Momentary Control of Motors, etc?


(Lester Ramey) #1

I have an application where I’m using 12 each Z-Wave switches that have normally open isolated contacts for controlling relays. The relays control motors, and other moving devices and can be controlled remotely through the Internet. The system works well, but I have the fear that in the event I’m a hundred miles away and the Internet were to stop responding, and if one or more of the motors were to continue to run; this would be very disastrous, and potentially dangerous. I’m currently using the Remotec model ZFM-80US. Any ideas on how to locally switch the relay on for a short period, maybe 5-7 seconds (or so), then it would automatically disengage. Remotely, turn it on again for another 5 seconds, and it would disengage, etc.

Since all the relays are in the same enclosure, I could fabricate a circuit board where each activation has a selectable time limit and then it would automatically disengage.

Any ideas would be appreciated.


(Paul Haskins) #2

From what I learned trying to something similar, ST does not work well with less than a minute. I was trying to do an interval timer.

I never tried with webcore and maybe it does better.

I have one that is supposed to turn a siren on for 10 seconds then off, sometimes it’s on for 5, ,some 12 or more. Never 10.

I’m sure others will chime in.


(MarkTr) #3

If there isn’t a good ST solution, what about replacing the relays with off-delay timer relays? Probably not a cheap solution but depending on the criticality of the operation might be worth it to you.

These are the ones I’m using in a project at work - they run about $70 each.


(MarkTr) #4

On the ST side, are the switches using a stock DH (locally processing)? If so, Smart Lighting runs locally, so maybe you could set up rules with Power Allowance to do the auto-shutoff.


#5

That device already has a built-in failsafe feature which allows you to have it turn itself off if it has not received an instruction from a specific Z wave device after a specified period of time. That’s how a number of community members have it set up for potentially dangerous runon use cases. This will work even if your hub dies all together, as it’s running in the firmware of the relay itself.

So I would just use that. :sunglasses:

@mike_maxwell uses this feature, I don’t remember if @johnconstantelo does or not.


(Lester Ramey) #6

Wow! I had no idea the answer was right under my nose, …so to speak. Thanks so much.!! I’ll give this a try.


(Lester Ramey) #7

It looks like the time for disconnect is in minutes. (up to 120). Do you know of a switch or a way of having the switch drop out after 20-30 seconds?