YCAS140 Motor Current Issue

[jayguy]

YCAS0140EC46YFADBXXXXXXLXXXX45XXXXXXXXXVXAXXXXX7XX XXXXE

Started in June 2001, 460/3/60

116 RLA (both compressors), 125 is the IOM FLA

the problem is that the compressor is drawing 62-63 AAC. The display says 57 amps @ 47% FLA. The I/O Board is displaying 1.3 VDC. I am measuring 1.4374 VDC at the I/O board...everything is very steady (amps and VDC).

why?

i checked the programming and it is set to 125 @ 100%. the MP is set to 3.46 as per the IOM as well. both compressors are the same model number and both of the VDC from the MP read higher than the display shows and by about the same amount.

also, dip switch setting #5 shows 'Motor Current Averaging Enabled' no matter how i set it or how many times i cycle power.

what am i missing? i am sure there is something. i hate having the controls think that the amp draw is lower than actual. a couple of amps, ok, but 6-7 and i saw it was 10 at one time. i have used 3 different meters to measure it and all 3 are within 1 amp or less.

[york56]

Program side looks ok wye delta chiller name plate 116 , two leads per phase through mp , 100% fla 0f system 125 , mp point voltage 3.46
dip switch 128=1 , 64=0 , 32=0 , 16=1 , 8=1 , 4=1 , 2=0 , 1=1 thats what it should. info. out of form #201.19-nm1 (204)

[jayguy]

...dip switch 128=1 , 64=0 , 32=0 , 16=1 , 8=1 , 4=1 , 2=0 , 1=1 thats what it should. info. out of form #201.19-nm1 (204)

that is the iom (i may have gotten it from you) says and that is what the dip switches are set to...what am i missing? what else is there to check? if the amp draw was reading high, i would be less worried.

[york56]

Are both compressors doing this or just onr specific , if its only one try changing mp modules see if it follows. Looks like you have everything else set right unless there is a moduule acting up. Nothing else to really set Jay

[jayguy]

both compressors have the error and they both read low. i am not familiar enough with this control to make a judgement call without more info on what part is bad or if a board is programmed right.

about a month ago, i got these numbers....
Compressor #1 measures an average of 91.093 amps. York display reads 78 amps.
The MP signal is 2.0528 VDC. (I don't know what the York display read...hadn't got that far in the IOM yet)
2.0528 VDC = 95.18 amps (0 VDC = 0 amps, 5.5 VDC = 225 amps)

this week, i got these numbers after changing out this compressor...
Compressor #2 measures an average of 62.133 amps. York display reads 57 amps.
The MP signal is 1.4374 VDC. York display reads 1.3 VDC.
1.4374 VDC = 58.80 amps (0 VDC = 0 amps, 5.5 VDC = 225 amps)

it appears that there are 3 things to conclude...
1. it seems as if compressor #1 MP is ok since the math appears to be correct.
2. it also seems that compressor #2 MP has failed since the math is incorrect.
3. it appears that the I/O board is incorrect for both.

2 questions...
1. is my math correct (at least is my York math correct, is this how they would process the numbers)?
2. is my reasoning correct? 1 failed MP and 1 failed I/O board?

we just took over this account about a month ago so i do not have any history to go by.

thanks!

[klove]

You can reset your DC input voltage setting under "XXX volts DC = 100% FLA" to change the amp reading if you're off slightly. Change a little under steady state operation to see which way it goes and what the gain is, and then make your final adjustment.

[york56]

Just looking at some of the IOM's comparing data and reference the machine you have is a F series back in the day they would calculate the compressor FLA by this # 1.2 times RLA now the book we are both looking at is for a G series but the compressors tonage numbers are the same as which are the dip switch settings and they use 1.08 times RLA so if you do the math the 1.2* RLA = 139.2 and the other one 1.08* RLA = 125.28 so these would be the numbers for 100% FLA of system and the MP input voltage for 139.2 is 3.84 and 125.28 is 3.49 go in with the high level code and plug some of these numbers in and see what you get , remember what you see on the display is as they say in the book (approximate readings ) verify what you see with your amp clamp to display reading.

[jayguy]

thanks guys! i will not get back there until next week.

doesn't this seem kinda complicated? why does York do it this way?

[york56]

Not sure why they do it this way but everytime I spoke to one of them they seem like there trying to figure out what formula to use themselves good luck.

[klove]

thanks guys! i will not get back there until next week.

doesn't this seem kinda complicated? why does York do it this way?

I think they surmised that if they didn't make it as complicated as was humanly possible that the Trane guys could fix it, too........:angel::angel:



Just kiddin', jay!!! I've often wondered the same thing myself.

[jayguy]

got back to the job today...amps still read lower than actual but only by about 5 amps...which isn't much but, by percentages, it is 8-10%.

too many other problems to worry about it much. i will probably revisit the issue in the Spring.

thank you everybody!