SSR Issue

[Rhinestone]

Hi,

I’m trying to control a 24 VDC pump through a Crydom CL240D10C solid state relay. I’m triggering the relay from a NI myDaq 5v output and the relay seems to be operating fine with no load connected but when I connect the load and trigger the relay the pump doesn’t run. If I trigger the relay and connect the pump after then it does run. Apologies for the stupid question but any idea what I’m doing wrong? I’m switching the 24v through the relay output to the pump. See wiring diagram attached for how I have it connected.

Bryan

 

[rjenkinsgb]

Does the relay work OK if you use a separate power source with the pump already connected?
If not, the relay seems to be faulty.

Do you have the control side negative wired directly back to the control system? If it's sharing a ground return with the power circuit at any point, there could be interference or voltage offsets messing it up.

A DC motor will pull several times its rated current when first started, so an apparently low resistance shared connection can have quite a voltage spike on it during the motor start.

 

[Rhinestone]

Does the relay work OK if you use a separate power source with the pump already connected?
If not, the relay seems to be faulty.

Do you have the control side negative wired directly back to the control system? If it's sharing a ground return with the power circuit at any point, there could be interference or voltage offsets messing it up.

A DC motor will pull several times its rated current when first started, so an apparently low resistance shared connection can have quite a voltage spike on it during the motor start.

The relay is triggered by a seperately powered controller and the negative is also wired back to this source, nothing shared with the pump supply other that the 230v mains supply.

 

[danadak]

That relay module is for controlling a AC load. It can handle
DC or AC input control signal, but its load has to be AC.

Regards, Dana.

 

[rjenkinsgb]

I missed that!
The one in the diagram is shown as being 100A 30V DC - but as Dana says, the Crydom one you give the part number for is for controlling an AC load, not DC.

You could switch the AC input to the pump power supply?