Power Consumption of Motor Starters when Holding (Energized)

OOPS!I accidentally posted this on more than one forum: (Electrical Engineering and General). Left hand does not know what right hand is doing.Sorry 'bout that.

You seem to be asking what the wattage is for holding in a magnetic coil on a contactor...For DC control voltage I think this is determined by the resistance of the magnetic coil winding...When energised from a 120 volt AC supply, there is also considerable inductive reactance.

Both combined, the impedance, determines the current drawn by the coil....I haven't seen them draw much more than an amp...

https://forums.mikeholt.com/threads/coil-ohms.1468/

I know how to measure any particular coil,but I wanted to know what different NEMA sizes of coils consume while holding.There are some pretty large motor starter relays(contactors) out there,and I am sure they require more than an amp to hold.

A NEMA size 7 is rated for up to 1000 hp.(contact rating,and a very large coil to energize)There should be some specs for this,but I have not been able to find them.

Even if only 1 amp is required that is still a lot of energy world wide.

The amps required depends on the voltage...

I guess you could go with motorized switch disconnects, might be a more expensive I'm guessing...

https://new.abb.com/low-voltage/products/switches/motor-operated-switch-disconnectors

Amps vary but the power is the same...16VA.

Multiply this by all of the motor relays that are energized at the same time across the USA and that is a lot of energy just holding relays.I am thinking that maybe a latch to hold relay in after energizing,and a Piezo release that could be triggered when drop out is required or when power fails if they are designed to fail safe when off.

The most energy by far is used when initiating contact...maybe a capacitor start magnetic coil would work...?

You're certainly right that 16VA multiplied by the huge number of motors running is a pretty fair amount of energy. On the other hand, that energy is presumably a pretty small fraction of the energy used by the motors themselves.

Are you suggesting he's being penny wise and pound foolish...? I think the best solution would be to reduce the cost of the energy in the first place...this would save both the penny and the pound...

https://www.eia.gov/todayinenergy/detail.php?id=57280

Is nuclear energy the most efficient energy source? As a matter of fact, even energy.gov says "...and it's not even close!" Nuclear has a 92.5% energy factor. The energy density of uranium is what makes it so much more efficient than any other fuel source. It literally contains millions of times more energy per mass than any other fuel source!Jan 17, 2023

When you have to eat an elephant,you do it one bite at the time.

cookies? Well ok.

I tried,but those refrigerator magnets are too tough to chew.

Life is like that sometimes.

It depends on the elephant.

https://www.cookielicious.co.nz/all-about-cookies--blog/archives/10-2015

It's tiny in comparison with the lighting load. Start there first.

Even a nibble is something.

To fell a building,start at the bottom:Therein lies the foundation.

"It is better to light a small candle that to curse the darkness"..Proverbs 4

Duplicate thread.

Please refer to my first post#1

I found this that utilizes composite Piezo actuators that hold with no power applied.

https://www.techbriefs.com/component/content/article/37328-self-latching-piezocomposite-actuator

Looks like this is a good candidate for motor starter relays.Even lighting loads have a relay that stays energized..A lot of energy could be saved by using this technology on all relays on a replacement basis.Backward compatibility would not be a problem.Replace a coil with this actuator built in the same mechanical dimensions as the coil it is replacing.Instant drop out with a short pulse from a capacitor.