I have a motor with control switches near it. Using this setup no problem.
Also use a remote switching system (100 feet of wire) using 24v to switch a
relay near the motor to control it.. This causes a loud thump in the nearby
audio system on break. Must be acting as an antenna. Resistor/capacitor
across the relay contacts does nothing.
Any ideas?

"genev" wrote ...
I have a motor with control switches near it. Using
this setup no problem. Also use a remote switching
system (100 feet of wire) using 24v to switch a relay
near the motor to control it.. This causes a loud thump
in the nearby audio system on break. Must be acting
as an antenna. Resistor/capacitor across the relay
contacts does nothing. Any ideas?

Snubbing the relay contacts is a good idea anyway (to
protect the contacts). But sounds like you also need to
snub the relay coil and/or remote switch.

Is the low control voltage AC or DC?
If it is DC, a backwards diode across the coil will
absorb the current spike from the collapse of the
magnetic field when you turn it off. This is a very
common solution to the turn-off problem.
If it is AC, a similar resistor/capacitor snubbing
circuit across the remote switch may be in order.

Is the remote switch wiring twisted and/or shielded?
It is also possible that the wire is acting as a
transmitting antenna for the turn-off spike.

The cable is a twisted pair, and not easily replaced. The control voltage
is 24 VAC. Additional snubbers are a good idea and I'll try that. I also
thought that perhaps changing to a TRIAC would help, but would have to check
if they can take the motor's inductive load. Shielding the cable and/or
somehow isolating the remote circuit from the load may be necessary here.
I'll try your suggestions, and post my results. And of course, any
additional thoughts would be very welcomed.

The control wire is twisted pair, and not easily changed. The control
voltage is 24 VAC. I will try additional snubbers on the coil and see how
that works. I would consider changing to TRIACS, but would have to check to
see if they are rated for a motor's inductive load. I'll post any new
results. Also, any additonal thoughts would be greatly welcomed.

"genev" wrote in message
news:Cx5lf.16465$Mi5.14806@dukeread07...
I have a motor with control switches near it. Using this setup no problem.
Also use a remote switching system (100 feet of wire) using 24v to switch a
relay near the motor to control it.. This causes a loud thump in the nearby
audio system on break. Must be acting as an antenna. Resistor/capacitor
across the relay contacts does nothing.
Any ideas?

"genev" wrote ...
The control wire is twisted pair, and not easily changed. The control
voltage is 24 VAC. I will try additional snubbers on the coil and see how
that works. I would consider changing to TRIACS, but would have to check
to see if they are rated for a motor's inductive load. I'll post any new
results. Also, any additonal thoughts would be greatly welcomed.

If the control voltage is AC, it might be better to put the snubber
across the switch at the remote location, but I would try both
at the switch and at the coil.

Ok, will try it and see.
thanks for the help.

Richard


"Richard Crowley" wrote in message
...
"genev" wrote ...
The control wire is twisted pair, and not easily changed. The control
voltage is 24 VAC. I will try additional snubbers on the coil and see
how that works. I would consider changing to TRIACS, but would have to
check to see if they are rated for a motor's inductive load. I'll post
any new results. Also, any additonal thoughts would be greatly welcomed.

If the control voltage is AC, it might be better to put the snubber
across the switch at the remote location, but I would try both
at the switch and at the coil.