Film-Tech Forum ARCHIVE: "Delay Off" relay for exhaust fan

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Posted by Barry Floyd (Member # 385) on 06-30-2013, 09:54 PM:

I'm trying to select a latching relay that can be triggered by our American Cinema Equipment KLA-1 automation panel to engage the exhaust fan at the beginning of the night and insert that function into the start up cue for our projectors. I'd like that relay to be a "DELAY OFF" relay that can be triggered by the automation panel at the end of the night via the projector shut-down cue, and then have that relay hold the contactor for the exhaust fan on the ON position for 15 minutes then turn itself off.

I bought a Schneider Electric 211ACPSRX-6440 OFF DELAY relay, but either I can't figure out the wiring diagram on it, or it's not made to do what I want it to do.

Any suggestions. My control boxes on the wall are set up to use relays with a coil volt rating of 24 volts, and the contactor for the fan has a coil volt rating of 120 volts.

Any suggestions.

Posted by Jim Cassedy (Member # 4115) on 07-01-2013, 12:36 AM:

I built a system to delay the shut down of a roof exhaust fan 20min after
the projector shut down using a time delay relay similar to the one you specify.

I could not find a diagram for your relay online, but from looking at a stock
catalog photo of the product with a fuzzy wiring diagram on the side, the relay
you have should do what you want.

But - - here's what I think might be confusing you:
> The relay coil (& delay electronics) need 24V supply AT ALL TIMES
> The turn on and and delay sequence is initiated by the "switch" input
at the top of the relay diagram.

So what you really need from your automation interface is a dry contact
closure to turn the delay-relay (and thus your fan contactor) on & off.

I could probably give you a better answer ir I had a clearer image of the
wiring diagram on the relay.

But, as I said- - I used a similar relay to do exactly the same thing.

In the system I built the constant 24volts to ther relay was provided by
a seperate "wall wart" type powr supply that was on a circuit that was
never turned off.

Also, I used the 2nd set of contacts on the time delay relay to disable the
rectifier AC power contactor in case the relay or its' power supply failed,
making the exhaust fan inoperable.

Posted by Barry Floyd (Member # 385) on 07-01-2013, 01:19 AM:

Thanks for the input Jim. I think your right about the constant 24 volts. My field lights use a similar relay/contactor setup with a 24 volt transformer, all mounted inside the same wall mount cabinet. Only thing is that it uses a different relay.

I know my automation can "pulse" the contacts, but I'm not sure if it can HOLD the relay on.

I might have to use a separate latching relay like the one I used on the field lights to control the 24 volts going to the Delay Off relay.

Posted by Carsten Kurz (Member # 5396) on 07-01-2013, 03:07 AM:

Have you talked to an electrician? A very common device in europe is a fan-relay for bathroom ventilation fans. They switch on with the light and then run for a configurable amount of time after the light has been shut off. Very common in D.I.Y stores here.

Industrial timing relays are another option, but as mentioned, they usually need a separate 12V oder 24V AC or DC supply.

- Carsten

Posted by Louis Bornwasser (Member # 3063) on 07-01-2013, 07:24 AM:

For 45 years I have used a device that mounts in a single gang box that is an egg timer with a switch on the back. When you leave, you set it to 60 minutes and turn the regular switch off. You mount this in a 2 gang box along with the regular switch.

Posted by Dave Macaulay (Member # 813) on 07-01-2013, 07:41 AM:

You want to be sure the fan goes on, so you require two pulsed automation outputs, ON and OFF. I don't know this KLA-1 so no idea if that's possible. Some automations have a "slide projector" relay that is closed except when the show is on: this can be inverted (with another relay or by rewiring the existing one) and used for exhaust control.
Once you manage to automate the fan on and off, it's easy to get a delayed off - just use a delayed off relay in the power circuit of the fan. Connect the coil to your fan power, and switch the fan through the contacts. A Dayton 5WMK0 would do.
The relay you bought is discontinued and I can't find any data on it.
If your KLA-1 is an old single projector 35mm automation, I suggest scrapping it and using a modern network automation controller like the ECNA or Jnior. These are very flexible. With a Jnior I believe you can add an off delay function using the "cinema Jnior" application, probably even monitor the lamp status and operate the fan as required.

Posted by Barry Floyd (Member # 385) on 07-01-2013, 08:53 AM:

Louis... I already have the exact same "egg timer" scenario you describe. We have a 3 gang box in the wall, with 1 gang being a "manual override ON" switch for the field lights, the other two gangs have a simple on-off switch with pilot light for the exhaust fan, and a 30 minute Intermatic spring driven mechanical "egg timer". The way it's set up now, we manually flip the exhaust fan on via the switch/pilot light. At the end of the night, I can twist the timer around to the 15 minute mark, flip the switch to the off position, and the fan will shut off after 15 minutes when the "egg timer" lets it go. The egg timer works perfect to shut the fan off. What I'm looking for is a way to automate the fan so it turns on with the projector start up cue, runs for the duration of the shows for the evening, then turns off 15 minutes after the projector shut down cue.

Dave... the KLA-1 panel is a brand new IMB GPIO automation panel that was manufactured by Kimber Labs for American Cinema Equipment. I'm thinking I'm gonna need to get another "latching relay" to control the switching of the delay off relay. Pulse "on" and latch to engage the contactor and start the exhaust fan, then pulse again "off" to disengage the latching relay which would in turn start the delay off sequence on the other relay.

We were able to get the "delay off" relay to work last night, and like Jim Cassedy said, I just need a dry contact closure to turn on the relay and to initiate the delay-off sequence.

Posted by Brandon Boutte (Member # 7843) on 09-03-2013, 08:17 AM:

You can use an SSAC relay. They are very inexpensive. ABB used to own them. Now SymCom owns it.

Posted by Barry Floyd (Member # 385) on 09-03-2013, 02:03 PM:

I ended up going with the Schneider Electric 211ACPSRX-6440 OFF DELAY like in the first post above, but I was wiring it up wrong.

Finally figured out I needed the automation panel to trigger a "latching relay" that will hold the contactor coil throughout the time I want the exhaust fan to run, and then have the automation panel trigger the latching relay "off". When the latching relay is released, it then starts the 15 minute delay of the other relay. Have had both booths converted to this for about two months now, and it works flawlessly. Never have to worry about someone (me) forgetting to turn the exhaust fans on or off.