between sources but not any backfeed that may be happening from the motor spinning down, I specify Delayed Transfer ATSs.

 

[ATSman]

I wasn't aware that the frequency was adjustable. Is that typical for most generators, or just the Kohlers?

I thought the generator frequency always had enough drift that it would synch., although it might take a few minutes.

Most gensets either have governors that can be adjusted or have an option package that can be ordered and installed for that purpose.

Not correct, especially with the larger (500KW and above) newer units which normally come factory set dead on at 60.00HZ.
Also, most ATS controllers have a mechanical lock-out timer (typically 60 sec) that will abort transfer if the gen does not sync in a certain time window.