hitachi chiller

[ncmorgan]

hi i was having a problem with high amps on the chillers compressor ,also i had 11.c going into condensor (water cooled ) and 36 coming out.
i thought it was just the regulating valve for the flow causing the problem.
but with the high tds across the condensor coil would this be the cause

[nike123]

36 coming out seems OK!
You need more measurements!
Superheat, subcool, TD at evaporator , pressures etc...

[The Viking]

Any chance we could get a bit more information?

Model No.?
Pressures?
Subcooling?
Superheat?
Chilled water in/out?

Would be a good start......


We are good but not that good and definitely not psychic...

[ncmorgan]

hi yeah didint get chance to get all facts as
chiller would trip out on overload 90 amps before i
could get a chance to get everything
5 bar suction 16 bar discharge
11.c in , 36.c out ( condensor)
set point was 9.c with 19 return evap

[nike123]

hi yeah didint get chance to get all facts as
chiller would trip out on overload 90 amps before i
could get a chance to get everything
5 bar suction 16 bar discharge
11.c in , 36.c out ( condensor)
set point was 9.c with 19 return evap

Did you checked crankcase heater? Did you energized heater at least 12-24 hours before start of compressor? Did you checked presence of all 3 phases and voltage balance at compressor terminal ( no more then 5% difference)?

[ncmorgan]

Did you checked crankcase heater? Did you energized heater at least 12-24 hours before start of compressor? Did you checked presence of all 3 phases and voltage balance at compressor terminal ( no more then 5% difference)?

yeah all 3 phases fine, plant is about 8 years old
and crankcase heaters on,plant flow for condensor
water is all ok,no history of blocked condensor.
i do think for a water cooled condensor 25.c across
the coil is a bit high,thats why i thought the flow reg was not operating fully and causing not enough flow though condensor,causing high hp and amps

[The Viking]

Did it sound normal?
Is the windings' resistances normal?
Does it megger out OK?
Is the voltage OK on all 3 phases at the compressor's terminals?

If it drops out on overload before you get a chance to check how it's running, then you are most likely looking for a problem with the compressor itself or the power supply to it.

(Lack of flow through the condensor will cause a HP trip, and 16 Bar is not excessive in a "normal" installation)

[ncmorgan]

Did it sound normal?
Is the windings' resistances normal?
Does it megger out OK?
Is the voltage OK on all 3 phases at the compressor's terminals?

If it drops out on overload before it gets you get a chance to check how it's running, then you are most likely looking for a problem with the compressor itself.

yeah done all that ,all ok and checked,back on mon with new reg to see if it works let you know.
thanks for all your help

[bobjob]

hi i was having a problem with high amps on the chillers compressor ,also i had 11.c going into condensor (water cooled ) and 36 coming out.
i thought it was just the regulating valve for the flow causing the problem.
but with the high tds across the condensor coil would this be the cause

Is the compressor fully loaded on running ?


you need to make sure the compressor is running unloaded for some time and then bring compressor up to its full 100% capacity.

regards bobjob

[nike123]

yeah all 3 phases fine, plant is about 8 years old
and crankcase heaters on,plant flow for condensor
water is all ok,no history of blocked condensor.
i do think for a water cooled condensor 25.c across
the coil is a bit high,thats why i thought the flow reg was not operating fully and causing not enough flow though condensor,causing high hp and amps

You have 25K across the coil because the water regulating valve works his job. Entering temperature of water is low, and flow is reduced, in order to pressure in condenser stay at 16 bar, as adjusted at valve.
That confirms water temperature of 36°C at outlet of condenser.
If, for example, entering water temperature of 25°C is the case, outlet water temperature with correctly functioning valve should stay at 36°C but water flow will be much higher.

[mgtet]

sounds like the compressor requires a bearing overhaul. Check oil level first. I would also disconnect the compressor leads off the contactors and check the voltages there to ensure you have no faulty contactors.

[andy c]

Hiya, Have you tried running the compressor with only 50 or 75% load for 10mins or so. You should be able to get an idea of what is causing the trip, Have you got a decent superheat. Is the refrigerant charge correct. Have you checked the water strainer for blockage.although the 25oC differential across condenser is not too high. Have you got a dodgy contactor or overload. It might be wise to have condition monitoring on the compressor to see if there is wear on the bearings. A bit expensive to have this done but will tell you if a bearing is on its way out. What run hours has the compressor done, and has it been overhauled in its life. I think it's every 12000hrs for a Hitachi screw, but don't quote me on that. We have a site with 9 of these and have the compressors monitored every six months, we have just started getting significant bearing wear on one of them. Regards, Andy C.

[ncmorgan]

hi all just to let you know,my problem was a simple one.it was just a faulty condensor water regulator that wasnt opening correctly,changed regulator and found everything ran sweet.
thanks for all your replys ,happy fixing

[nike123]

hi all just to let you know,my problem was a simple one.it was just a faulty condensor water regulator that wasnt opening correctly,changed regulator and found everything ran sweet.
thanks for all your replys ,happy fixing

I am confused.

Does that mean that valve has not regulated condensation at all the operation times and that sometimes tripped high amperage protection, or condensation temperature of refrigerant at 16 bar was to high for that chiller.
What refrigerant is in that chiller?