HP motor contactors dropping out when 3 or more bays using at same time.

[Dan-Ark]

Had the busiest day yet since renovating this old wash (D&S pump stands). today when I arrived at the site. 3 bays in use, all running High pressure. the pumps were starting and stopping intermitently. Went to the equipment room suspecting maybe a water supply issue, but the contactors were dropping out and pulling back in, all 3 at same time. Each bay has own 24v transformer, contactor and 3 phase power from main breaker panel. I shut down the bays and tightend the terminals on the contactors and transformers. I did get a slight movement on my screwdriver on a couple terminals but not really loose. Each bay runs fine if only one or 2 are on at the same time. My guess is I"m loosing one leg of my 3 phase perhaps due to load of 3 or more of the 5hp pump motors running at the same time, it would seem to me it would have to be the one of the legs that the 24v transformers use and that is cousing 24v to drop out and release the coil on the contactor. Before I shut down the whole wash to check inside the breaker box, I thought I'd ask for other ideas here? anyone? It did it twice today while I was there. only data so far is first time it was bay 1, 3 and 4 running and second time it was 2 3 and 4.

 

[Dan-Ark]

One more piece if info. the IBA with 25HP pump motor starts and runs fine off same breaker box.

 

[MEP001]

I've seen something like that happen when the phases weren't matched between the bays and all the 24V "commons" were interconnected. Try checking across the transformers - you should read no voltage between the left input of bay 1 and the left input of bay 2, same with the right inputs. Check down the line (bay 2 and 3, etc) both the input and the 24V output.

 

[wash4me]

maybe the low water cutoff sensor is bad?
Basically you need to put a meter on A1 and A2 of the coil and see the voltage drop out then follow it to it's source and see where it drops voltage.

 

[Randy]

Did this problem just start? Did you happen to look inside the water supply tank to see if the water level was above the low water cutout? I'd start all the bays and try to make it act up again and then check the water level in the tank. Then get out the volt meter ad start checking the voltage.

 

[Dan-Ark]

Found it this evening. there is a float switch in the rinse tank when 3 bays are using high pressure, there is not enough water coming in to fill the tank. guess I get to learn to rebuild one of those watts diaphram valves. found 2 used ones and a couple new diaphrams in the storage shed...

 

[Dan-Ark]

I appreciate all the help you guys have given over this first year. I will say one thing I've learned.. I now love pollen! this probem only came up because we got so busy. guess never had all 4 bays in use at same time with 3 using HP. that or whatever is blocking the valve has built up enough to restrict the flow now that we have been open a few months.