Hit and hold circuit for AC Solenoid valve

Thread Starter

srikanthgedela

Joined Jan 23, 2021
1
dear all

can any one help me out in hit and hold circuit for AC solenoid valve. I am turning on 230v ac solenoid valve for 30min and its getting heated.
I there any way to avoid the heating of coil. For DC solenoid valve is use to achieve this by DRV103.
 

crutschow

Joined Mar 14, 2008
27,170
I
The TS needs to drive an AC solenoid. Maybe a DRV110.
Ahh, I missed that. :oops:

I suppose you could use a TRIAC type dimmer circuit (such as this) to reduce the voltage for the AC relay coil after energizing at full voltage, (which likely will cause some buzzing in the coil).
You then could use a delay circuit (such as a 555 one-shot or a simple RC delay) to switch in a resistor (such as with this small relay) that changes the dimmer from 100% to whatever dimmer setting keeps the relay pulled in.

Would be likely easier to power the coil from DC and use the DRV110 to reduce the voltage.

Of course either way requires a DC supply.

srikanthgedela, what are the coil characteristics (coil resistance, inductance, current) of the relay you are energizing?
 
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crutschow

Joined Mar 14, 2008
27,170
It should run cooler than the AC variety.
Why?
The AC coil has inductance that helps limit the coil current without loss.
The DC coil has to limit the coil current only with lossy resistance.

Is it AC eddy-current loss that makes the difference?
 
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MaxHeadRoom

Joined Jul 18, 2013
23,084
The only advantage of a AC solenoid, relay, contactor coil, is at switch on (high current inrush) , after that, devices or means have to be instituted to keep it retained through zero, heat producing shading ring etc.
The DC coil solenoid once energized requires much less voltage/energy to remain retained, also no frequency buzz.
With an AC coil, if anything stops it from shifting over, or someone inadvertently pushes a valve solenoid for example, when energized, it immediately fries the coil.
N.A. was lagging in the fitting of DC solenoid devices over Europe, which has typically used them for machine tools etc for decades
When I specified them for a custom made machine for the company I worked for, I got push back from their engineering dept, their response was, "we have always done it this way"!
After my employer at the time went over to DC solenoids on my recommendation , the spares inventory of them dropped dramatically! :cool:
Max.
 
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