Manual Reset Relay problem

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dewdiehl

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Louisville, KY
We have a comercial kitchen with a Ansul sytem connected to a electric gas valve with a manual reset relay. We have installed a backup generator to keep the kitchen and other areas of the building powered up durring a power loss.

Our problem now is that everytime the power goes out and or the auto transfer switch transfers the manual resest relay trips and turns off the gas. This causes the kitchen pilots to need relit several times for evey power outage.

I have installed a UPS to power the gas valve and relay. The problem I'm having is the UPS dosn't always tranfer quickly enough for the relay. This is a very good UPS providing pure signwave output.

If I could just make the realay delay for 1 second I think the problem would go away. I would appreciate any suggestions. Thanks in advance!
 
If the UPS cannot handle this you have another issue IMO. Check the control wiring. Are you using a relay with powered during transfer?
 
Why not change the relay to a normally energized off delay,time open and set the time to delay opening to what ever gives you the necessary ride thru that you desire.?

dick
 
Thank you for the responses.

The valve is a long way from the Ansul system so a cable is out.

brian john said:
If the UPS cannot handle this you have another issue IMO. Check the control wiring. Are you using a relay with powered during transfer?
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I don't understand? I'm powering the main supply power to the relay that powers the gas valve.

Changing the relay concerns me as to safety. I believe the reason for the current setup is so that when there is a power loss and the valve closes that it won't reopen without someone knowing and filling the kitchen with gas. I'm using the UPS so the power doesn't go out but what if the UPS fails. I would like the valve to fail closed in any event something goes wrong.

Should this very simple relay be this sensitive to a power loss when I'm using a UPS capable of network and file server use? Is there a way I could add a capacitor, etc to the supply side of the relay to give me just a little more time?

I really do appreciate the help!
DeWayne
 
Is the ups supplying only the relay? If so that is probally why it still drops the gas valve. The coil on the valve should also be supplied by the ups, due to the valve temporarily closing during the power loss cutting the gas flow.
 
Are you talking about the Honeywell type Ansul reset relay?

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dewdiehl said:
I have installed a UPS to power the gas valve and relay. The problem I'm having is the UPS dosn't always tranfer quickly enough for the relay. This is a very good UPS providing pure signwave output.
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As DeWayne has suggested, this cant possibly be the case; any half-decent non-on-line UPS will have transferred to battery in less than a cycle, and no relay you are likely to be using will drop out in 1/60th of a second. An on-line UPS (these are the "very good" type) will have no output drop at all through the transition.

This leads me to wonder just this arrangement is wired, as my suspicions are wiring error. In particular, perhaps the UPS is not supplying all the elements necessary to prevent the gas valve from being closed...?
 
dbuckley said:
This leads me to wonder just this arrangement is wired, as my suspicions are wiring error.
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I suspect this also, which is why I posted a picture of the relay I think he's using. If that's the relay, I think I know the problem already.
 
Yes the relay pictured is what is attached to the valve except it is older and made by DET Tronics PN#14702. The UPS is a switching type not constant (APC SmartUps750).

As for wireing. Sometimes it will work just fine and others it won't. I would think if it were a wireing issue that it would fail everytime. I will take another look at it though and make sure.

I'm a little confused by some of the comments. Is that type of relay more sensitive to electrical interuption then a switching UPS can provide.

Thanks again for all the great help!!
 
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Do you know the tranfer switching time of your UPS?
I took a quick look and they are not very good about making it obvious.
I found some switching times of up to 8 -10ms (but not sure they match your particular UPS).

That could be enough for a relay to drop out. It is probably right on the edge of the relay drop out time and thus intermittent.

If you do not want to change the relay then possibly a small dc power supply to small inverter), or a better on-line UPS?

If you could change then using a small dc power supply with a DC coil would work.
 
Your right they don't publish the transfer times. I thought that if it were fast enough for computers and the like that it would be for this also. Maybe because computers use DC circuits their more tolerable to transfer times. Yes the easy answer would be a online UPS but there over $1,000.

I like the idea of a DC relay. Do they make such a thing with the transformer and reset button all together or is this something I would have to build myself?

Thanks for the ideas!
DeWayne
 
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