Single phase Hoist brake motor, VFD for soft start soft stop ?

Thread Starter

Hermit by the sea

Joined Mar 12, 2021
5
Hi folks
Why is it that single phase VFD's have a bad rep ?
ATO sell a range of VFD's for single phase induction motors but they do not recommend using for a hoist ?
I am using, for many years, a 240V 2750W hoist motor on a hillside lift. I would like to have a slow start / slow stop.
Which product can I use and any explanation on how it works with the brake ?
Thank you.
 

MaxHeadRoom

Joined Jul 18, 2013
22,641
As per popularity, 3ph VFD and motors are popular with residential (non-industrial) users, reason: the single phase VFD's have a poor record when controlling 1ph induction motors due to their tendency to drop out of run under load, especially when rpm's drop.
With a VFD, you have configurable outputs, you could use one to indicate At-Zero-Speed and activate the brake with the output.
Max.
 

Thread Starter

Hermit by the sea

Joined Mar 12, 2021
5
As per popularity, 3ph VFD and motors are popular with residential (non-industrial) users, reason: the single phase VFD's have a poor record when controlling 1ph induction motors due to their tendency to drop out of run under load, especially when rpm's drop.
With a VFD, you have configurable outputs, you could use one to indicate At-Zero-Speed and activate the brake with the output.
Max.
Hi Maxheadroom
I read your old posts on similar questions, thank you for responding to this one. It’s difficult to find a replacement to the hoist I am using.
Everyone runs for the hills when they know it’s for transporting people. Can you suggest a VFD that would do what I need ? Thank you
 

Thread Starter

Hermit by the sea

Joined Mar 12, 2021
5
Hi Maxheadroom
I read your old posts on similar questions, thank you for responding to this one. It’s difficult to find a replacement to the hoist I am using.
Everyone runs for the hills when they know it’s for transporting people. Can you suggest a VFD that would do what I need ? Thank you
Sorry the motor is actually a 2hp single phase 220v
 

GetDeviceInfo

Joined Jun 7, 2009
1,806
I read your old posts on similar questions, thank you for responding to this one. It’s difficult to find a replacement to the hoist I am using.
Everyone runs for the hills when they know it’s for transporting people. Can you suggest a VFD that would do what I need ? Thank you
It’s not that they are running for the hills, it’s that they are not interested in gaining a stake in your situation. The party that provides your certifications should be the ones to ask, or the OEM.
 

Thread Starter

Hermit by the sea

Joined Mar 12, 2021
5
It’s not that they are running for the hills, it’s that they are not interested in gaining a stake in your situation. The party that provides your certifications should be the ones to ask, or the OEM.
Thank you. I understand, this is why it’s difficult to find help. There are no certifications or anyone to else so it’s on me to find out best I can..
 

Thread Starter

Hermit by the sea

Joined Mar 12, 2021
5
Might be worth looking at replacing the motor with a 3ph version and use a 1ph fed, VFD! ;)
Thank you , I think this would be best too. I don’t have a 3phase supply at the moment and what I have works so I’m trying to stay as close to it as possible. I guess I just have to buy a VFD and see how it goes. I’m also considering mechanical devices as the travel length is consistent.. thanks again for you input..
 

MisterBill2

Joined Jan 23, 2018
8,214
There are quite a few VSD systems that rectify the input power first, and so they can drive a 3-phase motor from a single phase mains connection. A friend uses one to drive his milling machine in a residential area with no 3-phase power available. It works quite well. So with the right VFD there is no need for 3-phase mains.
BUT for anything moving humans there are all sorts of additional rules and regulations. THAT can easily be the show-stopper. The lifts that I have seen use a hydraulic motor and a separate pump and then a simple valve to gently start moving. That is another possible solution. Not cheap at all, but quite good.
 

MaxHeadRoom

Joined Jul 18, 2013
22,641
There are also phase switching systems that directly switch the voltage from the three phases to produce different frequencies. The control logic is quite complex but the efficiency is quite high.
VFDs , both 1ph and 3ph supplied, generate a 3phase supply via BJT 3ph devices.
The first thing presented to the AC supply is a 3ph rectifier bank, to supply the BJT bridge.
The 1ph supplied versions usually go up to 5HP maximum.
Max.
 

shortbus

Joined Sep 30, 2009
8,429
The first thing presented to the AC supply is a 3ph rectifier bank, to supply the BJT bridge.
That quote was for something else. He was trying to explain the converters that take 3 phase at one frequency and change to another without the common bridge and transistors of a VFD. Think he was trying to mean "cycloconvertors", but doesn't have enough knowledge.
 
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