The difference between single and triple phase?

O

OneOneBravo

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Jan 7, 2007
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I am new to this but if I may ask. What is the difference between single and triple phase? I am looking to get a KMG with the best motor sold on the KMG website, the 3HP single phase variable speed model (cat no. VS-VFD-3.0). I have an electrician that lives across the street who says he can put a 220v line in my spare garage. It has 110v now with plenty of space on the breaker box (it has an electric water heater so I wonder if that's 220v). Is there anything I should tell him to do when installing the 220v line? Does the installed line need to be 1 or 3 phase and does a VFD need 3 phase to function optimally? Thank you in advance.
 
Three phase power is not normally available to residential homes. That is why the three phase motor is driven by a VFD. The VFD input takes 220 VAC single phase power and delivers three phase to the motor. By changing the frequency of the power, the VFD allows the motor to run on speeds from stop to very fast with little power loss.
Your electrician simply needs to wire up a 220 socket with a receptacle to match the one on the VFD.
 
bladsmth said:
Three phase power is not normally available to residential homes. That is why the three phase motor is driven by a VFD. The VFD input takes 220 VAC single phase power and delivers three phase to the motor. By changing the frequency of the power, the VFD allows the motor to run on speeds from stop to very fast with little power loss.
Your electrician simply needs to wire up a 220 socket with a receptacle to match the one on the VFD.
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Thank you very much. What type of socket would I need for the KMG 3hp and VFD from BeaumontMetalWorks? I am gonna have my electrician install it in advance.
 
You need to find out how many amps your setup will draw and wire in an outlet for 25% more than that (NEC standard, wiring should only carry 80% of max during normal operation) rounded up to the next standard trade size. This is tricky, as the current listed on the nameplate of the 3 phase motor is NOT the same current the VFD will draw from your single/split phase 220! You need to pick out a VFD that will drive the 3 phase motor and use the full load current at 220V input for that VFD.

3p vs. 1p for dummies: 3 Phase power is like 3 separate 60 Hz (or 50Hz in euro power systems) lines, each offset so that they peak at even intervals (120 degrees offset). The main advantage is that you get 3 peaks per cycle (180 peaks per second at 60 Hz, 150 at 50Hz) with 3 phase instead of one peak with single phase. That gives the motor much better torque and power, and it runs smoother and (usually) cooler. Most of the motors work is done at the peak voltage, so it is a very real advantage...Note that even though US 220V is 2 hot lines, because it only peaks 60 times a second, it is still single phase. True multiphase peaks in multiples of the base frequency.

Confused yet??? I'll stop here unless I get a request for clarification.:p
 
CDH, thanks a lot sir. I will be getting the 3HP 1p motor offered on the KMG website and it is advertised as variable speed. So no need to worry about 3p it looks like. I just wanted to let my electrician know. Do I have to buy a 50amp socket or another type to run the line? Is it possible to have my electrician install 2 or 3 220v sockets to plug multiple tools in. I am thinking about getting a 3hp 1p 220v bandsaw as well. Thanks in advance.
 
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OneOneBravo said:
CDH, thanks a lot sir. I will be getting the 3HP 1p motor offered on the KMG website and it is advertised as variable speed. So no need to worry about 3p it looks like. I just wanted to let my electrician know. Do I have to buy a 50amp socket or another type to run the line? Is it possible to have my electrician install 2 or 3 220v sockets to plug multiple tools in. I am thinking about getting a 3hp 1p 220v bandsaw as well. Thanks in advance.
Click to expand...

You can socket or hard wire the branch. Sockets are nice when you want to move things, but unless you put them all over your garage/shop you will be facing the same issue once again if you rearrange...

I recommend a dedicated circuit for a high current (relatively) device like your KMG motor and bandsaw. If you have several motors to run, then run several lines and you'll be fine. Running several outlets on the same branch is begging for tripped breakers when both are turned on at once. Otherwise you need to size the wiring for all motors combined (max possible load) and it'll get big fast. Copper is fairly pricey these days...but one big run is false economy over several reasonable sized ones.

'Extra' 220V sockets are up to you. They are easy to run if you ahve the space in the panel for breakers, but look around and decide if you'll need them. Maybe a heat treat oven, air compressor, and what else do you see in your future shop?

How big is your service connection (main breaker to the house/garage)? Multiple 50 amp circuits eat up a standard 150 or 200 amp service fast...

Have fun!
 
Thank you very much. I will have to look into most of those questions. I don't see me having multiple tools on at the same time since I will be the only one there. I just want to have all of my tools hooked up and ready when I flip the switch. I figure 220v for the Grinder, kiln (maybe). Drill press and band saw may or may not be 110v. I still have to choose those. My main concern is to buy the right tools the first time and eat the cost up front. If you could suggest some reasonably prices tools, Band saw, Drill press, etc. That would be excellent. I want to have good tools that will last. Thank you ahead of time CDH.
 
OneOneBravo,
The wallet usually dictates what we can purchase for machinery. If you can purchase new, stay with 220v single phase as CDH was pointing you towards. I just went through this within the last two weeks. I wanted but could not afford a new large floor model surface grinder but found one that met my needs which was older but 3 phase.

They make two types of converters, a static phase converter and a rotary phase converter. For my machine the first about $150 the second about $500. I tried the static one first without getting the results I wanted. Phase-A-Matic put together a rotary converter for me helping me all the way with the challenges of hooking up an older machine. Those guys bent over backwards to help me. It now runs like a top.

If you later find yourself in the position of only buying 3 phase, a rotary converter will give you approx. 95% of original power. The machine basically won't know it isn't on 3 phase.

Good luck
Larry
 
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