[thisispete]

I'm building DIY electronics for a 4x4 table.

I have
- 220v hy VFD
- power supply that was wired for 110v (but has no specs so I don't know if it will take 220v)
- Gecko 540

I want to have a main power switch to the enclosure

Is it common to run 2 separate power cables, one 220 for the VFD and one 110 for the control board, and switch them individually?

OR

If I have 4 wire 220 running into the enclosure (hot - hot - neutral - ground) can I switch the 2 hots using a DPST switch and pull 110v from one leg of the hot and the neutral?

(See attached sketch)

[Jim Dawson]

It's acceptable to use the 4 wire system. That's how 120V is derived in the breaker panel.

[Al_The_Man]

You should also wire in suitable fusing in each of the the entry power conductors continuing to each of the destinations.
Al..

[mactec54]

I'm building DIY electronics for a 4x4 table.

I have
- 220v hy VFD
- power supply that was wired for 110v (but has no specs so I don't know if it will take 220v)
- Gecko 540

I want to have a main power switch to the enclosure

Is it common to run 2 separate power cables, one 220 for the VFD and one 110 for the control board, and switch them individually?

OR

If I have 4 wire 220 running into the enclosure (hot - hot - neutral - ground) can I switch the 2 hots using a DPST switch and pull 110v from one leg of the hot and the neutral?

(See attached sketch)

Your sketch is correct just add circuit breakers or fuses for each device

You need to avoid running from to separate sources

[BrokenHorn]

Your sketch is correct just add circuit breakers or fuses for each device

You need to avoid running from to separate sources

Just out of curiosity, why avoid running your 220V and 110V from separate sources?

I read the opposite previously. It said to power your 110V from a separate source since using one leg of your 220V could cause an imbalance that the VFD wouldn’t like.


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[Jim Dawson]

Just out of curiosity, why avoid running your 220V and 110V from separate sources?

I read the opposite previously. It said to power your 110V from a separate source since using one leg of your 220V could cause an imbalance that the VFD wouldn’t like.


Sent from my iPhone using Tapatalk

If the wire sizes are spec'd for the load, there would be no significant voltage sag. There can be no imbalance on a 240V single phase circuit, since the voltage is measured across the two ''hot'' legs. There could be an imbalance between the hots and the neutral, but the VFD doesn't ''see'' that because the neutral is not connected to the VFD.

[BrokenHorn]

If the wire sizes are spec'd for the load, there would be no significant voltage sag. There can be no imbalance on a 240V single phase circuit, since the voltage is measured across the two ''hot'' legs. There could be an imbalance between the hots and the neutral, but the VFD doesn't ''see'' that because the neutral is not connected to the VFD.

Thanks for the clarification. So having more amp draw on one of your “hot” legs (the one going to neutral for your 110V components) won’t be an issue then? I think that’s what the other post meant by imbalance (more amp draw on one hot leg versus the other).

If it’s already set up with the 110V components getting power from a different circuit than the 220V components there’s no harm in keeping it that way is there?



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[Jim Dawson]

Thanks for the clarification. So having more amp draw on one of your “hot” legs (the one going to neutral for your 110V components) won’t be an issue then? I think that’s what the other post meant by imbalance (more amp draw on one hot leg versus the other).

If it’s already set up with the 110V components getting power from a different circuit than the 220V components there’s no harm in keeping it that way is there?



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As long as it's working OK there is no reason to make a change, especially in the home shop. In an industrial application I would install a 240/120 control transformer to power up needed 120V stuff, this is to provide a single point disconnect for the entire system for safety reasons.

There are some advantages to running a seperate circuit for the 120V stuff. On my lathe for instance, the 3 phase comes off of the RPC, which supplies the drive power and 120V control voltage from a transformer. But the computer and 24V control power is supplied by a separate 120V source so the computer can be powered up without running the RPC

[thisispete]

If it’s already set up with the 110V components getting power from a different circuit than the 220V components there’s no harm in keeping it that way is there?

Broken horn - correct my understanding is that as long as the dc control circuit for the vfd is properly isolated then there is no issue running separate sources.

What I'm a little unclear about is grounding between AC and DC, a friend offline said not to "ground" the DC to the AC circuits. So the one that says "gnd" from the 540 to vcd should really be vdc- under the hood, and shouldn't use the real earth ground from the vfd. they probably labeled it gnd because its an isolated 10v signal circuit and not the 40vdc that the gecko runs on.

[thisispete]

Thanks everyone for your responses.

I have a better understanding now.
Learned that my 40v power supply actually has a 115 / 230 switch!

[Jim Dawson]

Broken horn - correct my understanding is that as long as the dc control circuit for the vfd is properly isolated then there is no issue running separate sources.

What I'm a little unclear about is grounding between AC and DC, a friend offline said not to "ground" the DC to the AC circuits. So the one that says "gnd" from the 540 to vcd should really be vdc- under the hood, and shouldn't use the real earth ground from the vfd. they probably labeled it gnd because its an isolated 10v signal circuit and not the 40vdc that the gecko runs on.

I have done it both ways with no problems. But if all of the grounds are connected together, they must be tied to a single point to prevent ground loops and possible imbalances in the ground circuit. The DC- in most industrial systems is earth grounded.

Thanks everyone for your responses.

I have a better understanding now.
Learned that my 40v power supply actually has a 115 / 230 switch!

That being the case, I would connect to 230V and not bring in the neutral unless you need it for something else.

[Al_The_Man]

Broken horn - correct my understanding is that as long as the dc control circuit for the vfd is properly isolated then there is no issue running separate sources.

What I'm a little unclear about is grounding between AC and DC, a friend offline said not to "ground" the DC to the AC circuits. So the one that says "gnd" from the 540 to vcd should really be vdc- under the hood, and shouldn't use the real earth ground from the vfd. they probably labeled it gnd because its an isolated 10v signal circuit and not the 40vdc that the gecko runs on.

You should have one earth ground reference point, commonly known as the Star point ground, this is where the service ground and all shields etc should be connected to, there is two schools of thought over whether to reference any DC supply commons to this earth star point, one to leave every thing separate, and the second to reference all DC commons to this point where electrically possible.
I subscribe to the latter.
If you search here in the Forum, you will find a few posts where those having spurious noise issues have been cured on a suggestion of mine to ground these DC commons etc.
I have used this philosophy for many decades with no problem.
Al.

[mactec54]

Just out of curiosity, why avoid running your 220V and 110V from separate sources?

I read the opposite previously. It said to power your 110V from a separate source since using one leg of your 220V could cause an imbalance that the VFD wouldn’t like.


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One of the main problems is a Ground loop, when you use 2 different sources for supplying one control cabinet, an imbalance is quite hard to achieve if everything is wired how it should be

This can be done only if you have a single point Ground source, if you don't do it like this then you will have a Ground loop

[wizard]

I'm a little late to this conversation but might be able to add a few points.

General in industry you want one disconnect per machine. That can become to hard to define if you have a work cell of connected machines but one of the drivers is to ease OSHA compliance and National Electrical code compliance. This especially in the case of electrical lock out and tag out procedures. It is also not considered good practice to mix power sources in a machine.

Thanks for the clarification. So having more amp draw on one of your “hot” legs (the one going to neutral for your 110V components) won’t be an issue then?

Well one amp isn't likely to be an issue! You could have an issue if one leg ends up with a current draw that causes the breaker to trip. In an ideal situation you would keep your 110 loads balanced just like you would in an electrical distribution panel box (breaker box). Also in many cases you can simply use power supplies that are designed to run off 220 VAC. Frankly with the advent of switching power supplies there are many power supplies that are already able to run off 220 VAC.

I think that’s what the other post meant by imbalance (more amp draw on one hot leg versus the other).

A huge imbalance would be bad but there is no reason for that to happen in a home built control panel. You have two ways ot control the imbalance, one is to use 220 VAC devices. The other is to pay attention to how you load the two legs with 110 VAC devices.

If it’s already set up with the 110V components getting power from a different circuit than the 220V components there’s no harm in keeping it that way is there?

I would most certainly not do that! You are far better off with a carefully constructed panel box that is supplied for one AC drop. The AC drop of course has to be sized properly.

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As an aside the panel boxes built for most routers are extremely simple compared to what might be seen in a large industrial machine. When you have machines with multiple derived power supplies you run into situation where a maintenance or upgrade wiring mistake can raise havoc. This can lead to short circuits, blown subsystems and so forth. In a DIY router you can escape most of these problems by keeping the low voltage hardware separated from the high voltage and following industry standard wiring protocols. That includes color coded wiring and proper marking of wires.

In the case of 220 VAC single phase that means marking the legs and avoiding mixing them up. It also means keeping track of neutral wiring. The white (neutral) wires should be marked and paired with each fused 110 VAC branch you create. This is especially important when the feeder might be rated for more that 15 amps and you want to save money on wiring to lower current devices.

Frankly the processes here are not any different than what is seen in a electrical breaker box, your neutrals have to be suitable for the branch circuit you create. If this isn't clear, not the greatest writer I must admit, you should seriously consider taking a home wiring course if any are offered by local education institutions. At least the well done courses can pay off with a life time of savings around the home.

[Al_The_Man]

You should seriously consider taking a home wiring course if any are offered by local education institutions. At least the well done courses can pay off with a life time of savings around the home.

Also NFPA79 (Electrical Standard for Industrial Machinery) is a great asset, I believe there is a PDF copy out there via Google.
Al.

[mactec54]

I'm a little late to this conversation but might be able to add a few points.

General in industry you want one disconnect per machine. That can become to hard to define if you have a work cell of connected machines but one of the drivers is to ease OSHA compliance and National Electrical code compliance. This especially in the case of electrical lock out and tag out procedures. It is also not considered good practice to mix power sources in a machine.


Well one amp isn't likely to be an issue! You could have an issue if one leg ends up with a current draw that causes the breaker to trip. In an ideal situation you would keep your 110 loads balanced just like you would in an electrical distribution panel box (breaker box). Also in many cases you can simply use power supplies that are designed to run off 220 VAC. Frankly with the advent of switching power supplies there are many power supplies that are already able to run off 220 VAC.

A huge imbalance would be bad but there is no reason for that to happen in a home built control panel. You have two ways ot control the imbalance, one is to use 220 VAC devices. The other is to pay attention to how you load the two legs with 110 VAC devices.

I would most certainly not do that! You are far better off with a carefully constructed panel box that is supplied for one AC drop. The AC drop of course has to be sized properly.


As an aside the panel boxes built for most routers are extremely simple compared to what might be seen in a large industrial machine. When you have machines with multiple derived power supplies you run into situation where a maintenance or upgrade wiring mistake can raise havoc. This can lead to short circuits, blown subsystems and so forth. In a DIY router you can escape most of these problems by keeping the low voltage hardware separated from the high voltage and following industry standard wiring protocols. That includes color coded wiring and proper marking of wires.

In the case of 220 VAC single phase that means marking the legs and avoiding mixing them up. It also means keeping track of neutral wiring. The white (neutral) wires should be marked and paired with each fused 110 VAC branch you create. This is especially important when the feeder might be rated for more that 15 amps and you want to save money on wiring to lower current devices.

Frankly the processes here are not any different than what is seen in a electrical breaker box, your neutrals have to be suitable for the branch circuit you create. If this isn't clear, not the greatest writer I must admit, you should seriously consider taking a home wiring course if any are offered by local education institutions. At least the well done courses can pay off with a life time of savings around the home.

You are right in most cases, the most important thing you where talking about you got wrong voltage NA voltage has been 120v/240v since the 60s

And nobody should worry about imbalance, it is almost none existent in a hobby built system

[TTalma]

It sounds like you have the issue solved being able to run your PS on the 220V.

For future reference or anyone else reading this. You need -> hot - hot - neutral - ground.

Your breaker should be for 220V, and sized appropriately. I.E. if your 220V system uses 30 Amps and your 110V uses 10 Amps, you need a 40 Amp breaker in the panel. But to be safe you should be running your power local in the machine with a 30 Amp 220V breaker and a 10 Amp 110V breaker.

[Al_The_Man]

It sounds like you have the issue solved being able to run your PS on the 220V.

Incidentally the vast majority of N.A. is now 240v, 120v-0-120v.
Assuming the OP is N.A..
Al.