I have 3phase in my shop. I have a new machine that is rated for 208v 3ph. how can I tell what my incoming voltage is?

Here's the link, check page 27 for right voltage connection.
http://www.millerwelds.com/om/o223aw_mil.pdf

1. Why not buy a phase loss monitor that monitors all 3 legs. 208v 3ph is 115-120V to neutral. If you're using two 120V relays you'd only be monitoring 2 legs of the 3 phase. Using relays can be risky, as sometimes when you loose one phase you'll still pick up voltage through your load. If your set on using relays use 2-208V relays. Connect one to phase A+B and the other to B+A and then wire two of the normally open contacts in series and put that in your circuit with your pressure switch. I'f you're using 208V for control voltage, then you need to take L2 to the oveloads and then to the coil. L1 would go to your pressure switch, and the return from the pressure switch would go to the other side of your coil. You could add your phase loss protection here.

Check the voltage at the outlet. It should be 208v or 240v. check by putting meter probe into the 2/3 slots. NOT the U shaped,or round looking holes.Check one to another. Check tag on range for voltage of range. If you have 208v at the outlet and range is 240v the oven will take forever to heat, it is not getting the power it needs. If the tag says 230v either will work. On the oven tag it will say either 1ph, or 3ph. If it says 3ph you outlet should have the voltage mentioned above between ALL 3 SLOTS! If you get 120v when testing any slot, you have only 1ph of power. Keeping it simple, the ph, (or phase,) between the outlet and oven have to be the same.

install 30 amps 3phase breaker, then wire it up with royal cable 5.5mm x 4wires

Your question is a bit unclear, but I assume you are asking how to wire the pressure switch in a piston compressor.

See the diagram, below.

You should have a wire from the L1 (first incoming main voltage) terminal to the pressure switch, and from the other pressure switch terminal back to the starter coil. You will also have a wire from L2 (second main voltage terminal) to the overload, and from the other overload terminal to the other side of the coil. In this arrangement, the motor starter coil must be rated at the SAME VOLTAGE as your incoming power.

This diagram works the same for single phase machines (they just don't have the third wire coming from the supply through the starter and overload to the motor.

If your machine has other safety controls (like a low oil switch), It can be wired in series with either the pressure switch or the overload.

Your question is a bit unclear, but I assume you are asking how to wire the pressure switch in a piston compressor.

See the diagram, below.

You should have a wire from the L1 (first incoming main voltage) terminal to the pressure switch, and from the other pressure switch terminal back to the starter coil. You will also have a wire from L2 (second main voltage terminal) to the overload, and from the other overload terminal to the other side of the coil. In this arrangement, the motor starter coil must be rated at the SAME VOLTAGE as your incoming power.

This diagram works the same for single phase machines (they just don't have the third wire coming from the supply through the starter and overload to the motor.

If your machine has other safety controls (like a low oil switch), It can be wired in series with either the pressure switch or the overload.

I need to know the Power rating Example 5Kw or the Ampere Ex. 30A . What is the raring of each oven? The Breaker should be greater than the Ampere of your oven let say 120% greater.

hi,
u can change the 3phase heater to single phase.apart from all the component are of 1 phase.but consumption of current will be mre.apart from machine will run normally.

Hello. If the unit is rated 460v, 3phase, the only way you can get it to meet your supply of 208v, 3phase, is:
a) have a transformer installed to make 460 from your supply by an electrician, or call your power company and see if 460 could be supplied to your building, but it would only be for that machine.
or
b) replace the heating elements for the 208v supply, have the pump motor checked to see if it will work on 208v, and a control transformer for the control circuit, as well as all the wiring related to the pump and heaters, as on 208v, they will draw more current than on 460.
so, can it be done? yes. Is the expense worth it? only you can answer that, However I would suggest that you resell that machine, and get the correct one from the start.

Hope that helps, and thank you.

The dryer should work ok on 208 volts. The drying time may be a bit longer than usual since at 208 volts, you will only have 5408 watts of heat. Your bigger problem is your three phase panel. You can hook up one "hot wire" from the dryer to any of the three 3phase wires, and the other "hot wire" from the dryer to either of the two remaining 3phase connections and you will have a good connection to your dryer. However, the third wire from the dryer is a "ground wire" which has no connection in the three phase panel, or at least you didn't say it has one. If you can pull a ground wire from the grounding lug of the service panel feeding your 3phase box, and connect it to the third wire on the dryer, you would have a safe connection.

At 208v, the dryer will pull 26 amps. Be careful and make the right connections.