[Brenck]

Hi all,

I am currently wiring all my machine to 220v. First I got an electrician to make one of my outlets 220v with ground. So I have a 3 pin plug that 2 of them are live and 1 is ground.

I will have the PC, Electronics and VFD on 220v, so this way I have just one wire out of the electronics cabinet. On the control box of my machine I have a main switch that turn on all the box. Inside of it I have steppers PS, a 12v ps for fans and one outlet that is connected to a relay board for turning on a coolant pump.

Since is 220v I needed connect both wires to the switch ( one on each side of thoose red panel switches ) or else I would still have 1 live wire on the circuit, like if I had wire as if it was 110v.

Its ok to do that with the Stepper PS and 12v PS. I'm actually confused about the realy, because the relay its like a switch and it cuts of just one leg of the circuit. What to do with the other live wire?

My relay board is this one: http://arduino-direct.com/sunshop/im...ay-2-1-450.jpg

One of the relays is connected to this outlet that I plug the coolant pump on and the other one is wired to the vfd for turning on the spindle

Do I need anything else? How to wire this?

[Al_The_Man]

If I interpret what you are saying correctly, you will need to cut power to both live conductors?
In the case of 2 live conductors, both conductors should be switched and fused.
In this case you need to ideally set up a low voltage E-stop circuit and use this with a small control relay to switch off the coil to a power relay or contactor in the main supply that switches power to all but the low voltage control and PC. This way all your E-stop circuit is low voltage.
You could use the 12v power supply for this.
Ahead of all this should either be a double pole main disconnect switch, which it sounds like you have, or if close by, you can use the main wall plug and socket.
You can use the small relay on the arduino link to cut the coil power mentioned above.
Al.

[Brenck]

Actually the pc its outside this control box, I will have like inside a cabinet the PC, VFD and this control box, this control box have just the stepper P.S., 12v P.S., relay board and a G540. This box will be wired to a double switch that turns on the main power for the machine ( inverter, pc and this control box etc.. ) this is not the problem.

The big deal its inside the control box with the relay, this box have a double switch, I just have it there so I can turn on and off and test it before I set everything inside a cabinet.

The relay is like a single switch, so it will cut off just one leg of the pump 220v circuit, so I will still have another live wire, Is there a way to cut this live wire as well? Or I will need 2 relays one for each wire? Then I would connect their input to the same pin of the g540 so they would turn on the same time

By the way this control box is powered by a IEC connector with a internal fuse on it ( like this one http://www.sinolec.co.uk/14-59-large/0717-1pq.jpg ), but it only fuses 1 leg. Is that a big deal? Also I have a lower value fuse from the 48vdc stepper PS to the G540 as well as one on the end of the 12v P.S., that to protect the circuit in different ''sections''

[Al_The_Man]

Like I said, you have to fuse and switch both live conductors, the relay you need is a Double Pole Power Relay, you can also use a 3 phase contactor as these can be often picked up cheap in ebay.
This would switch power to the drives and spindle etc.
Al.

[Brenck]

I currently have a 10a fuse on that IEC, I will add a wire fuse holder to the side that doesn't have a fuse, after that do I change to 2 5a fuse fuses or I keep 10a on each phase?

Thank you for all the help

[Al_The_Man]

You need to calculate the total load, you also have a VFD to take into account the HP for that.
Fitting a suitably rated double pole relay or contactor will can switch the VFD in the E-stop condition.
Al.

[wildwestpat]

Simple the current flows in at one pin and out at the other so both fuses would be the same rating. Check this is your wall socket as illustrated below. If so the cord used to connect the case to the wall socket should be 10 amps and the fuses are similar.

You should verify that your supply is connected so that although you have one earth pin that the other two are live and neutral NOT 110 - 0 - 110 with respect to the earth pin. As far as I am aware you do not have this type of supply in the towns. If this is so then one fuse is OK provided it is in the brown lead often marked L. That is because the blue wire is the neutral and is only a few volts above earth potential. The brown or live is the full supply voltage with respect to earth.

However IMHO because even when the neutral is near ground (earth) voltage it can still give a nasty nip under some fault conditions I would switch both the blue and the brown wires and ensure all wiring between the inlet (IEC). Make sure the isolating switch protected so that your fingers or stray wires cannot make contact with the mains input to the box during repairs or adjustments. There are IEC plastic boots for the sockets and perspex plates on pillars are another possible protection. Mains voltage relays and contactors are available with shrouded terminals.

Just keep the rating of the cord to the socket as the maximum for the fuse. I note you have various circuits in your box so check the fuse rating and type. There are glass cased fuses that are quick blow and these can cause problems - use slow blow anti surge or ceramic cased ones. Also be aware that there are various moulded cord sets with IEC ends that have different current ratings.

Hope this helps - regards - Pat

[Brenck]

I mean do I need to divide the fuse amps? since I am using one fuse on each live leg. Lets say total load will be 2000w on 220v and I need a 10a fuse, is it 2 10a fuses or one 5a fuse on each leg?

[Al_The_Man]

10 amps in each, I understood from your first post you do not have a neutral, you mentioned having two live conductors, the same as N.A.?
Because you never switch or fuse a neutral.
Al.

[Brenck]

Simple the current flows in at one pin and out at the other so both fuses would be the same rating. Check this is your wall socket as illustrated. If so the cord used to connect the case to the wall socket should be 10 amps and the fuses are similar.

One fuse is OK provided it is in the brown lead often marked L. That is because the blue wire is the neutral and is only a few volts above earth potential. The brown or live is the full supply voltage with respect to earth. However as the neutral can still give a nasty nip under some fault conditions I would switch both the blue and the brown wires and ensure all wiring between the inlet (IEC) and the isolating switch is insulated and both switch and input socket inside the 'Box' are covered to prevent accidental contact during repairs or adjustments. There are IEC plastic boots for the sockets and perspex plates on pillars are another possible protection. Mains voltage relays and contactors are available with shrouded terminals.

Hope this helps - regards - Pat

The Blue its always neutral, but here its like US when you wire 220v you have 2 live and no neutral so together you will get the 220v. So in my case there is no neutral so I believe I need to fuse both like Al said.

In my breaker board I get 3 127v lines one neutral and one ground I believe in the US is the same

[wildwestpat]

Hi Brenck As a matter of safety the input to your CNC box should be fully isolated by a suitable double pole switch if you are not going to unplug from the wall socket. To prevent accidental contact with mains live terminals any terminals that remain connected to the supply with the switch in the 'OFF' position should be fully insulated. During testing a lamp wired temporally across the equipment side of the isolating switch serves as a reminder to switch 'OFF'.

If you are going to use a relay as the isolating switch that should be rated as an isolator for 220 volts as well as current make and break current.

I use protective covers over just the mains input and isolator switch or use insulating boots that cover the terminals if they are of the exposed type or put all the hot mains stuff in a separate compartment

As to the need for one or two fuses which both need to be the same current rating a simple check is to look at the fuses or breakers in your main fuse box near the supply companies meter. In Brazil you have more than 25 electricity supply areas and the country has embarked on conversion to 220v using the sockets described the PDF file attached to my last post. The fuses box that supplies all the electricity to your property will have the sockets wired to either one or two fuses per circuit. If your main fuse board adjacent to the meter has breakers these might be single or double pole and telling how many poles becomes more complicated.

Further clues are provided by the fuse where it joins the incoming supply cable from either the over head line or underground cable if you have 110 - 0 - 110 supply then there will be two fuses - if there is only one then it is 220 live and neutral in which case do not fuse the neutral. The risk with 220 volt L&N supplies is reversal of the terminals. and on some equipment there is a neon pilot light wired between the earth pin and neutral to indicate either reversed terminal connections or a gross supply fault. The neon pilot bulb require in excess of around 90 volts to strike and has a current limiting resistor that limits the current to a value which will not trip and leakage breakers in use. Most electricians will also carry a simple test plug that verifies the correct connection of L&N as well as the presence of and earth connection. Further test equipment is required to measure insulation and current carrying capacity in terms of conductor resistance of all three wires back to the fuse box but these tests require a competent electrician as well as specialised test instruments.


Regards - Pat

[Brenck]

I figure it out what I will do. I will have like a main electric box inside the cabinet that will have a main switch ( double pole ) to turn on all the electric for the machine, inside the cabinet it will turn on VFD, PC ( I will make something to make the power button stay on all the time ) and the control box.

I won't use a double pole relay on the control box because I will have to change a lot of things inside to do that.

Instead I will have a switch on the cabinet box so if it is opened the main switch will turn off and with this no electricity arrives at any of the electronic components. Like the ones present on the gear cover of lathes, if the cover its off it doesn't turn on the lathe.

Thank you all for the help

[Al_The_Man]

By that it sounds like you are not implementing an E-stop circuit? If so that is not really a good idea.
I know this is not a commercial machine, but the code pretty much everywhere insist on it.
I am not sure what you mean by 'make something to keep the power button on all the time'?
Al.

[Brenck]

I will have the e-stop of the g540 so that will stop the machine.

I will still have a switch to turn on the entire machine/cabinet/eletronics and with the switch on the door of the cabinet cutting off the main power when the door its open I believe there is no way that someone will get shock, even that the machine stays connected to the outlet at all time

Make something to keep the PC button on all the time, like when I turn on the machine the pc will start right away without needing to press the power button. This way I can keep the pc inside the cabinet with closed doors and just the monitor visible.

Running out of the subject real quick, is there a problem to run the G540 with just 3 motors connected to it or is there something special that I need to do?

[Al_The_Man]

I will have the e-stop of the g540 so that will stop the machine.

Technically that is not the correct way to institute an E-stop but I suspect not all that many do it the proper way anyway.

Running out of the subject real quick, is there a problem to run the G540 with just 3 motors connected to it or is there something special that I need to do?

Doesn't appear you have to?

Al.

[Brenck]

Al,

I have another question, I have the 48vdc and 12vdc P.S. inside the control box. I have all the negative vdc of the box wired together ( I think you say this is the common )

Is it the same as if it was on a 110v circuit that you wire the VDC negatives ( common or idk ) to the physical ground ( the green wire that goes in the metal structures and the chassis box, the 3rd wire of the outlet ). So basically I will connect the green wire from the outlet to the black ones that are used for the - on the vdc side of the P.S?

I get confused on the terminology of negative, ground, common, neutral and earth most of it because in portuguese ground and earth have the same meanings and here the ''ground'' is the green wire that its wired to that copper bar buried to the ground soil for protection, the third pin of the outlets, and earth means the same to... Thats why I have the ( ...... ) to explain it what I am thinking

[Al_The_Man]

Personally I subscribe to Earth Grounding the various supplies, your PC P.S. common is most likely already at earth grounded through the case.
All earth grounds should go to a central Earth Ground plate together with your service ground conductor.
Also any earth bonding conductors should go to this plate.
E. Ground should not be used as a conductor.
Unfortunately now the term Ground is used rather indiscriminately for not only earth ground but all system commons.
I much prefer the old method where the term common was used together with the identity of the supply it was allied to, for e.g. 5v common, 12vcommon etc.
And Ground usually referred to actual earth ground.
There is a lot less confusion that way.
Al.

[Brenck]

Ok with the terms then.

So will I get ground loops if inside the control box I connect the common of my Stepper 48v P.S. and 12v P.S. and to the case together to service ground if my PC P.S. common is already grounded? Im sure my dell pc have the common of its P.S. connected to its ground

[Al_The_Man]

If you use the One point grounding system and ensure all bonding conductors go to this point then you should not have ground loops.
This occurs when a potential is present between one grounded point and another.
This can occur where a PC is used external to the machine and plugged into a wall socket, there can then be a potential between the PC ground and the machine ground which would getting its service ground from another point.
http://www.automation.siemens.com/do.../emv_r.pdf?p=1
Al.

[Brenck]

I have read this siemens .pdf while searching grounding questions. So I believe it will not be possible that I have ground loops on my system considering the entire machine/system/computer/cabine will be connected just with one cable the outlet. And the base of the cabinet will have rubber feet

You must be tired of answering all this grounding questions, I noticed that you are on all threads that I searched and read about the subject. Sorry for asking another one