Current Harmonics and Chiller motors

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R

Red Wiggler

Senior Member
We have a new Chiller that continues to "trip" with history showing Phase reversal, Loss of Phase, High current etc.

So far we cannot determine the problem. The chiller is fed from breaker in a Main Switchboard directly to a Ground Fault Breaker in the Trane unit (Chiller).

It has been mentioned there could be a problem with Ground Fault, which could be a Chiller problem. (But I am not sure)

Others have mentioned "Current Harmonics". I don't know anything about Current Harmonics and the effects they have on Chiller motors.

Can anyone offer any help?
 
brian john

brian john

Senior Member
Location
Leesburg, VA
If it is the controller replace the controller had this problem at three different sites, they blamed everything except the root cause, which was the controller.
 
weressl

weressl

Esteemed Member
Location
Texas by the Gulf, geat crab, great shrimp
Red Wiggler said:
We have a new Chiller that continues to "trip" with history showing Phase reversal, Loss of Phase, High current etc.

So far we cannot determine the problem. The chiller is fed from breaker in a Main Switchboard directly to a Ground Fault Breaker in the Trane unit (Chiller).

It has been mentioned there could be a problem with Ground Fault, which could be a Chiller problem. (But I am not sure)

Others have mentioned "Current Harmonics". I don't know anything about Current Harmonics and the effects they have on Chiller motors.

Can anyone offer any help?
Click to expand...

It could be both. GF relays can go haywire with high harmonic content and even more so when operated on a resistance grounded system WITH high harmonic content. High harmonic content could be from large rectifiers, nonlinear power supplies, capacitors, ASDs and UPSs, and masses of magnetic, conventional ballasts.
 
brian john

brian john

Senior Member
Location
Leesburg, VA
Verify the settings and operation of the GF protected CB, have the CB tested.
Perform or have someone perform a PQ study to include trending current and voltage harmonic distortion.

The chiller manufacture will typically want this completed, prior to them assuming any responsibility for the problems at hand.
 
R

Red Wiggler

Senior Member
Current Harmonics

Current Harmonics

The Chiller rep believes the problem lies with us (electrical Contractor). We provided the service from the Main Switchboard (Pipe and wire).

The GF Breaker is located in the Chiller, we landed our feeder wires to this breaker. We tested our wires (meggered) phased them properly, and tested voltage at start-up. (Single point termination)

Originally the chiller did not have a GF breaker. It was replaced by the GF Breaker when the chiller began having problems. (This is a brand new installation)

The Chiller people continue to believe we have problems on our end. We installed a chart recorder for approx 4 days and noticed during the late afternoon there was problems with the current. We submitted the readings to the POCO and they denied any fault on their end...

We did see some problems with the current harmonics, and that has lead me to ask the original question.

The General Contractor believes we (we are their sub) should expend the necessary resources to prove that it isn't our problem.

I say the Chiller company should prove that it is our problem.
 
RoberteFuhr

RoberteFuhr

Member
Location
Covington, WA.
:-?

It is common for manufactures to blame the contractor or utility for problems that they have with their equipment. The only way to prove them wrong is to rent (or hire a power quality consultant) a three phase high speed power analyizer meter. These meters will record current and voltage over time and will capture the tripping event. You can then see exactly what the voltage and current are at the time of the trip. We use the Fluke/RPM meters.
 
D

__dan

Banned
I looked at some Carrier Evergreen XRV chillers that would trip twice monthly or so for utility power blips.

It was obvious to me the control boards were fed from a control transformer with no filtration, straight from the utility 480 v chiller feed. I recommended putting the control board power on a line conditioner or UPS, ~ 50 watts. I was thinking the chiller should stay on and the rectifier front end to the chiller VFD should not be too fussy about what it eats. The control board was tripping, not the VFD.

Using the process of elimination and trying to eliminate the easy stuff first, I figured the control boards were getting confused or lost when the power blipped. Once the guys got the idea it might be something simple, they got comfortable resetting the chillers. They did not want me to try to put through an engineering change with Carrier. They had been considering putting the whole chiller plant on a UPS, 1 MW.
 
D

__dan

Banned
If the chiller has a VFD on the main drive motor, the current harmonics (sinewave distortion) are being generated by the load, some distortion is normal for the load.
 
brian john

brian john

Senior Member
Location
Leesburg, VA
What level of current harmoonics?

What is the level of voltage harmonics?

HOW or WHY do some feel the GFP CB is involved, is this CB tripping?

As noted is there a softstart of VFD on the chiller.

Are there other VFDs in the facility?

If this is a current issue (not saying it is by any means) it is either a design issue or possible an equipment issue with the chiller or possibly with lack of or defective input filters on drives. AMONG MANY OTHER POSSIBLE PROBLEMS.

Who is reviewing your chart recorder and what makes them the expert?

What I would do:
Prove the voltage is acceptable to the GC and HVAC contractor.
Show your installation meets design specs.
Show your megger test sheets.
Measure VD from the service to the chiller terminals.
Tell them at this point you have met your obligations and any additional investigations will cost them CASH IN THE HAND.
 
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