Solid state relay

[Flatech]

I am powering a solid state relay using 15vdc. When I turn it off, my output still remains ON. If I physically remove the input 15vdc wire ( plus or negative side ) my output turns OFF. To me, it sounds that I still have enough current on the input to maintain the output ON. How do I discharge that voltage coming in to the solid state relay when I turn off input power? BTW, the LED on the SSR turns off and on, no problem. Just the output not following the command.

 

[ericgibbs]

hi,
When you switch OFF, is the Control wire to the SSR 'floating' ie: open circuit.???
If Yes, connect a 10K resistor from the SSR Control pin to 0V. Leave the 10K connected.

 

[Flatech]

I am not sure if it's an open circuit. If a fault is created, I do not see that 15vdc present with my voltmeter any longer but the output remains ON. Do I place this resistor in series with the wire going to negative on the input voltage to the SSR? Thanks.

 

[ericgibbs]

I am not sure if it's an open circuit. If a fault is created, I do not see that 15vdc present with my voltmeter any longer but the output remains ON. Do I place this resistor in series with the wire going to negative on the input voltage to the SSR? Thanks.

Connect the resistor across the SSR control pins.
How are the SSR pins named on the device.????

 

[Flatech]

It says A1+ and A2-. Of course, A1+ is 15v and A2- is 0v. So just put a 10k resistor across these pins?

 

[ericgibbs]

It says A1+ and A2-. Of course, A1+ is 15v and A2- is 0v. So just put a 10k resistor across these pins?

OK, Try the 10K across A1 and A2.

There should be 4 pins.???

 

[4pyros]

To me, it sounds that I still have enough current on the input to maintain the output ON.

What is driving the SSR?

 

[Flatech]

This is an application where we are using a fume extractor during laser coding. If the fume extractor cloggs up, it sends this 15v out. Not sure where it comes from, it's irrelevant I guess. We have to use this 15v on our laser circuit board but we wanna isolate it using an SSR. The SSR has two pins for the input A1 and A2, that's it. The output has 24v, ground and signal, so 3 pins, we know how to connect the output, no problem. The only issue is the output stays ON, even though the input changes to 0v, well we are assuming is 0v because we lose the 15v. This SSR is one of those green flat ones, where you snap onto those electrical rails inside an electrical panel.

 

[KMoffett]

The output has 24v, ground and signal

Is the output side controlling 24V DC or AC? Do you have a manufacturer and part # for the SSR or a link?

Ken

 

[Flatech]

The output controls 24vdc. The manufacturer is Weidmuller and the part # is 8937990000 MOS 12-28vdc 100kHz.

 

[KMoffett]

Can you post a schematic or sketch of how you have the input, output, and load wired. Picture worth a thousand posts...yah 'now.

Ken

 

[Flatech]

There is the device and the way I have it wired.

 

[Reloadron]

Doing some digging I located the complete data sheet for your specific part number.

Continuous current max. 50 mA

What sort of load is this driving into?

Ron

 

[Flatech]

the output goes to i/o circuit board. it applies 24vdc to an input on the board. it gives out a warning on a display that the fume extractor is clogged.

 

[KMoffett]

At this point I'd phone or email Weidmuller tech support.

Ken

 

[Flatech]

I am gonna try the 10k resistor across my input and see if my output changes state.

 

[KMoffett]

Have you tried to put a known load across the output...say, 10K from output to ground?

Ken

 

[Flatech]

I can try that tomorrow. Do you think it's a better approach placing that 10k in the output than in the input? Sorry, I don't have much expertise in electronics. Thanks.

 

[KMoffett]

The datasheet shows that the output has some current leakage ("<20uA"). If the output drive is a PNP pull up, and the load has an extremely high resistance and has a capacitance to ground it could charge when ON and not quickly discharge when OFF. The 10K on the output might pull it to ground when OFF. But, there isn't enough info in the datasheet about that. Again, contact the manufacturer.

Ken

 

[Flatech]

Thanks so much for the advice.