Number of poles for circuit breaker when using 230VAC power to a motor on international power 5

[kjoiner]

Hello,

We are revising the power section of our machines to allow the use of 110VAC or 230VAC single phase for domestic and international use. We already use switching power supplies so DC power output is not an issue. We also use a an AC gearmotor that runs on line voltage. To address the gearmotor, we are selecting motors with dual windings so they can be set up for 110VAC or 230VAC.

The question I have relates to a circuit breaker to protect the motor. Over the years for the 110VAC we have used a 1A push button resettable breaker that is wired into the hot line. I plan to select a DIN mount breaker to replace the push button breaker as part of other design changes.

For international, 230VAC can I still use a single pole breaker but with 1/2A rating? International wire colors are brown(hot), blue (neutral) and green/yellow (ground). Is the brown wire always the hot wire? I'm asking because I've heard that cords with plugs are not polarized like they are in the US and either prong could be the hot. I'm hoping that as long as I put the breaker on the brown wire I can protect the motor and cut power to it if needed.

Thanks!

 

[LittleInch]

"International" is very vague.

There are many different plug types in the world outside the US and many are 50 Htz not 60.

Many two pin plugs can be inserted any way around.

Single pole may stop the motor but not always isolate the supply of your using corded plugs.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[kjoiner]

""International" is very vague."

That's exactly my concern. I see numerous types of plugs - some two pin, some three pin etc. depending on which country.

For switching main power to the entire machine, we are using a two pole switch to ensure we get both the hot and neutral no matter which way they are wired. I think we will have to use a two pole breaker for the motor to account for these wiring differences as well.

I do find it odd that for all of the safety requirements for CE and other certifications, polarization of power outlets and plugs is not a major requirement.

 

[wayne440]

My opinion, claiming no expertise is that you should use a two pole breaker for the "230VAC" application. Because someone at sometime will bring that machine to the USA and plug it in to 240VAC, where there are 2 "hot" leads.

 

[waross]

Only one pole is needed for control and protection of the motor.
Two poles will be needed in some instances for safety isolation.
If you use two pole breakers, you will not have to worry about special circumstances.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Compositepro]

In the US 240 VAC is between two hot wires with each being 120 VAC to ground. International 240 VAC is sometimes (often?) between one hot wire and a grounded neutral wire. It is not so simple to accommodate both types of supply.

 

[jraef]

Just out of curiosity, how are you dealing with the frequency issues if it is the same motor?


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[wde0665]

My limited experience with European 230V, at least on the imported non-Americanized company-built plant equipment forced down our throats by the corporate design engineers across the pond striving for a universal one-size-fits-all everywhere machine design, was that both legs were hot respective to ground, IIRC, many times just picked up 2 phases of the 3 phase 400V supply without a control transformer.

Again, IIRC, their control power breakers were all 2-pole.

Quite the challenge 400V vs 480V, 50Hz vs 60Hz, shoe-horning equipment from over there to make diapers over here.

 

[LittleInch]

Different places do different things.

Some do just pick up two phases, some have TP&N and just pick up a single phase for one house, then a different phase for the next house etc.

But Europe is 50Htz, 230V.
Some places are in reality close to 250V, some closer to 215.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[kjoiner]

Hello,

Thank you for the answers and information. Here is some additional information and background.

In the past, we used an autotransformer to drop the voltage from 230 to 110. Going forward, we want to avoid this since it's an additional supply chain issue and some customers do not like having an autotransformer.

jraef: Good question. The motor will run at 83% of the speed which should be acceptable since we have run at 50hz in the past.

I believe the best option is to use a 2 pole breaker and switch both the hot and neutral to ensure power is completely cut to the motor.

This leads to another question. Some countries have 2 conductor plugs with no ground. We run grounds on all of our components.

Do international countries use GFCIs? For UL751, we have to use a GFCI.

 

[LittleInch]

There is no such thing as "International countries"....

Many plug systems are simply two pin, but often allow for a three pin with earth connection, but even then usually allow the two pin connection to be used....

So unlike the US earthed plug, you can easily plug an earthed European plug into a simple 2 pin socket with no earth. Except the UK which has a bigger earth pin plus it activated a shutter mechanism to prevent access to the live sockets with a two pin plug. Not foolproof, but by far the best consumer electrical system I've seen.

Some have different sized pins for different capacity plugs which complicates life considerably.

If you have systems which could become live and need and earth then these need to be double insulated to prevent electric shocks in the absence of an earth connection....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[kjoiner]

Hello,

LittleInch -There is no such thing as "International countries"...."

You are correct. Basically, I want to be compatible with countries outside of the US and Canada where voltages and frequencies are different.

I will be working closely with our testing lab to evaluate performance and safety requirements.

 

[waross]

Going from 50Hz to 60 Hz or from 60 Hz to 50 Hz, be sure to use the 50/60 or 60/50 ratio for both speed and voltage.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!