Wasted Power of Solenoid Valves

Latching solenoids require a more complex drive circuit of course as the drive pulse must be of the correct polarity.
As we know complexity leads to unrelability.
I believe latching solenoids (or at least the low power one I've used, in a battery chemical delivery system) can get knocked into the wrong as there is no positive action, this could be hazardous in some applications. Indeed they have no predetermined state and thus need carefull initialisation.
You are correct of course, but the power savings are possibly only worthwhile in battery operated equipment.
Del

Hi Del,

The valve I am talking about is a two position, bi stable, solenoid pilot operated, solenoid pilot reset, pneumatic valve, used in all sorts of applications and industries in electro pneumatic applications.

When the coil is energised the valve spool is moved and will stay there forever or untill it is signaled to move by the opposite solenoid. They are usually 24vDC & 110vAC but can be any voltage.

If I understand you correctly a latching solenoid requires a residual current to hold it in position, the same as a solenoid pilot operated, spring return valve needs a maintained signal to hold it's position.

Thanks for the feed back,

Best regards,

John

The one I used required a 6volt pulse of about 50mS to move it one way and a pulse of the oposite polarity to move it t'other. No residual current, thus great for batter application. It has just one coil and latches magnetically.
Del

Hi again Del,

In my 40 years in pneumatics I've sold Martonair (now Norgren), SMC, Mindman, Chellic, Pneumax, Metalwork & Univer as well as most other manufacturers (Camozzi, Ross, Waircom, Kay Numatics, etc.) in mainly industrial and civil engineering. Not come across the type of valve you describe.

We live & learn,

Best regards,

John

Ah, well I s'pose it's not specifically a 'pneumatic' solenoid valve. I let drain dosing chemical flow through it under gravity.
Dunno if there's any specific difference between pneumatic solenoid valves and fluid ones?

Del

In a plant there are some systems which would under an abnormality of severe nature or an emergency should completely shut down the whole section of a plant or the plant in total.

An electric actuator or solenoid as you call it has besides the output shaft an auxiliary shaft to operate limit and torque switches for open and close movements. Usually this shaft also drives local and remote position indicators, plus banks of additional limit switches for other interlocking and control functions.

All types of actuators can be arranged for remote manual control and/or automatic operation in conjunction with centralized control systems.

For any crucial system to tackle emergencies by bringing a plant to shut down and to provide interlock functions, fail safe power supplies is a requirement.

you can fulfill your ambitions of power savings at routine functions in a plant but normally not with an actuator.

ga - save where operations and safety are not affected.

Hi,

The type of pneumatic solenoid operated valve I am talking about is that used to operate a pneumatic cylinder (actuator).

In many cases there is a set of contacts embedded in the solenoid actuator that removes power from the coil once it has moved the shaft past the desired point. So from an external standpoint it may appear as though you are keeping power on the coil, but in fact you are not, the circuit is broken inside.

If this were not done, the coil may burn out if energized continuously. On small DC coils the sealed coil power consumption is too small to make this worthwhile however, i.e. 1-2 watts.

Hi JRaef,

I would draw your attention to my previous answers as to the type of valve I mean, it is not an electrically operated actuator.

Best regards,

John