3 phase question please help...

[Sal Kurban]

Here is the situation: I have two Italian bandsaws (SCMI 600 and Centauro 700 CL) and both are 3-phase. Decided to buy a 10 HP rotary phase converter and asked an electrician neighbor to wire it. When he saw the machines, he says these cannot be 3-phase because it is indicated on them they are prewired for 220 volts. He said 3 phase cannot be 220 volts. 3 phase can be 208 volts or 480 volts or whatever. Now he says if he wires it, he is worried it would damage the motor(s).

I tried very hard to tell him these are indeed 3 phase machines and in Europe 208 does not exist so they are wired for 220. Can anyone give feedback as to how 220 volts can still be 3-phase?

Thanks,

Sal.

[Todd Burch]

I have 3 machines that are 220VAC 3 phase.

Todd

[Jason Roehl]

Post a pic of the spec plate.

[Jack Wilson50]

I sell HVAC equipment and i can verify that there indeed are 240/3/60 motors.

[Sal Kurban]

Post a pic of the spec plate.

Hi Jason,
The motor plate says explicitly it is "trifase" (three-phase) and the connection cover says "220 volt".
Sal.

[Rod Sheridan]

Here is the situation: I have two Italian bandsaws (SCMI 600 and Centauro 700 CL) and both are 3-phase. Decided to buy a 10 HP rotary phase converter and asked an electrician neighbor to wire it. When he saw the machines, he says these cannot be 3-phase because it is indicated on them they are prewired for 220 volts. He said 3 phase cannot be 220 volts. 3 phase can be 208 volts or 480 volts or whatever. Now he says if he wires it, he is worried it would damage the motor(s).

I tried very hard to tell him these are indeed 3 phase machines and in Europe 208 does not exist so they are wired for 220. Can anyone give feedback as to how 220 volts can still be 3-phase?

Thanks,

Sal.

Sal, you can have any 3 phase voltage you want, there's nothing magical about it.

In Canada we have 208 and 600 as the low voltage 3 phase system.

In Europe it's 380 volts, the USA has 480/240 or 440/220, they're actually the same system. There also is 208V 3 phase in the US, less common than the 480/240 system.

We have some 100V 3 phase equipment from Japan at work.........Not commonly used in NA....................Rod.

[Kevin Nathanson]

I have many 3ph 240v/230v/220v motors in my shop, all hooked up to 208v 3ph power. (actually around 209 on a meter. You know, 208, 209, whatever it takes...)

I haven't been out there today, but as of yesterday, my shop has not blown up, nor opened a hole in the space/time continuum.

Although, come to think of it, there is a pair of gloves missing that I have looked everywhere for.

Hmm....

K

[David Kumm]

I'm sure others can give a better explanation but most motors can operate within about a 10% voltage range. You will see motor badges 208-230, 220,208,200 etc. Since motors like higher voltage the only motors that can potentially have problems are old 200 volt ones as the 230-240 range is a little over the 10%. Some guys have run those without problems but many use a VFD so the output can be adjusted. I'm surprised to hear that concern from an electrician. Dave

[ray hampton]

I am surprise that the companies that manufacture pole transformers can keep up with the different voltage

[John McClanahan]

I have many 3ph 240v/230v/220v motors in my shop, all hooked up to 208v 3ph power. (actually around 209 on a meter. You know, 208, 209, whatever it takes...)

I haven't been out there today, but as of yesterday, my shop has not blown up, nor opened a hole in the space/time continuum.

Although, come to think of it, there is a pair of gloves missing that I have looked everywhere for.

Hmm....

K

Same here. 208V 3ph. where I work. All motors run fine.

Your gloves must be covering up the tape measure that I can't find! :D

[Joseph Tarantino]

.......Your gloves must be covering up the tape measure that I can't find! :D

good one! i needed a chuckle on this dreary, rainy morning.

[Halgeir Wold]

European 3-phase is either 220/230 3-phase delta ( meaning there's no neutral), or 380/400V with neutral and ground.
220 and 380 is the old spec - most of Europe and EU is now 230 and 400, all supposedly within+/- 10%.

[Charles Lent]

While the exact voltage is not really that important for running the motors on 208-240 power, having the correct frequency of power is much more important. Induction type motors (most of the 1/2 hp or larger motors) are frequency dependent as it determines the running speed of the motor. Motors that are designed for European 50 Hz power will run faster than their nameplate rating when connected to 60 Hz power and have less output power. Motors that are designed for 60 Hz power will run slower on 50 Hz power and will over heat quickly. You should check the motor frequency as well as the voltage ratings to be sure they will work properly for you. Buck/boost transformers can be used to slightly increase or decrease the 3 phase voltage level if the electric service voltage level is not correct, however this should only be necessary for voltage critical equipment and it's not usually necessary if only for motor loads.

Charley

[David Kumm]

My understanding is that motors designed for 50 hz actually develop more HP at 60 hz, not less. A 60 hz motor will generally not overheat at 50 hz although it might at lower rpm if the cooling fans run too slow. Many motors are run at varying hz with vfds and within reason there is little chance of failure. Dave

[Jim Galvin]

I think he's used to wiring 3 phase from a commerical power source since I believe 208 volts is derived from a three phase four wire, grounded neutral system and which may be wired either single, (two wire), or three, (three wire), phase,
with 120V. available phase to grounded neutral. If you input voltage 220 you should be ok since the rotary converter will converter the input single phase voltage to same voltage only in three phase. Does the manufacturer show this in their installation instructions? Mine did.

[Michael W. Clark]

I think he's used to wiring 3 phase from a commerical power source since I believe 208 volts is derived from a three phase four wire, grounded neutral system and which may be wired either single, (two wire), or three, (three wire), phase,
with 120V. available phase to grounded neutral. If you input voltage 220 you should be ok since the rotary converter will converter the input single phase voltage to same voltage only in three phase. Does the manufacturer show this in their installation instructions? Mine did.

We had 480V 3ph at work. If you take one leg of it, you have 277V. Most industrial light fixtures use 277V to make installation less expensive. My understanding is the voltage difference is the way it is measured. One way is phase to phase voltage and the other is phase to ground voltage. This is still 3ph power. If you have 3ph and you want 1ph, a small transformer is usually required. This is common when you have a 3ph MCC and you want some 1ph 110v plugs or you have some additional 1ph equipment.

Mike

[Sal Kurban]

I think he's used to wiring 3 phase from a commerical power source since I believe 208 volts is derived from a three phase four wire, grounded neutral system and which may be wired either single, (two wire), or three, (three wire), phase,
with 120V. available phase to grounded neutral. If you input voltage 220 you should be ok since the rotary converter will converter the input single phase voltage to same voltage only in three phase. Does the manufacturer show this in their installation instructions? Mine did.

You are correct, he is used to wiring industrial stuff... I finally convinced him thanks to your comments and he is wiring it tomorrow. The RPC did come with a wiring diagram and he said the wiring is simple enough. He just was worried about damaging my equipment. I will have him check any imbalance in the RPC output before we start any machine.

Thanks to all who clarified the issues.

Sal.