hvac problem or electrical ?

[etheric999]

i have a building with a ton of florida heat pumps,cooling tower, and heat exchanger,heat is rejected into the hot water loop from the heat pumps and the heat exchanger transfer the heated water into the tower loop so i need the hot water circulating pump running in order to get some cooling going.problem is i have two hot water circulating pumps with mitsubishi drives that keep knocking the whole building out. the pumps run about 8 minutes then trip the building,the drives were checked by mitsubishi and checked out ok,the electrician changed the gfi in the main panel(set at 240 but its tripping out at about 99),the pumps ran about two weeks and then bam trips the whole building again,any suggestions? (the motors are baldor 25 HP,230/460 3 phase,1770 rpm,60/30 amps)

[supertek65]

yeah
why is it drawing 99 amps???????????????

are the pumps running the wrong direction??????????????????



i have a building with a ton of florida heat pumps,cooling tower, and heat exchanger,heat is rejected into the hot water loop from the heat pumps and the heat exchanger transfer the heated water into the tower loop so i need the hot water circulating pump running in order to get some cooling going.problem is i have two hot water circulating pumps with mitsubishi drives that keep knocking the whole building out. the pumps run about 8 minutes then trip the building,the drives were checked by mitsubishi and checked out ok,the electrician changed the gfi in the main panel(set at 240 but its tripping out at about 99),the pumps ran about two weeks and then bam trips the whole building again,any suggestions? (the motors are baldor 25 HP,230/460 3 phase,1770 rpm,60/30 amps)

[supertek65]

are they 230 or 460 volts????????????????????????????????????????????? ??


i have a building with a ton of florida heat pumps,cooling tower, and heat exchanger,heat is rejected into the hot water loop from the heat pumps and the heat exchanger transfer the heated water into the tower loop so i need the hot water circulating pump running in order to get some cooling going.problem is i have two hot water circulating pumps with mitsubishi drives that keep knocking the whole building out. the pumps run about 8 minutes then trip the building,the drives were checked by mitsubishi and checked out ok,the electrician changed the gfi in the main panel(set at 240 but its tripping out at about 99),the pumps ran about two weeks and then bam trips the whole building again,any suggestions? (the motors are baldor 25 HP,230/460 3 phase,1770 rpm,60/30 amps)

[supertek65]

how many amps are each individual pumps/drives drawing and what is the exact voltage??

what are your accel times set at??????????????????

you have an adjustable main breaker??? or is it a shunt trip breaker????????????????

[flange]

I think your best move would be to have me send out a service tech who knows not only drives, but building systems, who can look at your overall system and help you get to the root of the problem. Seriously why are your gfi's tripping at 99 if they are allegedly set for 240? do you have a drive fault at all? which mitsu drives the funky industrial ones? are you in south jersey by the way, home of the poor power factor and voltage imbalance?

[Tommy1010]

are you in south jersey by the way, home of the poor power factor and voltage imbalance?
lmao.....:tank:

[Knife Switch]

It's weird they ran ok for 2 weeks then tripped it.. Did they trip the building on startup?

[maxster]

do you walk in and the VFD is tripped? if it is i could be something expernal from the hvac power ..parking light loads coming on, interior lights turning on,elevator loads spiking back into the inverter.do you hand/auto/off control the VFDs for the pumps

[coolerinfrederick]

if it's the main panel are you sure it's the pumps tripping it, i'd think the vfd would trip out on some fault before blowing the main, i'd check what maxster said

[flange]

many areas of jersey have power quality issues, and can play havoc with vfd's. the thing is, you are tripping the gfi, not the drive right? the way i read your explanation, you trip the gfi at 99 amps when rated at 240. you then have issues with tripping the main but so far i dont see a vfd fault indicated. To knock out your building main and not the gfi or the vfd usually requires a dead short or really crappy power. My guess is short somewhere, and its intermittent. could be a nicked wire that comes into contact due to vibration or something like that, water getting where it doesnt belong when it rains, or some really intermittent load that you dont know about that makes it seem like the pumps. sounds like you are gonna have fun with this one. just curious, how far are the vfds from the motors?

[harv]

Sounds like the drives are set up wrong for your application. best quess of the day.