240v single phase to 415v 3 phase conversion

[Oldneweng]

This vfd is rated at 3kw 13 amps. VARIABLE FREQUENCY DRIVE INVERTER VFD 3KW 4HP 13A NEW | eBay

Does this mean that it requires 13 amps to run it and I can plug it into a 15 amp socket? If this is the case then all I need to do is run a dedicated cable from the shed power entrance to a 15 amp socket near the lathe and not run a big heater etc at the same time. The shed has a dedicated circuit and RCD from the main board.

Dean

[jhovel]

Dean,
whatever you decide, here are a couple of fundamentals to help.
A 10hp (7.5kW) motor uses about 7500Watt when it ACTUALLY ptoduces 10hp - and significantly less when it isn't.
Since a 15A powerpoint is likely fused on a 20, 25 or 32A circuit - and cabled with a wiresize to suit that current, as long as the total load on that circuit breaker diesn't go above that, everything is OK and safe. That means you can tun a VFD and motor up to 240Vx20A=4800W=4.8kW, 240Vx32A=7680W=7.68kW or whatever - as a peak actual power used by your tooling on your jobs.
Now, I can't even imagine the chip size a motor producing 10hp in a single point tool in a hobby workshop..... maybe 3/8"x1/8" in mild steel? at a rough guess....
Go and have a look at the circuit breaker you intend to connect the lathe motor to and go from there.
Some of these figures ignore the losses int he motor. So you actually have to look at the current (in Amps) the motor draws to develop the hp advertised.
I run a 5hp single phase motor on my firewood saw bench plugged into a 15A socket. It will draw 30A when I cut 10" dry hardwood logs and have significantly slowed it down by pushing a bit hard. My 32A circuit breaker has never tripped yet and none of the cables or the powerpoint have ever got warm. When not cutting, the mototr draws about 3A. 3-phase motors are much more efficient. My 1.5kW lathe motor draws around 0.6A from the VFD when I'm not actually cutting anything.
Cheers,
Joe

[Oldneweng]

It is a 16 amp circuit breaker. The only difference between 15 amp points and 10 amp points is the size of the earth pin. This is only meant to ensure that you use a proper 15 amp plug / cable to connect to it. The actual wiring behind the points is no different. They may need to be dedicated tho. I will need to check this out.

Dean

[Oldneweng]

I presume you have bigger than standard wire connecting this 15 amp socket then. The circuit breaker is designed to protect the fixed wiring and the buildings around them so you should have at least 32 amp wire connecting it.

Dean

[jhovel]

Sean,
a 16A cuircuit is a standard GPO circuit for 10 powerpoints. You can have (from memory) 10 off 10A powerpoints on a 16A circuit (I may be wrong and it could be more). A circuit for 15A powerpoints, will start at 20A and go to 32A depending on the number of powerpoints connected to it, and will have 4mm2 up to 6mm2 cable behind it. A 16A circuit only has 2.5mm2 cable. It is entirely pointless to bother with 15A powerpoints or plugs on that circuit. Just use the quoted 3kW VFD with a 10A cable and plug and run a motor rated up to 13A at 240V on it - likely to be around 3hp - or a 4hp motor that will trip the VFD maximum setting of 13A. That leaves you enough power on that circuit to run the lathe light, and that sort of thing.
Cheers,
Joe

[Stustoys]

Ok when I said you could use a smaller VSD on a bigger motor I wasnt thinking of a 5.6kW motor. Now you might have another problem which is the motor maybe 415V delta. I'm going to have to have a think about that... better yet get Ray to have a think about it lol

With a 5.36kW 415V motor running on 240V would only be a 3.3kW motor anyway.... I think.

I thought 15amp powerpoints were each meant to have their own breaker?

Stuart

[Oldneweng]

Ok when I said you could use a smaller VSD on a bigger motor I wasnt thinking of a 5.6kW motor. Now you might have another problem which is the motor maybe 415V delta. I'm going to have to have a think about that... better yet get Ray to have a think about it lol

With a 5.36kW 415V motor running on 240V would only be a 3.3kW motor anyway.... I think.

I thought 15amp powerpoints were each meant to have their own breaker?

Stuart

I am no expert and my info is mostly based on SA specs. Long term I hope to upgrade the wiring to the shed. I also read on one of the VSD threads that at about 5hp 3 phase motors tend to be wired in delta anyway so this rules out these motors and bigger for running on 240v 3 phase. This means finding a motor that will suit.

Dean

[Stustoys]

Hi Dean,
I think I've confused you. No problem with running a 415V delta wired motor on a 240V VSD, just you wont get full power.

Stuart

[Oldneweng]

Hi Dean,
I think I've confused you. No problem with running a 415V delta wired motor on a 240V VSD, just you wont get full power.

Stuart

I t wasn't what you wrote that was the problem entirely. It was more what I had read earlier. So if the motor is already wired in delta then it needs 415v for full power but when run on 240v it produces less power. I was reading thru past threads when I saw this info. I read it to mean that it was not possible, at the time and you said "I think" in your post. Anyway a 3.3kw motor would be enough for me I think. Hopefully run this on a 3.0kw VSD set at max of 13 amps and it all should work. Up to a point.

Dean

[Stustoys]

Hi Dean,
Sorry Dean the "I think" was about my maths in the hp reduction(even if the maths is correct the answer likely wont be as I assume the motor will become either more or less efficient....lets call it a ball park ). I havent run a 415V delta wired motor on a 240V VSD, but I have run 415V star wired motors on a 240V VSD(at least I assume they are star wired, I havent been inside them).

Stuart

[jhovel]

Stuart,
I just checked my wiring rules (Not certain that they are the latest - but they are AS3000). You can have a 15A socket outlet on a 20A RCD protected circuit along with up to 4 10A outlets. A 15A outlet (a double powerpoint is considered a single outlet, oddly) can be installed on its own circuit and protected by up to 25A circuit breaker, depending on the cable section used. You cannot connect more than one 15A outlet (single or double) to a circuit it seems. You were mostly right and I was mostly wrong.....

Joe

PS: in the process of checking, I also came across 20A powerpoints - hadn't come across them before. Unlike the 15A plugs and sockets, they actually DO have bigger power pind and connectors, along with the bigger earth pin of the 15A setup).

[Vernonv]

As we are on a SWER system ...

Am I correct in assuming you actually have 2 x 240V phases (180 deg apart i.e 480V phase to phase) coming into your property?

If so you may have other options - I personally run all my 3 phase gear off a 480V static phase converter. No need to change/rewire motors, no transformers and very cheap to setup.

[Stustoys]

Hi Joe,
Thanks for that. Though I am scratching my head over what use a 15amp plug really is, why you can have a double but not two singles 4 feet apart and how having one 15 + four 10A outlets is ok but not two 15s instead......... still I'm sure they have their reasons(if I had to guess i'd say its likely something to do with the chances of multiple things starting at the same time, but thats just a guess). Happy to take half the "wrongness"

Stuart

[Oldneweng]

Star or delta? I don't know which is which. All I know is that I need to connect my lathe motor up somehow. I found out today that the lathe is mine but a price is being worked out. I have a max price but may do better. This lathe is actually the one that I have mentioned in previous threads that was the replacement for my current lathe at work. Will post a pic in another thread shortly. Work has bought one of these https://www.machineryhouse.com.au/L625D

I took some pics today with a new 16mp camera that just arrived and on looking at the pics noticed something.

Attachment 213920

Attachment 213921

Does this mean what I think it does? 2 speed motor?

The new lathe work bought is far bigger than the my new one but it still only has a 7.5 hp motor.

Dean

Joe. Thanks for the info. I need to check my wiring to the shed but I think it is standard. I need to run another cable of 20 amps or more to connect a 15 amp gpo. I don't suppose you can just add a 16 amp cable and call the two a 32 amp circuit. I already have 16 amp cable. I also need to check the distance and work that into the calc.

[Stustoys]

Hi Dean,

Not the dreaded two speed motor, sure looks like it. But you dont need it(though you could likely keep it if you felt you really need it). Wire it up in low speed and use the VSD get your high speed back.

Though I can't understand the picture

Stuart