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Need help choosing VFD or RPC for Sharp 1118h

AK-John

Plastic
Joined
Jan 21, 2024
Hey! New guy here! I am very new to having this commercial 3phase machinery in my home shop and I want to make the best choice for this setup. I cant seem to determine the current draw for this particular motor in this lathe. It says its a 5HP 220/440V motor. On the tag it doesnt have a FLA rating but just a stamp that says AMP and 6.5. How do I determine which size VFD to go with for the single phase to 3 phase conversion and then How many amp service do I need to plan for? Will a VFD provide for all of the electrical needs of the lathe? Im hoping a VFD will give me everything I need as its a bit more affordable and takes up less real estate but if its going to make operations more difficult, Ill start the hunt for the RPC.
Thanks in advance. Summary: Need size requirements for VFD and service for sharp 1118h on 220 single phase to 3 phase.
 
I see it also has a half HP carriage feed motor and a lower power coolant pump motor. Does the installation manual or operators manual provide any guidance on powering the lathe?
 
It does indeed have those added motors. Ive downloaded and read the Operators manual and did not see any info regarding the powering of the lathe. Ill look around and see if I can find an Installation manual. Am I safe to assume that I would need multiple VFD's...ie one for each motor? Sounds like a rotary phase converter may be my only option. Thanks!
 
I think because you have multiple motors you're going to want to go rotary phase converter or phase perfect.

This one would likely be ideal:


Without seeing the data plate amp draw it's hard to say for sure. Size the phase perfect for the amp required in the manual.

You can always go up a size for a couple hundred bucks if you're concerned. But in general you're never going to pull FLA on a machine like this.
 
Thank you for your help! That's exactly what Im looking for! If I use the PhasePerfect, it will run everything on the machine just as if it were plugged into commercial 3 phase? Here is whats on the data plate...tried to upload a pic but apparently all of my pics are too large.
Phase-3
KW-.75
Volt 220
Cycle 60
Amp 4.5
Rpm 1720
Design Nema B
Code F
Bearing 6306

Any info after reading the specs would be greatly appreciated. I also see that the PhasePerfect is rated at 31 amps input...would I use a 30 amp double
Pole breaker or step up to 50? Thanks again!

AK-John
 
I don't want to give electric advice over a forum without seeing all the variables so I'll speak in generics.

I would expect a 5hp 3 phase motor to pull closer to 15 amps FLA at 230V 3 phase. So you saying it says 4.5 amps is confusing to me. Also .75kw is only 1hp so I'm worried you're looking at the wrong data plate.

The PP is rated for 18 amps output which is in line with what I would expect a 5hp lathe to require.

You will never actually take a 5hp cut with that lathe (you'll overwhelm your tooling or workholding before the spindle motor). So expect real amp draw to be closer to ~5-10amps other than startup.

The 5HP PP says 31amps max input. You can use a 30amp breaker as long as you size your wires for the 30 amp breaker. The breaker is there to protect the wires. If you wanted to go overkill you could do 40 amp breaker and 40 amp rated wiring to the PP. I'm assuming short run so going a little big on wiring will be a small price difference and is nicer on the equipment (less voltage drop). But it really doesn't matter as long as the breaker and wires are sized as a system.
 
Also to answer your other question the PP will supply 3phase power to the main power input to the machine. Then the machine will have it's own distribution system. It'll be like hooking up the machine to real 3 phase power. It'll work as designed without any fooling around.
 
Phase Perfect is a plug and play option, essentially passes through L1 and L2 and generates L3. The output is 18A three phase, the input single phase is X1.7 and typically X1.25 for VFD drive, the recommended single phase breaker for the 5 Hp 230VAC Phase Perfects is 55A, probably fine to use either a 50 or 60A single phase 240VAC breaker as the lathe will not be pulling FLA for any sustained period of time. The Sharp 118h (at least the newer versions) use VFD drive for he main motor as well as the carriage drive motor, the coolant motor is is listed as 0.25Hp. If you have the VFD model, the motor is usually a vector type and oversized to cover a very wide speed range, basically the amount of power you will be using at any point in time is probably going to be less than the rated full output. So a 5 Hp Phase Perfect should be OK to drive the main motor and ancillary motors. I did not see any input amp rating for this Sharp model, but I routinely run similar 5 Hp lathes off of 50A breakers W/O any issues. If you plan to use other 3 phase machinery at the same time, then you would want a larger rated 3 phase power source.
 
I don't want to give electric advice over a forum without seeing all the variables so I'll speak in generics.

I would expect a 5hp 3 phase motor to pull closer to 15 amps FLA at 230V 3 phase. So you saying it says 4.5 amps is confusing to me. Also .75kw is only 1hp so I'm worried you're looking at the wrong data plate.

The PP is rated for 18 amps output which is in line with what I would expect a 5hp lathe to require.

You will never actually take a 5hp cut with that lathe (you'll overwhelm your tooling or workholding before the spindle motor). So expect real amp draw to be closer to ~5-10amps other than startup.

The 5HP PP says 31amps max input. You can use a 30amp breaker as long as you size your wires for the 30 amp breaker. The breaker is there to protect the wires. If you wanted to go overkill you could do 40 amp breaker and 40 amp rated wiring to the PP. I'm assuming short run so going a little big on wiring will be a small price difference and is nicer on the equipment (less voltage drop). But it really doesn't matter as long as the breaker and wires are sized as a system.
If you have an email or can tell me how to post the picture of the data plate, Id feel alot better having someone actually see what Im looking at. This is the data plate on the main large motor inside that drives the belt to the lathe spindle. Thank you again for your input. I definitely appreciate it!
 
Phase Perfect is a plug and play option, essentially passes through L1 and L2 and generates L3. The output is 18A three phase, the input single phase is X1.7 and typically X1.25 for VFD drive, the recommended single phase breaker for the 5 Hp 230VAC Phase Perfects is 55A, probably fine to use either a 50 or 60A single phase 240VAC breaker as the lathe will not be pulling FLA for any sustained period of time. The Sharp 118h (at least the newer versions) use VFD drive for he main motor as well as the carriage drive motor, the coolant motor is is listed as 0.25Hp. If you have the VFD model, the motor is usually a vector type and oversized to cover a very wide speed range, basically the amount of power you will be using at any point in time is probably going to be less than the rated full output. So a 5 Hp Phase Perfect should be OK to drive the main motor and ancillary motors. I did not see any input amp rating for this Sharp model, but I routinely run similar 5 Hp lathes off of 50A breakers W/O any issues. If you plan to use other 3 phase machinery at the same time, then you would want a larger rated 3 phase power source.
Perfect! Thank you. So I meed ti add a 50A 220v Breaker and wiring to feed the PP and this should run my lathe like normal! Thanks again for your advice!!
 
I would call PT and have them confirm a 5hp Simple Model is appropriate for your machine. Sometimes on stuff with VFD's or multiple motors they might recommend stepping up to an enterprise version. Give them a call and they'll get you sorted out. Then breaker size for the converter they spec is available on the website.


 
Ill start the hunt for the RPC.
Thanks in advance. Summary: Need size requirements for VFD and service for sharp 1118h on 220 single phase to 3 phase.
Getting a quiet RPC is taking a chance if you order something. Most of them have low cost parts.
If you first got a quiet motor yourself then build it yourself. The sellers would like you to believe that they do magic.
A loud idler motor is irritating but you don't have an ignore list for that.
 








 
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