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Need troubleshooting on 5H-60 compressor

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hvacdoctor

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Discussion starter · #1 ·
Have an old Carrier 5H-60 open drive compressor with a 50 HP 1750 rpm motor. Unit was overhauled 2 years ago, on old ACME chiller. Getting high motor amperage rated for 110 amps running at 124-125 amps full load and if head pressure gets up over 270psi amps will go up to 150... Checked voltage and phases ok, adjusted water regulator to keep 200psi or so head pressure ok, running low suction around 50psi give or take. Load is very low on this chiller. Would like to adjust internal unloader but cant find any info on this old puppy. Called local Carrier they want to mail me an manual but that will take a week or so. Motor was also rebuilt last year with compressor.
 
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#4 ·
On the end opposite from the motor you will see a cap which is covering the adjusting knob for the unloader. Underneath is a stem. Turning the stem all the way counterclockwise will load the compressor completely. So you need to start turning the stem clockwise to reduce the current draw on the motor to an acceptable level. You will defenitely hear the compressor as it loads and unloads. This will also help with your low suction pressure. If you need any more info just let me know, I am looking at a manual published in 1951. regards
 
#8 ·
A 50hp motor is not big enough for a 5H-60 on R-22 running fully loaded.

Has this unit been converted from another refrigerant? Some people in the past converted a R12 or R500 machine to R22, but if you do this you must remove suction valves to derate the compressor. It is better to convert to a blend. That head pressure sounds awfully high for this application. If the compressor was originally on another refrigrant then it was not 60 tons and the cooling tower may not be 60 tons either.

Has the motor been changed? Could the 50 be a replacement motor that should have been a 60?
 
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#10 ·
head pressure should never be over 225. scaling increases at a higher rate over this pressure. also 5hs use a hydrolic unloader. there should be a cap on the lower side of compressor. also unloader should unload at 55 lbs. high also should run a net oil pressure of 50 and that is loaded. also you should charge to 10 degrees subcooling and adjust superheat to around 20. high head pressure causes high amps also overcharge will do the same.
i would also call carrier tech support and find out if the motor is large enough.
 
#12 ·
mike grab said:
so what you guys are saying is in the case of said 5h-60 the 60 corisponds with 60 tons? i have been working on 2 5h-40's so they are 40 tons a peice? if corect that seems easy.
Click to expand...
This only holds true for R22 and if the compressor is loading on all cylinders. On other refrigerants the tonnage will be less and if someone has pulled suction valves the tonnage will be less.
 
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Discussion starter · #13 ·
Thanks for Info!!! Very Helpfull We got the unloader adjusted seems to be working but were still over amping the motor. The motor rebuilder wanted us to disconnect the coupling to test the motor???? In process of doing this. Is there anyway to install electric unloaders to this compressor?
 
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#14 ·
No, this compressor is hydrylic only. You can use pneumatics to control the unloader. Be careful with the coupling, it is an art to get it apart and back together and if the motor and crankshaft are not aligned properly it will take the seal out of the compressor. Again, 50hp motor is to small and I am sure this is why it is over amping.
 
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#15 ·
There is a way to convert the existing hydraulic unloaders to electric unloading controlnbut it may require tapping some holes into the handhole cover depending on the serial number of your comressor. If you can get a copy of 5F, H Application Data manual, catalog no 510-503, the procedure is outlined in detail.
 
#16 ·
you need to perform a megohm test on the windings of this
motor.test the leads to each other and to ground.check the
bearing temps and clearances on the motor.check alignment of
motor shaft to compressor shaft if the alignment is off due
to last rebuild the added resistance of the metal coupler
and axial pressure on bearings could drive motor amps up.
a tell tale sign of misalignment is shaft seal leak.
check the starter as well. any short or slight shorts
to ground will help drive amps up.
 
#18 ·
5h compressor

Hey dude,
you may want to check the spring in the adjustment cavity and make sure that it is an r-22 spring, if it was converted may still have old spring - there is a number on the spring that states the refrigerant and it will also tell you this in the adjustment section of the IOM.
 
#19 ·
Carrier data: 5H60

R-22, water cooled condenser:

100degree cond.
40degree evap.
65.9 tons
56.1hp

100degree cond.
30degree evap.
52.9 tons
53.5hp

105degree cond.
40degree evap
63.7 tons
58.8hp

105degree cond.
30degree evap.
51.0 tons
55.6hp
 
Discussion starter · #20 ·
We adjusted the unloader operation, motor amperage is fairly steady now around 112 amps.
 
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