Need Help!- Wiring 220V and 110V inside of CNC Electronics Cabinet

[MRM RCModels]

Electronics are not my fortay, so I have a simple question for you guys. I have one Hitach VFD running off 220V and a power supply + CPU both running off 110V; all in the same control box. I would like to run one 220V cable to the control box for simplicity. Would there be a way to convert the 220V to 110V inside the cabinet so I can power all the components from the same line?

Thanks ahead of time,

MRM

[irving2008]

Originally Posted by MRM RCModels Electronics are not my fortay, so I have a simple question for you guys. I have one Hitach VFD running off 220V and a power supply + CPU both running off 110V; all in the same control box. I would like to run one 220V cable to the control box for simplicity. Would there be a way to convert the 220V to 110V inside the cabinet so I can power all the components from the same line? Thanks ahead of time, MRM

I would have thought a small 220 - 110 transformer would do the job. You need to find one whose wattage (or VA) rating is about 10% higher than the powersupply and CPU need together. But check to see if the power supply and CPU can run off 220v... mine are all rated 100 - 240v which makes them pretty universal (there may be a switch or something to configure them).

Just a thought - 220v might be 3-phase? same applies - need to run the transformer off one phase thats all..

[TOTALLYRC]

Originally Posted by MRM RCModels Electronics are not my fortay, so I have a simple question for you guys. I have one Hitach VFD running off 220V and a power supply + CPU both running off 110V; all in the same control box. I would like to run one 220V cable to the control box for simplicity. Would there be a way to convert the 220V to 110V inside the cabinet so I can power all the components from the same line? Thanks ahead of time, MRM

Hi MRM,

The way that 110v volt is brought in your fuse panel is 2, 220v legs and a neutral. At least in American homes with single phase service.
One leg and the neutral give 110v. If you are adding a lot of 110v devices inside the cabinet, try to split them between legs to balance the load on the 220v legs.

If you are running the 220v line yourself, make sure you use a 3 wire cable with ground, this was you get leg, leg, and neutral.

Red and black are the 220v legs and the white is the neutral.

If you are unsure, ask a licensed electrician.

Disclaimer, I am not an electrician but I play one on the CNCzone.

Mike

[TOTALLYRC]

Irving2008 has a good point, many computer power supplies have a switch on the back that gives voltage selection.

Mike

[ger21]

The method Mike mentioned is used on electric ovens and clothes dryers to provide both 110V and 220V. You can get the wire at home depot.

[TOTALLYRC]

Originally Posted by ger21 The method Mike mentioned is used on electric ovens and clothes dryers to provide both 110V and 220V. You can get the wire at home depot.

It is also used on both my CNC mill and soon to be CNC lathe so I know it works.


Thanks for the backup Gerry. Always nice to know I got it right.
Mike

[irving2008]

INteresting about the split supply, didnt realise that was the case in US. UK homes have a 240 single phase supply on 3 wires , Line, Neutral and Earth. This is one phase of the 3-phase 415v transmission and the balancing is done at the local substation across streets, or even within a block of flats (apartments). Domestic 3-phase is generally not available unless you are lucky enough to live in a warehouse conversion or similar.

[Torchhead]

Originally Posted by TOTALLYRC Hi MRM, The way that 110v volt is brought in your fuse panel is 2, 220v legs and a neutral. At least in American homes with single phase service. One leg and the neutral give 110v. If you are adding a lot of 110v devices inside the cabinet, try to split them between legs to balance the load on the 220v legs. ...

The only thing I would add to that is that the US configuration is actually two legs of 120VAC, 180 degrees out of phase (real TWO phase power) The voltage between any hot phase and neutral is 120VAC (sometimes called "110"). When you measure across the two hot legs you get 220-240VAC since one is moving positive while the other is moving negative and the difference is the sum. Probably more than you wanted to know. European AC is a single leg of 220-240VAC and only has one hot wire. No way to get 120VAC without a stepdown transformer.

The chassis of your unit needs to be tied to safety ground (earth ground at the breaker box). Neutral is supposed to be bonded to earth ground at the main breaker but NEVER tie neutral to the chassis of connected electronics. If the neutral ground has been compromised the voltage between neutral and a real earth ground could cause a nasty shock.
\
TOM Caudle
www.CandCNC.com

[Al_The_Man]

The 120/240 in N.A. is still single phase power, not two phase.
In UK the ground and neutral were never connected at the incoming service point, in fact even if the service carried a ground, it could not be used as a system ground, a proper ground conductor had to be used (metal water supply etc) if this was not adequate an Earth Leakage trip had to be installed at the service entry.
The neutral circuit was grounded at the service transformer star point ONLY.
At least this was the case when I worked in the electrical industry in UK.
In N.A. If fitting a 240v to 120v isolation transformer it is customary to set up a local grounded neutral as the original neutral/ground has been lost due to isolation.
This is done by grounding one side of the secondary directly to chassis ground at the transformer and where the service ground enters the enclosure.
Al.

[MRM RCModels]

Originally Posted by TOTALLYRC It is also used on both my CNC mill and soon to be CNC lathe so I know it works. Thanks for the backup Gerry. Always nice to know I got it right. Mike

Thank you very much everyone. I'll be the one running the 220V conduit and didn't want to run another 115V to the other side of the shop (where there's no power). This will save me a lot of time.

CNCZone rocks!

[Torchhead]

Originally Posted by Al_The_Man The 120/240 in N.A. is still single phase power, not two phase. Al.

Ever looked at the waveform on a dual trace scope? It's two legs of 120VAC that are 180 deg out of phase. True, it's single phase going into the pole transformer in most residential locations, and the center tap of the secondary sets the neutral leg. The term two phase is not used (more commonly it's "split phase") probably because it's confusing, but electrically it's two phases of AC with neutral to ground as common. Any transformer can be designed to give opposite phases of AC out. I guess it's the term "phase" that makes it confusing. To me phase describes the waveform based on times (when) it crosses neutral (0 volts). In North America it crosses every 8ms. Phasing is relative. It's described in degrees of difference. (vector descriptions).

Sorry, but I approach electricity as an engineer and I have to take into account the characteristics of the wave forms involved which includes the relative phase of more than one source to a common return. 3 phase has a different characteristic than single or two phase waveforms and cannot be generated/created from single phase with a transformer (sadly).

TOM Caudle
(Old burned-out EE )

[Al_The_Man]

I was always taught to use the terms to describe a centre tapped secondary of a single phase transformer as is described in Wikipedia

Three-wire, 120/240 volt single phase power used in the USA and Canada is sometimes incorrectly called "two-phase". The proper term is split phase or 3-wire single-phase.

http://en.wikipedia.org/wiki/Two-phase_electric_power
Al.