Vaccum Pump with Solid State Relay

Hi again !!!!

I got the trick which works as my perception, I have connected diode (with series 100K, 2w resistor) in revrse polarity than the diode built in the Vaccum pump...

Now the circuit works properly as it should.

I got the solution but it will be good if anyone can explain me the exact reason for such behaviour of the solid state relay...

Regards !!

Something sounds a little fishy . . .

How are you applying the 5 VDC signal to the SSR?

Is the SSR an AC output type?

Does the pump actually have a DC motor?

The solution you arrived at doesn't make a lot of sense, so more information would be helpful.

Hhhhh...

SSR rating:: 230v Ac, 10 Amp @ o/p side and 5 Vdc @ i/p side.

Vaccum pump rating is:: 230 V ac, 14 watt.

Here Vacuum pump has two pieces of coil inside it with a series diode in between them. I think it works like a plunger i.e. electromagnet... During +ve half cycle of AC power, coil get energized and for -ve half cycle it got dis-energized...which may be the working principle of the pump...

Pls correct me if i'm wrong...

Let your idea begin to flow......

regards!!!

Ahhh!

I think I may know the problem!

The SSR may be the type that operates at each zero-crossing of AC, and therefore one of the possibly back-to-back SCR's internal to the relay don't get fired unless the reverse current through the SSR you have provided with the external resistor and diode is present. Do you apply 5VDC continuosly?

Hi!

Thanks for the response...

I have also applied 5V dc continously .....

But my original operation requires On and Off of 5 vdc at user necessity..

Regards!

Lack of back emf on the four-layer device (scr or triac) in the solid state relay would prevent it from switching off. I encountered a similar problem several years ago when using a large silicon diode to limit the brightness of an incandescent bulb connected to a consumer-type lamp dimmer. My solution was to bypass the diode with a large wirewound resistor from my junkbox.

Solid state devices are almost the equivalent of the electromechanical devices they are designed to replace, but not quite.

Perhaps there was enough DC from the diode in the pump that the scr/triac in the SSR (Solid State Relay) never released the circuit. Your additional diode blocked the DC to allow the SSR zero crossing to drop the load. I have seen some strange things happen when attempting to switch DC loads with an AC SSR.

There are solid state relay with SSR inside them that have zero crossing others with no zero crossing trig and solid state relay with FETs . What kind of solid state relay do you use? You can not in same application use whatever you like unfortunately i am not understand you circuit by your description.

Just a thought. This could be something simple.

Does the pump have a on/off switch that you keep turned on for this operation? Allot of equipment that I have used for jobs like these have protection circuits that don't allow the unit to function if the AC mains are removed unless you toggle the on/off switch.

By removing the AC with the relay you may be causing it to go into shutdown.

Just a thought. I may be WAY wrong and usually are. But thought I would throw this out there for funnsies.

bill12780

Obvious reason. SSR can start only near voltage zero cross (due to device design) and shut only near current zero cross (due to SCR or TRIAC use in the device) i.e. can only be properly used on (both voltage and current) AC. Using a diode on your load is no longer AC , just bad quality DC. But you could make it work just by attaching a small capacitor ~ 1nF on SSR output. This will give some AC current load and minimal losses