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Topic: Time delay relay for a fan

Brandon Boutte
Film Handler

Posts: 2
From: Seattle, WA, USA
Registered: Aug 2013

posted 02-15-2019 04:36 PM

I built a system to delay the shut down of a roof exhaust fan 10 minutes after the projector shut down using a time delay relay . https://www.valinonline.com/products/tdb24dl Either I cannot figure out the wiring diagram on it, or it's not made to do what I want it to do.

Any suggestions would be greatly appreciated.

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Arnold Chase
Film Handler

Posts: 41
From: West Hartford, CT United States
Registered: Nov 2013

posted 02-16-2019 02:00 AM

What you want is a classic "off-delay" setup. The key is that you need to find a 24 volt DC projector output that goes on and off with the projector fan(s). If you feed that to the relay control input (S1), then the TD relay trigger input will properly start the delay cycle. If you supply the delay relay power input with the same power that's feeding the fan(s), it will not work. The TD relay power input needs to be connected to an always-on power source.

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Dave Macaulay
Film God

Posts: 2321
From: Toronto, Canada
Registered: Apr 2001

posted 02-18-2019 04:22 PM

That is an odd choice for a fan delay relay but it will work.
To make it work you need a 24vdc supply to it all the time, and a "fan on" switch that switches the 24vdc to the initiate terminal. The delay starts when you switch off.
Usually we use a 120vac delay relay that works the same... saves providing the 24vdc.
This would be good if you use gpo triggered by lamp on to automate the exhaust fan though, the gpo can switch 24vdc safely.

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Carsten Kurz
Film God

Posts: 4340
From: Cologne, NRW, Germany
Registered: Aug 2009

posted 02-18-2019 04:50 PM

Also an expensive choice. There are commodity mains supply delayed-off relays available for bathroom fans, staircase lighting etc. that can be bought for a fraction of that price.

- Carsten

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Barry Floyd
Phenomenal Film Handler

Posts: 1079
From: Lebanon, Tennessee, USA
Registered: Mar 2000

posted 02-18-2019 07:57 PM

I built our system here at the drive-in that do exactly what you describe you want to do.

Ours is set up to be triggered "ON" as soon as the playlist starts. At the end of the playlist, I have another cue which triggers the "Delay OFF" relay. Our Delay off relay can run up to 15 minutes after the playlist ends and shuts off the exhaust fans.

I used a "Schneider Electric TIME DELAY RELAY 211ACPSRX-6440. 24V AC/DC OFF DELAY"

I also have a 15 minute "Intermatic" spring wound mechanical timer wired into the same circuit that does the same thing IF our other one ever craps out on us.

Shoot me a private message with an email address, and I'll send you a PDF of the wiring schematic of how ours is done.

Have a look at this thread from several years ago...
Exhaust Fan Delay OFF Relay

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