[ozzie34231]

I have some solid state relays, 5V to 115V that I want to use with a Mach 3 setup. One of them will operate an air solenoid that controls a spindle brake.
I've read that there could be a problem when the coil is turned off, (harmful back voltage ????)?
Please advise any simple way to avoid problems.
I'm electronically impaired, so please be explicit.
Thanks,
Ozzie

[underthetire]

Shouldn't be an issue with solid state. It's usually a problem with the dry contact relays. That's why I buy those with the built in led indicator light. Acts like a diode suppressor.

[Al_The_Man]

For AC inductive devices, use an RC snubber (search here for snubber) , for DC a Diode such as the 1N4000 series.
The coil or inductance in each produces a BEMF spike that can cause noise problems.
See post #2. http://www.cnczone.com/forums/genera...ion_error.html
http://www.electronics-project-design.com/diodes.html
Al.

[bobsch]

Don't worry about it. Solid state relays don't have a coil so there's no possibility of any inductive kick.

[Al_The_Man]

Don't worry about it. Solid state relays don't have a coil so there's no possibility of any inductive kick.

I think he is referring to the (inductive) devices they are switching?
Al.

[underthetire]

Still solid state. No arc.

[Al_The_Man]

There is BEMF across the coil of an inductive device at switch off.
Look at any Manufacturer engineering notes that will show when any SS device switches an inductive load there will be Overvoltage transients, the faster the switch, the higher the transient.
Some SSR's have a clamp diode or other across the switching device but it is always best to play safe.

http://www.crydom.com/en/Tech/Tips/D...guidelines.pdf

see last paragraph. http://www.crydom.com/en/Tech/Newsle...20an%20SSR.pdf

Al.

[bobsch]

There is BEMF across the coil of an inductive device at switch off.
Look at any Manufacturer engineering notes that will show when any SS device switches an inductive load there will be Overvoltage transients, the faster the switch, the higher the transient.
Some SSR's have a clamp diode or other across the switching device but it is always best to play safe.

http://www.crydom.com/en/Tech/Tips/D...guidelines.pdf

see last paragraph. http://www.crydom.com/en/Tech/Newsle...20an%20SSR.pdf

Al.

Good points. I was thinking of the input, not the output side of the relay. Thanks for the tips from Crydom, too.

[asuratman]

Do you mean like this attached. If you use PMDX 126, there is in manual about using it.