Vac won't shut off.

[IMcarwash]

I have a industrial vac that from time to time will not shut off after the time has ran out, I've changed relay, and the timer what am I overlooking?

 

[MEP001]

What kind of timer and relay does it have?

 

[Randy]

What do you have to do to get it to shut off?

 

[eckert16]

check wiring...specifically the 'latching'

 

[IMcarwash]

Timer is dixmor led7. Relay is a Dayton 24 volt I call ice cube

 

[IMcarwash]

What do you have to do to get it to shut off?

I pull out the relay

 

[IMcarwash]

What do you have to do to get it to shut off?

check wiring...specifically the 'latching'

check wiring...specifically the 'latching'

ITS THE SAME AS THE OTHER VACS, EVERYTHING SEEMS TIGHT.

 

[Randy]

I'd swap the LED-7 timer and the relay from another vacuum to the vac that's acting up.

 

[MEP001]

If the vac stays running, first thing to do is unplug the timer. If it still runs, the relay is bad. If it shuts off when you unplug the timer, the timer is bad (Unlikely but it does happen). Pulling the relay will always shut off the motors no matter what, so that's no test of the problem. The relay is probably bad, but check the timer first to be 100% sure. I recommend upgrading to a 35 amp mercury relay.

 

[Earl Weiss]

If it is a mechanical coin switch you may not have the correct terminals connected.

 

[IMcarwash]

If the vac stays running, first thing to do is unplug the timer. If it still runs, the relay is bad. If it shuts off when you unplug the timer, the timer is bad (Unlikely but it does happen). Pulling the relay will always shut off the motors no matter what, so that's no test of the problem. The relay is probably bad, but check the timer first to be 100% sure. I recommend upgrading to a 35 amp mercury relay.

This sounds good, I’ll get a 20 or 30 amp relay, where did you find yours at?

 

[MEP001]

https://www.kleen-ritecorp.com/p-50-mercury-35no-24ath-normally-open-relay-for-inductive-or-lighting-loads-24v-35-amp-1-pole.aspx

Did you try anything suggested to see what is wrong?

 

[IMcarwash]

Yes, I had already tried everything suggested the larger relay makes sense, my vacs have 3 motors they came with three 7.2 amp motors but somewhere along the way I put in a 10.2 amp for one of the motors, I have other vacs the same way with no problem.

 

[eckert16]

interesting data point... one of your vacuums broke... Typical troublshooting step is to compare multiple 'like systems' onsite to ease the diagnostics. When asked about the vacuum systems setup you said
"ITS THE SAME AS THE OTHER VACS, EVERYTHING SEEMS TIGHT"

Thank you for sharing the resolution of the problem. Part of the original problematic vacuum was the setup, it wasn't setup the 'same' as all the other vacuums on your site because at some point you changed the operating parameters of the problematic vacuum, as you:
"put in a 10.2 amp for one of the motors, I have other vacs the same way with no problem"

Recommend you make the same 'resolution' to prevent this problem from occurring to the other vacuums on site that you have also installed a different 10.2 am motor in:
"I have other vacs the same way with no problem" ...

With this experience, do you think it likely other modified vacuums on site may fail?

 

[MEP001]

my vacs have 3 motors they came with three 7.2 amp motors but somewhere along the way I put in a 10.2 amp for one of the motors

This sounds good, I’ll get a 20 or 30 amp relay

You are running three 7.2 amp motors at a total of 21.6 amps. What size is your current relay? 15 amp?

With two 7.2 amp motors and one 10.2 amp motor, you are pulling probably 80 amps when the vac starts. It's no surprise that you've toasted the relay.

 

[1carwash1]

I had a similar if not the same problem with some new IVS vacuums I purchased around 2000. Sometimes when I arrived at the car wash one of the vacuums would be running continuously even though the timer says to input quarters. When I removed the dome and tapped the relay the vacuum would shut off. I suspected that the relays were fusing closed from the rush of current and/or the arcing of the closing contacts. Ultimately, after numerous instances of my vacuums running for hours on end, I decided to remove the relays and install mercury contactors.
After installing the mercury contactors the problem went away.

 

[Keno]

... I recommend upgrading to a 35 amp mercury relay.

I have seen these recommended multiple times on these forums. Any reason these are recommended instead of contactors? Curious as to why mercury relays are better for this application?

 

[Randy]

I have seen these recommended multiple times on these forums. Any reason these are recommended instead of contactors? Curious as to why mercury relays are better for this application?

I was first introduced to mercury relays/contactors about 40 years ago and we’ve been using them ever since. Inside the mercury relay there is a small pool of mercury, when the relay is energized the plunger is pulled down into the pool of mercury completing the circuit. With a regular contactor you have points that will arc and over time burn out. I’ve never had to replace a mercury relay. If you install the mercury relay on your vac and have the timer control the relay your timer will last almost forever since the timer is only activating the coil on the relay. I haven’t replaced a vac timer in over 15 years

 

[Keno]

I was first introduced to mercury relays/contactors about 40 years ago and we’ve been using them ever since. Inside the mercury relay there is a small pool of mercury, when the relay is energized the plunger is pulled down into the pool of mercury completing the circuit. With a regular contactor you have points that will arc and over time burn out. I’ve never had to replace a mercury relay. If you install the mercury relay on your vac and have the timer control the relay your timer will last almost forever since the timer is only activating the coil on the relay. I haven’t replaced a vac timer in over 15 years

Sounds reasonable for your situation where you already have the mercury relays in operation. For me, contactors are readily available and cheap, also I have contactors on hand most times. Quality contactors cycle thousands of times per summer and last a decade or more in Air Conditioners. I would probably prefer to use a contactor just due to ease of logistics and using what I already have spares available for.

 

[Earl Weiss]

I. If you install the mercury relay on your vac and have the timer control the relay your timer will last almost forever since the timer is only activating the coil on the relay. I haven’t replaced a vac timer in over 15 years

True, I've still got the Brown Paraplate timers s with the large screw head terminals in a bunch of vacuums set up like this.