Really simple AC relay options? To just open and close a switch 1

[artcorp]

I have what I thought was a simple project:
Install an hour-meter (Hobbs meter) into our ultraviolet curing oven. The meter will allow us to know when the bulbs should be replaced (every 500 hours).

I have a Redington counter (5300-0000).
The meter counts when a jumper is attached between pin #2 and pin #3.

The trouble is that I have no means to wire the meter into the UV chamber since every contact I have found is under line voltage.
What I think I need is a relay that just has four simple contacts.
Contacts 1 and 2 will accept line voltage (120V) that will open and close a relay.
Contacts #3 and #4 will be wired to the meter. The contacts should normally be open (so the meter does not count. Then, once power is applied to the relay the contacts will close and the meter will begin counting. The meter in this case should not receive any voltage from its connections, I just need to effectively open and close a switch between two pins.

Space it not really an issue in the machine as there is plenty of room available. Something tells me that this should be a simple controller but I am not familiar with anything that would accomplish this.

I know that hour meter are available that will count when AC or DC voltage is applied to them, but I'm trying to work with what we have available.

Thanks!

 

[IRstuff]

So what's the problem?

Digikey lists over 60 relays that run off 120VAC

TTFN

 

[VEBill]

That counter is just a 'Totalizer'. Connected as you've described, it would just count how many times the oven has been used (not how many hours).

Suggestion: Purchase a suitable Hour Meter ($10?) and simply wire it up in parallel with the switched AC that eventually leads to the bulb-in-question.

 

[ScottI2R]

Artcorp,
Yes, what you think you need is correct. However, I believe what you refer to as contacts 1 and 2 to turn on the relay would actually be connected to to the 120V coil of the relay. THIS would turn on the relay and close the contacts effectivly jumpering pins 2 and 3 of your hour meter. Just parallel the relay coil off of something that runs while the lamps are on.

Hope this helps,
Scott

In a hundred years, it isn't going to matter anyway.

 

[ScottI2R]

oooo! Good catch on that one VE1Bll!

Scott

In a hundred years, it isn't going to matter anyway.

 

[VEBill]

Is the oven on for a fixed duration each time so that you could convert the counted 'On Events' into 'Hours'?

 

[artcorp]

Thanks for the amazingly fast replies so far!

Good catch on the timer vs. totalizer. I typed in the wrong part number. I actually have a 5320-000.
The oven does run for a fixed time (30 minutes) each time. So a totalizer would work if needed.

I've found where I want to tap into the AC lines and I'll put the relay inline with the motor that spins the internal turntable (sort of like in a microwave oven so the parts get "cooked" evenly). The motor only runs when the lamps are lit.

Digikey looks like they will more than likely have a relay that I can use. If I had known of that site I may have taken a look there before posting, thank you for suggesting it.

ScottI2R, that is exactly how I need to set this up.

My questions after looking at the Digikey site are:
What is the type of relay I am looking for called? There are 15+ sub headings under "relays". I'm guessing that "General purpose" relay would work?
This relay should not need a contact rating since it is not passing any current and is just operating a switch... right?
Am I looking for a SPST-NO switch function? I just need it to be Normally Open, and a SPST would seem to suit my needs.

Regards,

 

[itsmoked]

Why bother with a kludgy relay and socket and wiring and logic errors? You have to buy something, buy the right thing, an AC hour meter!

Get the correct hour meter.. hook up two wires and you are done!!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[itsmoked]

Pick one.

http://www.alliedelec.com/Search/SearchResults.asp?SearchQuery=hour meter&source=google

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottI2R]

Artcorp,
Whoa for a sec! DO NOT wire the relay "inline" with the turntable motor lines. This would cause motor drive current to pass thru the coil of the relay which will not like it and burn open, stopping your motor and your hour meter! By "inline" I mean in series, where you would break one of the motor lines and goto one terminal of the relay and then off the other terminal to the motor. That would be a bad thing. The way to do it is to find the connection where the motor gets its power and simply run the two wires from that point to the relay coil.

Good luck

Scott

In a hundred years, it isn't going to matter anyway.

 

[ScottI2R]

Forgot something. An SPST would work fine. Unless you would like additional contacts for "future" enhancements. The price diff is nill....
And YES. Go N/O on the contacts. Most GP relays that aren't automotive have sets of N/O as well as N/C.

Scott

In a hundred years, it isn't going to matter anyway.

 

[IRstuff]

yes, general purpose:

http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=368514&Site=US&Cat=35128104,

Select the 120VAC and 3A. Digikey doesn't stock anything with less than 3A capacity.

TTFN

 

[ScottI2R]

Smoked DOES have a point.

In a hundred years, it isn't going to matter anyway.

 

[itsmoked]

Yeah I'm laughing at the complexity of all the descriptions, even the describers are confusing the descriptions!

I am also not shooting 'from the hip' here.. I have gone down the stoopid kluge method "to save a buck" many times.

Always looked back and thought, "Gesh what a kludge, I'll never do that again!"

Heck, I have a truck that has an air shifter in it. I have parallel air compressors to charge an air tank. The automatic air pressure switch doesn't shut off the power via a 12VDC self-latching relay (kludge) correctly. I have to listen for a strange clicking noise while speeding down the freeway. When I hear it, I have to turn off the truck's ignition and then turn it back on, always hoping the steering doesn't lock.

artcorp's mission would make sense if proper hour meters were $200. But when they are just about the price of the relays not counting the 2-3 hours it will inevitably take to complete the 'relay exercise' it doe-na make no sense to me.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottI2R]

Smoked,
Give me an unlimited budget, (or at least a really juicy expense account) and I will over complicate someting to the ludicrous level! How much would you like to pay for my new and improved Mouse Trap! It includes a guillatine sharp, poison coated (pet safe of course), inconel decapitating snapper! It dices, it slices, it even makes julienne .....hmmm mouse! Every household should have one!

Love this forum!!!

Scott

In a hundred years, it isn't going to matter anyway.

 

[IRstuff]

Not quite that cheap at Digikey, but close enough to junk the relay idea:

http://www.digikey.com/scripts/DkSearch/dksus.dll?Criteria?Ref=394558&Site=US&Cat=35783490

Note the last column and the choice for line voltage operation, which results in two meters from Curtis Instruments, both costing less than $25

TTFN

 

[machmech]

Nice advice and a good link Keith, We have a similar application our bulbs cure cyrel photopolymer flexographic printing plates even exposure is critical for proper rise and durometer of plate material. If the bulbs get weak we lose image quality.

Chuck

Getting older is inevitable
Acting your age is optional

 

[OperaHouse]

Maybe just change the switch to one with double set of contacts, one set for the lamp and another for the timer. Don't forgrt there are GO-NO GO self powered current sense relays. Loop a couple turns of wire through the current transformer and the unit is self powered with a set of NC NO dry contacts. One such unit is the MCDR-10 manufactured by

http://www.rke.com