Single to 3 phase converter

[HomeCert ltd]

Hi All,

I'm after a little help/advise from anyone who has any knownledge or experience in a single to 3-phase inverters.

My scenario:
We're in the final process of finishing a care home rewire, they have a 3-phase lift being installed. Everything's in place and been ran etc...

UK power networks has just given the owner a quote of over 100k to upgrade the current supply to a 3-phase supply to accommodate the 3-phase lift.

Has anyone ever fitted a 3-phase inverter? The installation currently has a 100amp supply but the loading is minimal. The lift is 31.7amps (37.8amps start up). Can I supply a 3-phase inverter with a 6mm 40amp MCB from my single phase and then supply the lift that way.

Has anyone ever installed one before? Recommendations or advise is much appreciated.

 

[ElectroChem]

The biggest 1-3 phase inverters I use top out at 2.2kW, you're talking ten times that size. Plus, supplying 40A of 3-ph startup off a single line is going to fully use that 100A supply, then some more.

Bottom line, if your client wants a 20kW lift motor, they need to stump up for 3 phase incomers.

 

[dmxtothemax]

Didn't he say 40A was the start-up current ?
Which is more like 10KW
Where did 22kw come from ?

 

[Andy-1960]

A standard motor inverter would not work anyway due to the fact you are not just feeding a motor, you would be feeding controls, lighting, etc.
Only option would be a rotary converter for this type of application, but even then I do not think the supply you have available is big enough. May be worth investigating though, as UKPN may be able to increase the size of the existing single phase supply for a lot less than £100k
https://www.simplypowersupply.com/pdf/mtrt.pdf

 

[marconi]

Is it a requirement for the lift to be always available? If so then the converter must be running all the time. I suggest you find out the no load power consumption of the converter and calculate its background electricity cost.

Can the motor in the lift be swapped for a single phase one with soft-start controller? See:

http://cmsapps.sea.siemens.com/controls/speedfax07/07speedfax_pdfs/07speedfax_16/16_165-170.pdf

 

[ElectroChem]

Didn't he say 40A was the start-up current ?
Which is more like 10KW
Where did 22kw come from ?

22kW was off my head with no working. Looked it up and an 18kW 415V motor at 0.8pf pulls ~32A FLC, as stated in the OP. To power that same 18kW off a single phase supply is 97A before conversion losses! I don't know where he got 37.8A startup from, a heavy traction lift motor is more likely to pull 100+ at startup.

 

[Strima]

Good planning on the designers/builders/lift owners parts of going ahead without checking the feasibility of 3 phase first...

What is the expected usage of the lift? i.e. frequency of use, weight in it etc?

 

[snowhead]

Somebody better speak to the Lift installation company before any more plans are made I doubt they will accept an inverter supply.

The lift will form part of the Fire Escape route, it will have to be bullet proof.

 

[Spoon]

Who thought it would be a good idea to design a 3 phase lift into a single phase house? Do they not do single phase lifts?

 

[HomeCert ltd]

The lift is only small, and is literally going from ground to first. I've worked in one of their care homes before and the lift which was installed there was literally supplied via a 13amp plug top.

Apparently this specific lift will only come as 3-phase.
All the carriage lights and shaft lighting is supplied separately by a seperate DB situated in the corridor cupboard. Looking at the Lift document it says total running current 26.5 amps and total starting current 37.1 amps.

I was under the impression this was across phases so running current roughly 9 amps per phase, and starting current 13amps per phase.

 

[HomeCert ltd]

I've just attached a screen shot of some specs on the drawings

 

[Andy-1960]

No, that is the current per phase.

 

[Leesparkykent]

Somebody better speak to the Lift installation company before any more plans are made I doubt they will accept an inverter supply.

The lift will form part of the Fire Escape route, it will have to be bullet proof.

Will it? Every block of flats I've ever done the lift is grounded in the event of a fire.

 

[davesparks]

Somebody better speak to the Lift installation company before any more plans are made I doubt they will accept an inverter supply.

The lift will form part of the Fire Escape route, it will have to be bullet proof.

Only if it is designed to be an evacuation lift, if it’s just a normal lift then it won’t

 

[snowhead]

Will it? Every block of flats I've ever done the lift is grounded in the event of a fire.

It's not a block of flats with able bodied people in it.

A true Fire escape lift is isolated from the main building and the power supply is run in a route so as not to be affected by Fire.

Even if the O.P lift is not a true Fire escape lift, it may well form part of the Fire escape strategy if Care home residents are above ground floor level.

 

[Deleted member 105166]

How often will it be used? Is a silenced diesel generator with remote start an option? Probably £85k cheaper than what the DNO have quoted and possibly cheaper ongoing.

 

[westward10]

It is correct that a lift for general use could be incorporated into an escape plan in an emergency situation after a risk assessment and a controlled strategic plan but generally this would be considered a high risk policy. Lifts which have been put in place as part of an escape route are subject to strict legal requirements and are generally only considered where vertical footfall is not free flowing such as a hospital where mobility may be restricted.

 

[Strima]

DC motor with battery back up?

 

[Chris1234]

The motor is rated at under 12kW.
You can use a 1ph - 3ph VFD to control just a 3ph motor. The existing controls would be wired to the VFD controls, fairly simple if you understand the way the lift works and safety requirements etc.
But will the lift company want/know how to redesign their lift for a one off project?
No.

 

[Andy-1960]

You have to be very careful with hoist motors and vsd’s.