Timer relay HELP

[atty]

I know I'm showing my age. This problem is simply one with semantics and nomenclature. I know the device is out there. I just can't seem to put together the right search words. We didn't have that many 40 years ago......'course we didn't have Search Engines either.

I need a power relay in series with a well pump. 220 VAC, say 6 to 8 amps, so we'll call the contact rating at 10A. Actually, I shouldn't say 220 VAC, necessarily, just a normally closed relay that senses "closed" on the motor contacts, then "monitors" the run time once energized. If it goes beyond 30 min., then it kicks open. Manual or automatic reset is optional. It can't be that hard, even if I have to rig an external relay, but I can't seem to pull it out what Google wants to see.

Any ideas on where I'm missing it?

[superUnknown]

You are looking for an off delay timer.

http://www.galco.com/shop/Time-Delay-Relays

http://www.automationdirect.com/adc/Shopping/Catalog/Relays_-z-_Timers/Timer_Relays_-z-_Counters_-z-_Tachometers

You will likely need to mount this to a relay base and click the base into DIN rail (standard electrical mounting rail)

Also, if you want to do some digging: sign up with TE.com (tyco electronics) they might send you a free sample or three...

[superUnknown]

If yer feelin lucky, here's a HUNG LO brand straight from Guandong Charlie's Flea-bay store:

http://www.ebay.com/itm/DIN-RAIL-DIGITAL-PROGRAMMABLE-220VAC-16A-TIMER-SWITCH-/280542290910?pt=LH_DefaultDomain_0&hash=item41519fa3de

[macona]

No, an off-delay relay activates after a set time after the input goes off. For this you want a pretty standard delay relay. This guy:

http://www.ebay.com/itm/Omron-H3CR-A-Time-Delay-Relay-100-240V-AS-IS-/220946485997?pt=LH_DefaultDomain_2&hash=item33716fd2ed

The pressure switch or whatever triggers this timer which triggers the pump contactor. After 30 minutes or whatever you set the timer for, the timer turns off the pump.

[KJ1I]

If I understand what the OP is looking for, it is a time limit relay. Its timer resets itself each time the unit turns itself off, unless it exceeds the set time, in which case the relay turns the unit off. He wants to turn the unit off if it runs continuously for 30 minutes. If it goes on for 3 minutes every 10 minutes during that half hour, that would be fine. If it ran for 29 minutes then shut itself off without the relay, that would be fine. Just don't let the unit run more than 30 minutes at any one time. The problem was the only time limit relays I could find were on Alibaba with order minimums of 100 pieces or more.

[jlevie]

This could be a little more complex than a simple than a time limit relay. Knowing the reason for limiting run time to 30 minutes would answer that. One possibility is that the goal is to deal with a broken pipe, valve, etc. With the 30 minute limit being picked as well more than normal usage. In that case once the time delay trips the pump needs to be disabled. That could be implemented with a simple timer and a latching relay for the pump power. The timer would break the relay coil current

[atty]

This could be a little more complex than a simple than a time limit relay. Knowing the reason for limiting run time to 30 minutes would answer that. One possibility is that the goal is to deal with a broken pipe, valve, etc. With the 30 minute limit being picked as well more than normal usage. In that case once the time delay trips the pump needs to be disabled. That could be implemented with a simple timer and a latching relay for the pump power. The timer would break the relay coil current

Your conjecture of the goal is pretty close, only it is primarily due to non-flow of water rather than something leaking. It is a standard 1/2 hp booster pump to handle the water from the storage tank to the house. Originally plumbed with PVC straight out of the pump that I have, over the years, replaced with steel pipe for a distance of about 18" in an effort to solve the problem, but no go. If, for any reason, the pump fails to shut off, the water has no place to go in the pump head and just sits there until it heats up enough to "melt" the PVC threads.....then the leaks begin. Over time, this pump has demonstrated an amazingly ability to find ways NOT to shut off. Every time I install a fail-safe, like a low pressure cutout on the suction side, or heat tape on the high pressure lines, it still finds another way to keep running. I finally decided the one and only way to insure that it does shut off before reaching critical mass, is to feed it through a timer. I would say the longest run cycle might be in the 15 to 20 min. range, so anything beyond 30 min. or so would indicate a problem.

It has been a war since 1999, and it is winning so far.

I appreciate the suggestions.

[ironmonger]

If the PE switch is still calling for the pump to turn on you might make sure the PE switch differential is set correctly. This could be the problem it self. Have you verified the on and off pressures of the PE switch?

Does the booster pump have a well type expansion tank?

If you need to shut off the pump when there is no flow I would look here:

http://www.ebay.com/itm/3-4-220V-250VAC-SPDT-Water-Flow-Paddle-Control-Switch-/221250943278

The flow switch closes the contacts as long as the water is flowing.
As the contacts would be open when the pump initially turns on, you could use a time delay relay,
see:

http://www.ebay.com/itm/POTTER-BRUMFIELD-CHB-38-70013-ADJUSTABLE-TIME-DELAY-1-180SEC-RELAY-240V-B223625-/300938314779?pt=LH_DefaultDomain_0&hash=item461152441b

and use those contacts in parallel with the flow switch. This will enable the pump regardless of flow for a desired time delay, say 2 seconds, and as long as the water is flowing after the TD relay drops out the pump will run. If the flow stops the flow switch will turn off the pump. If the PE switch does not drop out the time delay relay will not reset.

still seems that the problem may be in the pump controls.

paul

[Doozer]

I have used this one for many things...
McMaster Carr 6963K14
It is a multi-function timer relay you can program
to do just about anything. Delay on make, delay
on break, cyclical repeat, one shot, and a few more.
It is an Omron brand. You need a bigger contactor
to handle the pump current, but for what you are
trying to do with this well pump, I guarantee you
that this relay can do it. It is $150, but it might
save you from a burned out pump.

-Doozer

[Ridgerunner]

In this area something called a Coyote system is popular. In low performing wells water is pumped from the well to a storage tank as long as there is water in the well. The house supply is pumped from the tank. The idea of the system is as long as there is water in the well it can be pumped 24 hours a day; not just at peak demand times. If the well runs low on water the control unit senses this and shuts the pump off so it does not run dry.

[superUnknown]

I have used this one for many things...
McMaster Carr 6963K14
It is a multi-function timer relay you can program
to do just about anything. Delay on make, delay
on break, cyclical repeat, one shot, and a few more.
It is an Omron brand. You need a bigger contactor

-Doozer

Omron is a great option, good brand, robust.
Like the relay I originally posted.

http://www.galco.com/buy/Idec/RTE-P1AF20

$50.

[PStechPaul]

If the main problem is the overheating and melting the PVC, perhaps a simple surface thermostat would suffice.

[Bob Fisher]

Electronic sump pump controls may fit your need. They have variable run time built in and are triggered by the water level touching a wire. Not sure if the run time is long enough for your needs tho. Bob.

[Paul Alciatore]

Look here:

http://www.grainger.com/category/time-delay-relays/relays/electrical/ecatalog/N-8er?redirect=time+delay+relay

They have many "time delay relays". There are many other sources.

Here too:

http://www.mcmaster.com/#general-purpose-timer-relays/=qs4vx2

Search for "time delay relay".

You may have to use a 115 VAC model and just connect it between one 230 V leg and neutral or use a fixed resistor to drop the coil Voltage in half to 115 V. Pick one with normally closed contacts and connect it's coil to the lines between your existing contactor and the motor. Connect the normally closed contacts after that point and before the motor. That should work like you want. After 30 minutes or running, it should energize, open the lines to the motor, and stay energized until the main contactor opens up.

But there is no guarantee that, at the crucial time, this new relay will not fail.

[atty]

Thanks for the links and suggestions. They have given me fodder for the drawing board. A surface thermostat is something that I have pondered, and have not yet ruled out. Ambient temp. here in the desert can have a wide degree of fluctuation, so I put that option on the back shelf in favor of a certain run time. I am not actually sure of the critical temp of the pump head (and associated steel pipe), but I am certain that if I run much longer than 30 min., the temp begins to climb, and I know of no reason to run longer than that, so I guess I'm grasping at that certainty first.

Since my start switch is pressure/diaphragm activated, I do not have the luxury of breaking a low voltage/low current coil control, so it looks like I'm stuck with finding a relay that can handle 10A or so. Breaking one leg of 220 VAC is not optimal, but it would certainly stop the motor, so a 115 VAC relay is not out of the question.

I realize some have questioned the integrity of the PE switch itself, but I can assure all that it has been checked/replaced/adjusted, you name it, in my 15 years of fighting the problem. I have learned that Mother Nature can do strange things to the best laid plans. The biggest of which is frozen, or partially frozen, pipes. I solved the running out of water problem with a low pressure switch, thinking that if the input line to the pump from the storage tank froze (as it did a few times), then if pressure dropped below 20 lbs, it would kick. That worked nicely until the next winter when a small elbow coming out of the well shack before it dived underground froze. One would think that if the output line of the pump is closed shut with ice, then the pump would simply keep raising the pressure until the high side pressure switch cut it out at 60 lbs. When I realized there was a problem, I went down to the shack and noticed that the pressure gauge showed 52 lbs. Why?????....I don't know. Maybe a partially frozen pipe allowing just enough flow to keep it below 60 lbs. At any rate, it allowed to the pump to continue running, thus melting the pipe again.

This winter heat tape was applied to all possible pipes, and I thought for sure, I finally had it licked. Then on a mild day 3 weeks ago, I found the pump again running at slightly lower than the cutoff pressure. My only explanation is perhaps a cluster of air bubbles causing enough cavitation on the impeller to restrict pressure. Believe me, after all this time fighting causes, you finally resort to what you know will work. Just shut the damn thing off, if it runs over 30 min.

I'm afraid that's where I am at this tired point, and I do appreciate the suggestions.