Air Compressor Timer

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  #1  
Old 09-28-07, 05:50 PM
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Air Compressor Timer

I forgot to turn off the circuit breaker to my air compressor last night. Well, during the night it turned on, and at some point both connecting rods broke. Since it couldn't build pressure, it ran for who knows how long until I heard it running this morning.

Is there a method or system available to prevent an air compressor running uncontrolled for long periods? I thought of using a timer that could be set to run for, say, 30 minutes every time the compressor starts and resets when the compressor turns off. I think that would be long enough since I don't believe I would ever need to operate the compressor any longer, but if it were unattended, short enough to prevent an uncontrolled run time.

I've searched online, but haven't found anything that has a delay longer than 17 minutes.

Any thoughts?

Thanks!

Larry
 
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Old 09-28-07, 06:29 PM
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A short search brought up this.
http://relays.tycoelectronics.com/time_delay.asp
Got to be something in there you could use.
 
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Old 09-28-07, 08:03 PM
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Why couldn't it build up pressure and shut off on its own?
 
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Old 09-28-07, 09:08 PM
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Not exactly sure if a timer is the way to go.

There is no reason for the compressor to start while not being used.
If the system was checked for leaks and they were repaired would never start.
A common place for pressure loss is a bad check valve.

As far as a timer goes the simplest type for this would be a spring wound type.
The kind that are commonly used as fan timers.
You might need a contactor for any timer you get unless it has a high enough amperage rating.
 
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Old 10-01-07, 11:10 AM
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A "Lock-out" circuit using relays is possible--- three relays are needed ---

(1) A "Compressor Run " ( "CR") relay with two Normally Open contacts and one Normally Closed contact.

(2) A "Compressor On" ( "CO" ) relay with two Normally Open contacts.

(3) A "Lock-out " ( "LO" ) relay with one normally closed contact.

Operating Sequence---

The "CR" relay is wired in series with the NC contact of the "LO" relay and the Normally Open contact of the Pressure Switch ("PS") . When the PS closes, the "CR" relay is energized ---- one "CR" NO contact closes the circuit to the compressor motor , and the other "CR" NO contact closes the circuit to the "CO" relay which operates .

One "CO" NO contact "shunts" the "CR" contact , and the "CO" relay is "locked" operated thu it's own NO contact.
The other "CO" NO contact is in series with the "LO" relay , and causes a partial closure to the "LO" relay circuit.



When the PS opens , the circuit to the "CR" relay is opened , and the "CR" relay releases. The NC contact of the "CR" relay completes the circuit to the "LO" relay thru the NO contact of the "CO" relay, operating the "LO" relay.

The "LO" relay remains operated thru the NO contact of the "locked-in" "CO" relay and the NC contact of the "CR" relay




When the "LO" relay operates, the NC contact of the "LO" relay opens the circuit to the "CR" relay , which leaves the circuit to the "CR" relay in a "locked-out" mode, preventing any further operation of the compressor.

A "manual" opertion is required to restore the operation-- this is a "Reset" push-button with a NC contact , the NC contact in series with the circuits to the "CO" and "LO" relays. When the Reset button is pushed , the "CO" and "LO" relays release, and the release of the "LO" relay will re-close the circuit to the PS.
 
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Old 10-01-07, 08:08 PM
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"I forgot to turn off the circuit breaker to my air compressor last night. Well, during the night it turned on, and at some point both connecting rods broke. Since it couldn't build pressure, it ran for who knows how long until I heard it running this morning."

Repair the compressor, and check the pressure switch , you should be OK.


PattBaa, Great suggestion. I now know another source for tough control issues (There are many of them).
 
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Old 10-02-07, 06:16 AM
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I agree with Lee, repair it, check for leaks and make sure the pressure switch operates properly. One problem with the timer, is that while you are working, it won't turn on if the time has expired, and you will be only partially driving nails, etc. I have done the same thing, so I installed a big red push button disconnect switch just above my light switch. As I leave the shop, I have to turn off the lights, and the red button reminds me to turn off the compressor. It is conditioning the user, not making it fool proof.
 
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Old 10-02-07, 05:27 PM
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A timer between the pressure switch and the compressor motor
will work.

Roger
 
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Old 10-02-07, 10:30 PM
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If the compressor is a small one or has a magnetic starter, a "spring wound timer" could be used, they come in 15,30,60 min. and 12 hour models, one would have to verify that they were rated for the load, if a mag starter was used, the timer would only control the load of the coil in the starter.

Intermatic is one manuf. of them.
 
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Old 10-03-07, 12:12 AM
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I could be wrong but this seems rather a simple deal. If I place a timer in series with the line/load to the compressor motor and I set that timer to open the circuit about 2 or 3 minutes after the pressure switch shuts off the motor at high pressure set. This would IMO be pretty straight forward....if the tank doesnt pressurize in the time it takes to reach normal high pressure and continues to run, the timer will shut it off. It will reset to zero time as the pressure switch cycles the compressor....ie... on call for pressure then switch off at high pressure limit ..timer resets to zero compressor cycles but if there is an air leak and it continues to run the timer shuts it off.
 
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Old 10-03-07, 12:37 AM
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Roger it can be done that way.

there are quite few ways to do this what Pattbaa have one idea

here is other idea is get the lighting circuit tied to the maganitc switch [ contractor for compressor ] that will active the relay as long the switch for lighting circuit is on the relay stay on the compressor can cycle by pressure switch until you turn off the light the relay will drop the coil circuit to prevent the compressor start up


this one of few idea i think few other may join in with this idea

Merci, Marc
 
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