about a continuous duty AC solenoid 2

[richardgb]

and the question is for a continuous AC solenoid :

1. When the solenoid has pulled in the mechanism,
is it mandatory that the electricity gets shut off ?

2. Or can the AC stay on and keep on building the electric field,
so that the solenoid stays magnetized ?

3. Will the continuous duty solenoid overheat and burn out ?

4. Is there any difference between an AC and a DC solenoid
in regards to this simple question.

Thanks for any answers or ideas at all.

 

[rbulsara]

1. No, if designed for continuous duty.
2. Yes, if designed for that purpose.
3. No, provided voltage and environment is within its spec.
4. Not really. Both are as good as their design and application.





Rafiq Bulsara

http://www.srengineersct.com

 

[amptramp]

4. AC coils use a "shading coil" to keep the magnetic field from collapsing at zero crossing of the ac signal. The shading coil prevents the solenoid from chattering.

http://www.detroitcoil.com/PAGES/What Is A Solenoid.pdf

 

[itsmoked]

The single most important difference between DC and AC is that the reluctance of the AC solenoid changes as the solenoid plunger pulls in. When seated the current drops substantially by about 10X. This allows AC solenoids to pull in extremely hard with large current but once pulled in the holding current drops to a very low value.

If you prevent an AC solenoid from pulling in it will normally burn up in about 1 second unless it's a weak solenoid or has thermal protection.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Some DC solenoids have an economizer winding. There is a heavy winding that draws a lot of current and pus the solenoid in. The plunger operates a circuit that puts a many turn economizer winding into service to hold the solenoid in place.
Some designs disconnect the heavy winding, some designs put the economizer winding in series with the pull-in winding.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[rhatcher]

I agree with waross except to add that some designs put a resistor in series with the coil once it is closed.

 

[waross]

Yes, I agree, rhatcher.

Bill
--------------------
"Why not the best?"
Jimmy Carter