Inrush current solenoid valve 1

[ECM1]

I was wondering if there is anything that could cause a greater inrush current in a pilot operated solenoid valve. Such as water pressure.
Also I have been told that a vacuum is created when a valve opens that will restrict the movement of the solenoid plunger increasing the inrush current.
Is there any truth to all of this?

 

[JLSeagull]

Search for information from the solenoid valve manufacturer. Following are Power Consumption guidelines from the ASCO Engineering Bulletin:

"Power consumption can be determined from the ratings shown on individual Series pages. For AC valves, the watts, volt-ampere “inrush” (the high momentary surge occurring at coil energization), and volt-ampere “holding” (the continuous draw following inrush) are given.
The current rating for inrush and holding may be determined by dividing the voltage into the volt-amp rating.

DC valves have no inrush current. The amp rating can be determined by dividing the voltage into the DC watt rating."

 

[gerhardl]

What is your real problem?

If this is an 'after the
fact question' or question for planning purposes: are you sure your solenoids and circuits are properly electrically protected / with correct solenoid choice?

Some solenoids have inbuilt protection.

 

[ECM1]

The problem that I'm having a heated debate dealing with inrush current of valve solenoid.

Everyone else is contending that the higher the water pressure is, the higher the inrush current will be. My position is that the inrush current will stay the same.

I believe is that the time it takes for the inrush current to go down to the holding current might increase by a nano-second if any due to the higher water pressure on top of the plunger. But the inrush current will stay the same regardless.

It has also been suggested that once a valve opens, that a vacuum is created by the water exhausting out to the discharge side of the valve, this will create a greater pull on the solenoid plunger, creating a increase in the inrush current. I disagree with this as well.

Any thoughts.

 

[roydm]

First of all a pilot operated solenoid isn't effected by the water pressure. The Pilot valve is a small solenoid that switches the media, which in turn acts apon a large piston or diaphragm that opens the main valve. An ASCO 8210 would be a good example.
A direct acting solenoid on the other hand operates the valve directly, they tend to be small port low flow or low pressure valves e.g. ASCO 8030 series only rated at 15 psid.
Most solenoids are rated in differential pressure which means that a valve on 100# to vacuum is the same as 115# to atmosphere.
I agree with you, the inrush current will stay the same (I assume we are talking Direct Acting AC Coil) but as soon as the valve breaks the seal between plunger and seat the pressure acting on the plunger is about the same in both directions. When the plunger completes the magnetic circuit the impedance goes up and the current goes down to Holding value.
To cap it off as long as your valve is rated to 15# over your line pressure you can forget about any effect vacuum may have on it.
Regards
Roy

 

[gerhardl]

...once again showing that a technical question is better answered if you have a broader view on the context and background.

roydem has given in my opinioin a very good and precise answer.

The only thing I think to be added is the simple fact that your collegues probably are mixing the necessary force (here selected solenoid type/size and construction necessary to do the process task at hand) with inrush current.

Once you have selected a certain type/size solenoid the inrush current will be as given by roydem: remain with natural variations approximately the same.

If you select a larger solenoid the inrush current will be different.

 

[waross]

You are correct.

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