Control Voltage For Motor Starter

110VAC and 24VDC are common.

in a typical control circuit voltage is used to pass through safety controls and ultimately to something like a starter , contactor, switch, etc to turn a device on or off.

control voltage is usually but necessarily a lower voltage than "line voltage that is used to actually operate the motor, compressor, fan, pump, etc in the machine.

so generally "control voltage" is a lower voltage than line or load voltage. it can be AC or DC, but is usually the same as the line voltage,but not always. you can have controls that handle AC loads that are controlled by DC, or even air can control( but that wasn't your question)

Any voltage you like. But to meet safety requirements you need to check you're local codes.

Also bear in mind the availability of spares in you're locality.

spare what??????

Spare coils.

I have seen many times where people specify a coil voltage without thought to availability. An example is 48VAC coils. Some EE decides this is is a solution to a problem and specifies it, but when the equipment gets to the field and a coil goes bad, the user discovers that nobody stocks them and the manufacturer only builds them to order.

I used to work for Siemens, that was the exact case with 48VAC coils. We only made them once per year because of low demand. So if you ordered some right after we ran out of them, you might wait a year to get them from the next batch. That can be a MAJOR downtime issue.

if you supply a 48V with 230 volts it just works faster, right?

Now I wonder why I was thinking of 48V coils made by guess who when I mentioned spares.

Contactor coils.

Contactor coil control voltage. The main part of a motor starter is a contactor which is controlled by its coil.

Here is the basic concept.

The illustration below shows a contactor (M) control circuit that is using the Line Voltage as the control (coil) voltage. If you do not want that, you take the Line Voltage, in this case L1 and L2, to a Control Power Transformer and step it down to something else more palatable. For example here int he US if the motor voltage is 460VAC, we use 120VAC quite a bit because it is considered somewhat more "dangerous" to run 480V to the control devices like the push buttons on the door. If you do that, then the coil voltage will be 120VAC, even if the motor voltage is 460VAC.

In IEC systems, the Line voltage is often 380V Y, so the control voltage is often derived by connecting one Line voltage terminal and a Neutral terminal to get 220V as the control (coil) voltage. But that too is less than optimal in many cases and there is a trend toward using 24VDC to be safer.

u have a good helping mentality. good luck

Your post deserves a GA.

What type of motor do you have three phase or single?

The control voltage for a motor starter is basically the voltage which controls the functioning of the starter components. A starter may have safety circuits, interlocks, remote switches, guages & meters etc for its safe and efficient opeartion.

The control voltages are generally lower than the line voltage. However, some low voltage starters, same line voltages also are being used. Conversion from ac to dc and vice versa is genreally not done as it become expensive and bulky.115V or 220V (single phase) are commonly used control voltages for 3 phase motor starers.