Anti kickback diode on SSR?

SolarMusher · August 2015

I would like to start a two wires propane generator on aux SOC from a classic using a crydom ssr relay. I've read that some people advise to protect the controller from inductive kickbacks.
Do I really need to mount an anti kickback diode on this ssr when I just need to switch a small voltage signal from the gen to start it?
Erik

waynefromnscanada · August 2015

The SSR input and output should be totally electrically isolated from each other via opto coupler, thus preventing any "kickbacks" getting into the charge controller. Lightening of course will ignore any isolation, as it would any diodes you might add. Check the specs of the SSR you plan on using, just to confirm.
If the output of the SSR is powering a DC magnetic relay or DC solenoid though, there should be a damping diode across the coils involved though, to prevent spikes damaging the output circuit contained within the SSR.

boB · August 2015

It is the SSR's load side you need to protect from the (typical) inductive load characteristics of the DC load being switched by that SSR.

....Unless it is an AC load, in which case it doesn't (typically) matter.

And, an SSR doesn't normally have an internal relay coil.

boB

SolarMusher · August 2015

boB wrote: »

It is the SSR's load side you need to protect from the (typical) inductive load characteristics of the DC load being switched by that SSR.

....Unless it is an AC load, in which case it doesn't (typically) matter.

And, an SSR doesn't normally have an internal relay coil.

boB

Hey boB,
If I read this Kohler diagram correctly (14res), remote start wiring (P1-8 and P1-20) seem to be already diode protected.
Wayne, this SSR is a Crydom D1D20 (DC in, DC out), it only switches remote start leads.

Attachment not found.

boB · August 2015

Oh, just a generator start. Relay coil, huh ? Hmmmm...

Well, a clamp diode might be a good idea but it may very well be in there already like you say.

boB

SolarMusher · August 2015

boB wrote: »

Oh, just a generator start. Relay coil, huh ? Hmmmm...

Well, a clamp diode might be a good idea but it may very well be in there already like you say.

boB

boB, where would you add this clamp diode? across the solenoid?
Oh, and could Aux1 (SOC low) drive two ssr? One which would control a 120Vac gen heater and another Dc one (with timer) which would start the gen after a delay?
Thanks,
Erik

boB · September 2015

SolarMusher wrote: »

boB, where would you add this clamp diode? across the solenoid?

Erik

Across the coil that is being driven from the Classic's Aux output.

So, you want to point the diode polarity so that it "catches" the voltage spikes as
the coil power disengages. Let's see.....

Sorta like this. Hope it comes out. Need Courier font.

This did NOT look correct when I viewed it after posting. Dang. Copy it and paste
into a word document or something using Courier or Courier new non proportional font.
Nope ! That didn't work for me either !

OK, anyway, anode of the diode to the negative side of the coil.
Cathode at the positive end of coil.

boB

AUX OUT DIODE COIL

| | |
/+\ | |
( ) - C|
\-/ ^ C|
| | C|
| | |
| | |
| | |
|

|

|

(created by AACircuit)

SolarMusher · September 2015

boB wrote: »

Across the coil that is being driven from the Classic's Aux output.

So, you want to point the diode polarity so that it "catches" the voltage spikes as
the coil power disengages. Let's see.....

Sorta like this. Hope it comes out. Need Courier font.

This did NOT look correct when I viewed it after posting. Dang. Copy it and paste
into a word document or something using Courier or Courier new non proportional font.
Nope ! That didn't work for me either !

OK, anyway, anode of the diode to the negative side of the coil.
Cathode at the positive end of coil.

boB

AUX OUT DIODE COIL

| | |
/+\ | |
( ) - C|
\-/ ^ C|
| | C|
| | |
| | |
| | |
|
|
|

(created by AACircuit)

Thanks boB, I will follow your advice!
Erik

Anti kickback diode on SSR?

Comments