24 replies to this topic

[TOERUNNER]

Hi guys has anyone done this conversion. The existing 3 phase motor does 2700 rpm compared to 1440 rpm that the 240v one from molnar does. I am a bit concerned that it may be painfully slow. Thoughts please.

[yel327]

Ask Molnar. They are an Aussie Company. Not sure whether mine is a 2 pole or 4 pole motor, just ran a 3 phase supply to it.

Edited by yel327, 15 July 2020 - 05:04 PM.

[yel327]

I just checked my 3 phase one, it’s a 2 pole (2700rpm).

A 2.2kW (3hp) single phase motor will almost be too big for a 15A outlet, they draw around 14.5A. Possibly they sell a 4 pole one as it uses a bit less current than a 2 pole so you can run it on a 15A outlet. Don’t try it on a 10S outlet, it’ll fry it!

 DCFC82D2-5BF5-43AA-A39D-77349A451DA1.jpeg   226.7K   8 downloads

[TOERUNNER]

I have spoken to molnar and that was the only option they offered me. My other option is to get a complete after market power unit, just not sure which way i should go

[yel327]

See how the motor is connected 415V STAR? Some motors you can change that to a DELTA connection which will be a 240V 3phase motor then. And buy a 240V VSD that has 240Vac single phase input and 240V 3phase output. But it'll end up costing as much as the motor.

 

Example:

 

https://www.ebay.com...&frcectupt=true

 

The nameplate on the motor will tell you if it can be STAR or DELTA. Mine is STAR only.

 

Unless you are an eleco I suggest you just change the motor. See if you can get its nameplate specs (the 240V single phase one)

[CI 0308]

I doubt that Molnar make electric motors. Option 1, Take the motor to an electric motor retailer and see if they have a single phase alternative WEG or similar (it is going to be bigger but you may get a frame that will mount up??) Option 2. A single phase to 3 phase variable frequency drive VFD.

Edited by CI 0308, 15 July 2020 - 06:53 PM.

[TOERUNNER]

Molnar use Australian made CMG motors which is good but my original question was will the hoist be painfully slow.

[yel327]

They don’t make motors, you can see the one on mine is a CMG. But they are the hoist manufacturer and they’d offer what they do for a reason. I’d find out why before going on a tangent.

A single phase 240V to 3 phase 415V VFD will only work on a 415V motor in two circumstances:

1. Motor can be connected in DELTA so it becomes a 240V 3phase motor.
2. You have access to 415V single phase (2 phases) which some older houses had as ranges used to be 415V single phase.

The other option is as per 2 above but also use a 240 to 415V single phase step up transformer, would have to be about 3kVA or more and you’d have trouble energising it off a domestic supply and domestic circuit breakers.

Just talk to Molnar about why they only offer a 4 pole 240V motor. It is a hydraulic pump, may be fine.

[lakeside]

Ask Molnar. They are an Aussie Company. Not sure whether mine is a 2 pole or 4 pole motor, just ran a 3 phase supply to it.

Set a mates hoist with contractors, timer and caps, prick of idea and noise. It’s not worth the trouble easier and cheaper to just buy a single phase. 

[yel327]

Set a mates hoist with contractors, timer and caps, prick of idea and noise. It’s not worth the trouble easier and cheaper to just buy a single phase.

Not sure what you mean? If you have a 3 phase supply the hoist works identically to single phase. No more noise or trouble.

[71xu1]

I have a Molnar single phase, funnily enough a mate just commented to me Yesterday how fast it is. Mine is an Australian made Molnar I have been told recently that they are no longer made in Australia, this came from a hoist servicer so not sure how accurate.

[TOERUNNER]

I have a Molnar single phase, funnily enough a mate just commented to me Yesterday how fast it is. Mine is an Australian made Molnar I have been told recently that they are no longer made in Australia, this came from a hoist servicer so not sure how accurate.

Hi 71xu1, you wouldn,t happen to know the make and model of your motor. my hoist is also australian made.

[CI 0308]

Have a look.

https://youtu.be/Z_juhqYt1Ks

Sent from my SM-A705YN using Tapatalk

[yel327]

Have a look.

https://youtu.be/Z_juhqYt1Ks

Sent from my SM-A705YN using Tapatalk

Exactly as I said. In that video he is using a VSD to run a 3phase 220/230/240Vac motor off a 220/230/240Vac single phase supply. The equivalent here is running a 380/415V 3phase motor off a 380/415V single phase supply. You cannot step up voltage in a small VSD. You can actually see in the video when he starts talking about connecting only L1 and L2 on the drive, he is connecting it 220V single phase (across two phases), not one phase and neutral. In the USA they run 220V 3 phase which gives them about 110/120V single phase to neutral. We run 415V 3phase which is about 230-240V single phase to neutral.

It will only work on a 415V 3ph motor if you connect the input of the drive across two phases, ie 415V single phase. Or you use a motor that can be connected STAR or DELTA. A 3ph motor connected in STAR at 415V will be 240V 3ph in DELTA. Then you can run it off a VSD with 240V single phase on the input.

[CI 0308]

 Or you use a motor that can be connected STAR or DELTA. A 3ph motor connected in STAR at 415V will be 240V 3ph in DELTA. Then you can run it off a VSD with 240V single phase on the input.

 

Correct, my point exactly and 3 phase 6 wire motors are common and cheap.

[yel327]

Which means buying another motor AND a VSD! If a 2 pole is needed finding a suitable flange mount 2 pole 3phase 2.2kW motor capable of being connected in Delta will mean buying new. OP might as well buy a single phase one! If a 4 pole is fine just buy it from Molnar.

[Rockoz]

Easiest thing to do is look at the plate on the motor.

It will have a frame type.

Ring an electrical motor rewinder and ask what the biggest motor you can get in single phase for the frame type and the highest RPM.

The rewinder will know where to source motors cheaply, as they often do so when some are fried to much to bother with rewinding, or it is cheaper to buy new than to rewind.

Getting a 3 phase motor to work with a VSD would be expensive in your situation.

 

 

As for plugging a 15A load into a 10A power point, it wont fry it.

The connections and contact patches etc are identical in a 10A and 15A.

The only difference is the earth pin, which is used purely for designation purposes, it has no actual electrical value.

These days, you can pretty much put as many power point on a circuit as you desire, as it is all limited by circuit breaker.

I will have to look up the exact rules one day. But the rules have relaxed a lot since I started in the game. Havent done domestic or similar work for a very long time.

[yel327]

Yes it will fry it, that is a false and dangerous statement. 10A sockets do not have pins, A or N sockets or switches rated for more than 10A. If you have 15A outlets with 10A switches and power pin sockets throw them away, they are a probably Chinese knockoffs.

I have been part of numerous electrical safety organisations and Standards etc since the 90’s and seen dozens of melted 10A sockets, leads etc that foolish people have been using with 15A devices. It is simply stupid to do so. You should only ever use a 15A or 20A docket with a 15A device, period. I have seen absolute morons buy $80,000 caravans and file down the earth pin on a lead as they won’t pay for an eleco to fit a 15A outlet.

[71xu1]

Fully lowered no load on hoist 25 seconds to full height  image.jpg   154.28K   3 downloads

[yel327]

That is a 2 pole 240V single phase motor. The OP said Molnar were only offering him a 4 pole. As it’s a hydraulic pump I still reckon it’ll make little difference.

[71xu1]

The picture I posted of the motor is also for a hydraulic pump, when I purchased the hoist from them I ticked the box for single phase. Ps my hoist is a two post.

Edited by 71xu1, 17 July 2020 - 09:02 PM.

[RallyRed]

Not a real answer to OP, sorry, but I looked at all this stuff, and ended up deciding it was easier to just buy a Mr. China single phase hoist, rather than a 2nd hand 3 ph.
Molnar.
p.s.we now have a 2 post and a 4 post, and even when lifting a 4WD, they dont seem to pull ANYWHERE near the rated full load current.
I suspect the vendors call up 15 amp supply, just in case.

Edited by RallyRed, 17 July 2020 - 10:26 PM.

[TOERUNNER]

Hi guys, i ended up getting a 240v motor from Cmg for under $500. I have just fitted it and it works fine . i was worried that it might be a bit slow as it spins at half the speed of the 3 phase motor,  it hits the top limit in 60 seconds, So i think it will be all good

[Rockoz]

Yes it will fry it, that is a false and dangerous statement. 10A sockets do not have pins, A or N sockets or switches rated for more than 10A. If you have 15A outlets with 10A switches and power pin sockets throw them away, they are a probably Chinese knockoffs.

I have been part of numerous electrical safety organisations and Standards etc since the 90’s and seen dozens of melted 10A sockets, leads etc that foolish people have been using with 15A devices. It is simply stupid to do so. You should only ever use a 15A or 20A docket with a 15A device, period. I have seen absolute morons buy $80,000 caravans and file down the earth pin on a lead as they won’t pay for an eleco to fit a 15A outlet.

Ive actually pulled them apart. Its my trade after all. And the topic of a lot of engineering studies as well

I used to have pics depicting it on an old computer. Might have to do so again.

I have done quite a lot of investigative work into the causes of electrical failures over the years.

Melted bits are primarily caused by a loose connection.

Have a look at the size of an old piece of fuse wire. Much much smaller diameter than the cable it is intended to protect.

Yet it will safely handle loads for a very long time.

The contact points on power point etc are large enough for currents way above their designated rating.

 

The idea of the larger earth pin is fantastic until it is taken to by the idiots.

In past versions of standards, you were limited to the number of points on a circuit.

Those days were predominantly where fuses were employed for protection. But they were also used incorrectly.

Now you can have virtually any number of outlets on a given circuit if it is protected by breakers.

With the added mandatory earth leakage protection these days, not a lot can go wrong or be dangerous.

Filed down earth pins and leads wired up by someone who reckons he knows how will always be a problem.

I have come across installations wired up by tradesmen that have managed to wire power points incorrectly.

 

A loose connection, especially when drawing higher currents becomes a runaway train of sorts.

The loose connection caused resistance and resultant heating, which causes more oxidising of the bits which causes more resistance.

Bits of the oxide drop away making it an even looser connection.

 

Cheers

 

Rob

[yel327]

You are correct in that you can limit the load on a circuit by use of breakers thus meaning limiting the number of outlets really becomes irrelevant, and this is why those limits were removed from AS/NZS3000 about 20 years ago. However you can easily overload a 10A GPO by pulling more than 10A through it. Most power circuits are protected by 16A or 20A breakers, some even 25A or 32A if the cable used is adequate in size and installation method. Each GPO is limited by what can be plugged into it, not the circuit protection. Clipsal for example make a 15A switch mech for a reason, that reason is the 10A one as used in standard 10A outlets is not rated for use above 10A. The GPO melting and subsequent damage I’ve seen was caused by currents higher than 10A, specifically by the “idiot” factor as you say of circumventing the earth pin limitation, and also by people overloading power boards without 10A thermal protection on them thus creating loads at the GPO greater than 10A.
Regardless, I think we agree the action of modifying a plug of a 15A device or lead so it can be plugged into a 10A socket is stupid.