Solid State Relay problem?

[WoodNotOil]

I am trying to control a grundfos 15-58 pump with this solid state relay http://magnecraft.thomasnet.com/ite...57?&plpver=10&origin=keyword&by=prod&filter=0 . The coil part of the relay is working fine from my Arduino controller board. When I test with my multimeter I am getting 110v through the output wire going to the pump. However, once I actually connect the wire to the pump I get nothing. The pump does not come on and the meter reads zero. Disconnect the wire and check it and 110v. Thinking it might be a problem with the the pump I connected it back to the aquastat that had been running it and it runs fine. What's going on here? I am confused. Is the pump unable to get enough amps to start? What is the remedy?

 

[DMX_512]

Just taking a guess here.
The Pump Motor might not like the switching rate or timing of the relay.
What is telling the contacts to close and trigger the pump on?

 

[maurice]

I really think it is the relay. Since it is a 3 amp output, the relay may not be strong enough to run the pump (the pump will have an inrush current amp draw above the run amp.) It is possible that the relay will output 110v w/o load, but when you connect the load, it completely cuts out. I've seen it happen on other stuff I've worked on. Do you have an amp-clamp meter? Or what is the amp reading on the pump label? If the pump is 3 amps when running, then get a stronger relay, perhaps 10 or 20 amp rated.

But if you want to check this stuff, you could rule out the pump: The pump should have 2 wires. One is the supply from that relay. The other will be neutral. Keep in mind you are checking voltage DIFFERENCE.

Check voltage AT the pump on those 2 wires. If you get 110 volt difference AT the pump and the pump is not running, you have a pump problem. (Might even be some crud stuck in the rotor, or the magic smoke may have escaped. But since it runs with a different control the pump is probably ok.)

If you do NOT have 110voltage difference at the pump, then: 1. check for voltage from that relay supply wire AT the pump to a good known neutral. Based on the voltage difference I mentioned, you could then check voltage at the output neutral of the pump to that good known neutral. If you still have 110volt then you have a broken neutral from the pump. BUT I THINK ALL THIS IS OK.

Does this help?

 

[WoodNotOil]

I really think it is the relay. Since it is a 3 amp output, the relay may not be strong enough to run the pump (the pump will have an inrush current amp draw above the run amp.) It is possible that the relay will output 110v w/o load, but when you connect the load, it completely cuts out. I've seen it happen on other stuff I've worked on. Do you have an amp-clamp meter? Or what is the amp reading on the pump label? If the pump is 3 amps when running, then get a stronger relay, perhaps 10 or 20 amp rated.

The cutting out is exactly what I am experiencing. I do not have an amp clamp meter. The pump only draws between .55-.75A and I tried it on low. I have checked the voltage every which way and it checks out so long as it is not actually connected to the pump. Then nothing. It will even light up my test light just fine (when not connected to the pump). The pump is back to working off the aquastat right now, so the problem is definitely not the pump. I assumed 3A would give me the buffer needed on start up, but maybe not. I suppose I will either need to replace it with a higher Amp relay or have it charge the coil of a second more robust relay. Anyone have any other thoughts or experience with this?

 

[maurice]

Motors can have 10 times the running amp current on start up depending on the load.

Yes, you definitely can have this small ss relay operate a bigger relay. Probably find a cheap new relay or contactor at an hvac supply or graingers, or similar (or salvage off of used equipment?). (Just make sure the coil voltage matches at 11v.)

 

[WoodNotOil]

I like this one http://www.allelectronics.com/make-a-store/item/RLY-453/120-VAC-RELAY-DPDT-12-AMPS/-/1.html can't beat the price for what it does. Thanks for the help.

 

[Tarmsolo60]

Put a 60 watt light bulb in for the relay load instead of the circulator, no starting current there, if it doesn't light its a bad relay.

I've seen "resistence connections" that allow voltage to flow until put under load.

 

[Redox]

I don't think it is really rated for motor loads. Try inserting another relay after the 70S2 and see what happens.

Anyone ever use these: http://www.functionaldevices.com/chartRelays.html All the commercial automation guys I know love them.....

Chris