I usually use Opto22 make, they have built in snubbers and zero switching on/off.
Max.

i saw those, Mouser didnt have them. the Omron has built-in varistor but spec sheet doesnt really say what its ratings are. i'll add two (parallel) of the Little Fuse items.

leakage current is about 7mA for both Omron and Opto22. that's 0.84W of power leaking when SSR is off. anything to be worried about?

 

leakage current is about 7mA for both Omron and Opto22. that's 0.84W of power leaking when SSR is off. anything to be worried about?

Normally on a low inductance - high current load it is not a problem.
Max.

 

i am into this design as follows. havent chosen R1 value yet (maybe 500). any concerns with it? the K1 coil is rated 24v @ 15mA, this being sinked by a dip IC (S1 in this pic, SSR would be adding 7mA to that (~50% more amps), you think the IC can handle 22mA? stupid IC on the board has no markings, looks like it may have been epoxied over in black, or the maker was too cheap to silk screen or laser the chip info onto the package.

 

What do you need R1/R2 for, most SSR's have inputs already conditioned?
What is the input rating of the Omron?
Max.

 

What do you need R1/R2 for, most SSR's have inputs already conditioned?
What is the input rating of the Omron?
Max.

opto is "rated" 5-24, and "operating" 4-32" Vdc, 7mA(max)

R1 also can act as a current limiter if the opto decides to short. thus protecting the unknowns of the control board. i am not sure yet what the Vdc is, i see resitstors in series with the relay coils which leads me to believe the Vdc is higher than coil ratings, but its probably 24Vdc.

another Q is this, on PS2, should PS2 B be mains hot thus keeping mains hot off of the motor when the SSR is off? i updated post #43, the MOV's will go across the motor because the SSR has internal MOV (per the Omron app guide).

 

I think you are over engineering things. If the SSR is rated for 4 - 32 VDC on its control side adding resistors and what not is totally pointless. If It was me I would just disconnect the old relay and feed its coil power directly to the SSR and be done with it.

Now as far as an SSR burning down I have never seen one take out its control side. It's the power side that goes out usually either in a dead short and staying on all the time or burning a hole in the case where the switching devices are located ending in an open circuit.

Snubber wise with induction motors and SSR's there is no such ting as too many or too big and I would be inclined to also add one or more across the motor leads as well.

 

I think you are over engineering things. If the SSR is rated for 4 - 32 VDC on its control side adding resistors and what not is totally pointless. If It was me I would just disconnect the old relay and feed its coil power directly to the SSR and be done with it.

Now as far as an SSR burning down I have never seen one take out its control side. It's the power side that goes out usually either in a dead short and staying on all the time or burning a hole in the case where the switching devices are located ending in an open circuit.

Snubber wise with induction motors and SSR's there is no such ting as too many or too big and I would be inclined to also add one or more across the motor leads as well.

its just 5 parts total, and extra resistor here or there is not a big deal though..... and recall, the control for the SSR is an unknown dip IC that will sink to gnd.

i want to leave the relay for now, it actually switches over to the NO side to power the M.Hi speed of the motor when in heat mode. i am still looking at if my system really needs two speeds, and if not what speed would be best, Hi or M.Hi.

the Omron is rated 5-24v, operating 4-32. not really sure what the diff is there, but i suspect its 4min and 32max and 5-24v is the safe range.

the MOV's will be across the motor since the Omron has a MOV in it already.

 

here's an update, ran the fan motor on all 4 speeds directly to mains power. with these results i suspect that me fixing the bad wiring caused the relay pins to melt off. before the fix the inrush was 30A and running was ~14+ (hi speed).

direct to mains i measure this:

Inrush...and...Running​

Hi 32.3...........13.3
M.Hi 19.3..............8
M.Lo 12.8..............6.7
Lo 9.3...............5.9


i just cant understand why the maker thinks it was ok to use a 10A relay to run Hi speed.

my SSR setup will fix it, but i am planning to run heating and cooling on the M.Hi speed, but will do some CFM testing to make things are good.

 

update,
since the hvac is tuned to run heat and cool at different speeds i will modify the board so that the relays will switch the Vdc (and not the 120Vac), this then allows me to control the SSR's directly. here's what it looks like:

S1 feeds power to S2 for all fan speeds (on/off), and S2 switches between cool or heat (NC for cool, and NO for heat).

 

just an update, i like to show things from problem to fixed. got all my parts in. here's the Omron on heatsink. drilled and tapped new holes so the sink can take on another SSR since my HVAC runs the motor at 2 speeds using different windings. and the dual MOVs per motor coil (common gnd). i will epoxy encapsulate these MOV's into a small AL case that is approx 3x2x1 in size.

 

installed it all, works just fine. need to order a 2nd SSR and hook up the other motor winding.

 

Good deal!
Just reroute a few wires and put a dozen or so more zip ties in place so it doesn't look like a contractor did the work and you're good to go!

 

Good deal!
Just reroute a few wires and put a dozen or so more zip ties in place so it doesn't look like a contractor did the work and you're good to go!

yeah, i need to go back in there to fix a wire and to add another SSR, and will clean it up.