Need help wiring a 380v motor with switch and light bulb 3

[BTritle]

I need help with a new machine design.
A customer is requesting a 380V 3-phase 50HZ 1HP motor on a machine. The motor will run a single speed for a grinding operation. They will be supplying 380V 3-phase.
Our machine also has a incandescent work light that typically matches/uses the input voltage supplied. What voltage and/or light bulb should I use for the work light? Do I need to step down voltage for the light, and if so, how would I go about doing this? (what is the common lighting voltage for 380V machines?)
Also the customer has requested a lighted on/off switch for the motor. I am searching for a possible switch but having no luck.
There is a possiblity that I can use a panel mounted indicator light that would signify the motor is powered on.
Any help would be much appreciated.

 

[automatic2]

step down to 120v for lighting, control. Will also give you convenience outlet for service work.

 

[Skogsgurra]

Most 380 V grids also have Neutral available. If that is so, you will have 220 V between phase and neutral. No transformer needed. And 220 (230-240, rather) lamps are standard in those parts of the world where 380 (or 400 V) is common.

I do not think that your customer will be very pleased to find a 120 V outlet on his machine if he has 230 V hand-tools.

You should ask the customer about this. We can only guess.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[BTritle]

What would be the cheapest method to step down to the 120V circuit?
Is there a way to switch this small motor without a contactor? Is there a common switch that would handle the motor draw and safely disconnect all leads from the 380V?
I am assuming that when using a contactor for motor control in this situation, I could use the 120V circuit and switch to trip the contactor. This would also illuminate a motor on indicator light or illuminated switch.

 

[automatic2]

you do want a starter for the motor. If it's only ON indication, you can insert a control transformer that won't break the bank, yet give you enough current to pull in the contactor with indication.

 

[jraef]

I don't mean to be rude, but please pay heed to skogsgura's advice. One of the best ways to lose your client's respect is to try to force him to do things your way when it is completely foreign to his way of doing things. As Gunnar (skogsgura) said, 99% of the time a 380V 3 phase supply will include a neutral, so the normal way of doing something like this is to use one of the line phases and a neutral which will give you 230V. Then all you need is a 230V light bulb. Normal, easy to find and replace in his country, that is the way he will be used to seeing things like this. if you insist on 120V, he will be cursing your name when he needs to replace that bulb because he will not find a 120V light bulb in stock anywhere in his country.

As to the motor control, if this is a simple manual operation such as on a bench grinder, you will still need to provide running overload protection for the motor. You need to supply a simple manual motor starter. The type used in most IEC countries (meaning not North America) is a very simplistic manually operated device with a on-off button or switch like a light switch along with an adjustable overload trip element. Here is an example:

motor protectivce switch

 

[BTritle]

Thank you everyone that have replied. Your information has been very helpfull.
Can someone please clarify one thing for me? Is it OK to tie the neutral to ground in this situation? Or will there be a seperate ground with the 3 phases and neutral?

 

[waross]

There should be a seperate ground conductor.
respectfully

 

[Skogsgurra]

There are two systems used in Europe. The TN-C and the TN-S systems. See

http://en.wikipedia.org/wiki/Earthing_system

for an explanation.

The TN-C system has a combined PE and N conductor and does not need two separate wires for PE and N (that's the reason for the "C" - as in Combined).

TN-C systems are a lot more common than TN-S (you guessed it, "S" stands for Separate). In both cases, there are two separate conductors going from the fuse-box to the machine.

The N is light-blue and the PE has yellow/green stripes. You are not allowed to connect anything current-carrying to the PE - all single-phase returns shall go to N.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jraef]

By the way, "PE" means Potential Earth; what we call "Ground" in case you were unfamiliar.

 

[ScottyUK]

I've always understood PE to be 'Protective Earth', colour-coded green/yellow, as distinct from functional earth, colour-coded cream. But absolutely right, it is the equivalent of 'ground' in the US.

There's a good summary of the European harmonised colour code in this link:

http://www.iee.org/Publish/WireRegs/IEE_Harmonized_colours.pdf

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Sometimes I only open my mouth to swap feet...

 

[jraef]

Yes, just saw that on the Wiki site too ScottyUK. Being an American, I only picked up stuff like that from Europeans I have worked with over the years. I never thought to question that when my English boss explained it to me years ago at one of my first engineering positions with Klockner Moeller. I now stand corrected, but I assure you I will not forget that... for whatever it's worth.

It will at least serve to bolster my wife's perception of my being "a fountain of useless information".

 

[ScottyUK]

Maybe our wives should meet and collaborate on a book entitled 'Engineering Insults for Your Spouse'? Although mine seems to manage quite well without any assistance!!


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Sometimes I only open my mouth to swap feet...