ok thanks i kind of figured that but i have a 2 va dc.transformer and it got hot running 2 valves on the bench for testing and even real warm on 1 valve. but that was a dc transformer and that might have been why it got hot. thanks
Firstly, there is no such thing as a "dc transformer". Transformers operate on ac. You can create dc by connecting the transformer secondary to a diode rectifier. Secondly, solenoid-controlled valves come in two types: ac solenoid coils. and dc solenoid coils. The main difference between the two types is how the magnetic circuit for the moving solenoid plunger is constructed.
An ac solenoid coil will be specified to operate at a certain ac rms voltage, anywhere from mains voltage down to some lower voltage, such as 24 vac, derived from a step-down transformer connected between the mains and the solenoid load. A dc solenoid coil
requires direct current excitation. So it is important to know which type of solenoid you are trying to actuate.
An ac solenoid has an ac
impedance that is different than its dc coil
resistance. This impedance varies from some minimum value before the solenoid is energized to a maximum value when the solenoid plunger is "pulled in". This happens because of physical changes in the magnetic circuit. A dc solenoid has a dc coil resistance that is constant, whether the solenoid is energized or not.
The fact that your solenoid valves specify an in-rush current that is considerably larger than the holding current indicates these are ac solenoid valves. DC solenoid valves do not typically exhibit this effect. A dc solenoid valve will have an operating voltage (or current) that is larger than its minimum holding voltage (or current), but this is attributed to physical changes on the magnetic circuit: as the plunger is pulled into the solenoid, the magnetic force moving the plunger increases until it reaches a maximum value when the plunger is mechanically stopped. It then requires a reduction in the voltage (or current) applied to the solenoid before the solenoid spring can return the plunger to the de-energized position.
It is most likely that you are using 24 volt ac valves that use 0.2 A per valve when the valve is actuated. Your valve uses up to 0.5 A per valve when first energized (the inrush current specification). To be on the "safe side" your transformer should be able to provide a continuous output of 0.5 A per valve, as
@AnalogKid in his post #4 above described. So, 24 vac transformer providing 2 A continuous current to four valves will require a 48 VA transformer. A larger transformer with a larger 50 VA rating is okay.
More than you probably ever wanted to know about ac versus dc solenoid valves can be found at
this link.
