Hoffman gte 2500 duo lift vfd settings

[phil2401]

Hi. Im looking for some help with setting up the correct parameters on a vfd to operate a hoffman gte2500 duolift.
With no load on the lift it operates no issues,motor sounds strong. Vfd doesn't trip.
Once there is a car in the lift as soon as its taking any weight it starts to struggle.
Things to note. We installed the lift 3 weeks ago,using a vfd to power the 3phase motor.
the lift was operating and has lifted cars.
last week it was struggling to lift a heavier car,around 1600kgs so we'll within the limits of the lift.
At this point there was a pop at the motor and the electric tripped.
That pop fried invertor number one.
we founs the cables into the motor melted.(in hindsight the cables were old and potentially worn,damaged as its been dragged around and in storage for some years.we should of rewired to start with but unfortunately overlooked it so here we are) most probably the settings on the vfd were not correct which may of caused damage too.
New vfd is here,fitted and motor rewired from switch( motor tested with multimeter and all coils ok )
Ive searched the Internet for days and found some settings fornthe vfd,however im finding conflicting results depending on where I look on Google and with AI.
Ive set the suggested parameters that I found to match the motors plate information. The lift operates great until its underload then its useless.
Im looking for help to set the parameters to give the power/torque to safely lift the cars without causing damage to the motor or the vfd.
The motor is wired un delta as per the vfd manual instructions.

 

[Agroshield]

You do not describe the incoming supply to the VFD.

A 13A plug on the end of a skinny extension lead plugged into the house three doors away may not be suitable.

What does the motor actually do? Does it have a pulley on it or does it drive a hydraulic pump? If it is a mechanical connection, gearing it down will make it 'stronger' but 'slower'.

Are you ramping up the speed from switch on? Or just going from 0Hz to 50Hz in the blink of an eye? The motor is 1300 rpm. Parameter P22 is default for 2800rpm. What fault code appears on the VFD?

Have you the motor wired directly to the VFD? Are you controlling the motor only using the VFD? Any existing controls on the lift need to be wired to the VFD control circuitry.

It is a Chinese VFD and the plated kW on them is often rather optimistic. Empirical evidence suggests Chinese horses are 50% smaller than ISO ones, so it is wise to take that into consideration at purchase time.

 

[Guineafowl]

It looks like my lift, a screw type. I think you’ll need a lot more headroom in the VFD rating. Mine is 2700kg, has a 3.5 kW motor, and is run on a 7.5 kW rotary converter which is only just adequate. The lift/motor combination is very inefficient.

Take my 2-tonne-ish Defender, being lifted at 30mm/sec. The gravitational energy gained is only about 600 joules/sec, ie 600W of power in.

During lifting, at the motor, I get 380V and 11.9A per phase, ie 7.8 kVA.

Cos phi of the motor is only 0.65, giving around 5 kW of real power. Assume 80% efficiency to get 4 kW to the lift mechanism. Take away the 600W actually needed and you have a lot of heat being dissipated in the lift screws, etc. You also have to factor in the massive current surge when starting the motor with a car already partially lifted.

 

[frank horton]

I also run a Duo lift.....factory fresh it didn't really like range rovers etc.....
I asked the factory if they made a different screw shaft pulley, so I could change the gearing.....they refused point blank.....anyway, been told Hoffman has gone bump....cant be bothered to find out.....
Mine was running on mains supplied 3 phase....
Two problems ocured over time.....other than the lifting weight....
1. the belts used to get eaten, because of the design and the size of the motor pulley.....basically the belts only grabbed a 1/3rd of the pulley....
So to get it to work anything like proper they needed to be like bow strings.....
Not a fan of that....
2. I decided to make my own pulley from plywood just to test the idea, then if it works OK get some nylon and do the job properly....
Needless to say, it's as is.....
I also but some extra idlers in the system to create more motor pully belt contact....
The belts are now notched Kevlar.....
Now it can lift anything within it's range and I'm not forever changing burnt out belts....
I do have to make a new belt guard as the orignal doesn't fit any more.....

Just to add...I have a friend who had similar probs a Duo lift with VFD's and he modified the lift and wiring.....
made a pulley system like mine but then used a 3hp x 240v for up and on the other leg a 2hp motor to power it down....
As far as I know it's still working....I've moved away and lost touch....

Those are old belts from my stock as a try out but they have been replaced with decent ones now.....
it was a round-to-it kind of job but was to busy earning a living to care.....it worked just fine.....
Overall it looks like an abortion but it gets the job done....
PS those photo's were taken about 10-12 years ago in the old place.....
I will tidy everything up when it finally see's the light of day again.....
this summer.....yipeeeeeee.......

 

[phil2401]

You do not describe the incoming supply to the VFD.

A 13A plug on the end of a skinny extension lead plugged into the house three doors away may not be suitable.

What does the motor actually do? Does it have a pulley on it or does it drive a hydraulic pump? If it is a mechanical connection, gearing it down will make it 'stronger' but 'slower'.

Are you ramping up the speed from switch on? Or just going from 0Hz to 50Hz in the blink of an eye? The motor is 1300 rpm. Parameter P22 is default for 2800rpm. What fault code appears on the VFD?

Have you the motor wired directly to the VFD? Are you controlling the motor only using the VFD? Any existing controls on the lift need to be wired to the VFD control circuitry.

It is a Chinese VFD and the plated kW on them is often rather optimistic. Empirical evidence suggests Chinese horses are 50% smaller than ISO ones, so it is wise to take that into consideration at purchase time.

Power is direct from consumer unit,20amp, 6mm armoured. Into invertor,invertor to safey switch,to reversing switch to motor.
From that ive read the invertor( on paper) is enough to operate the unit.however if your saying its rated in chinesium donkeys rather than uk horse then this might be an issue.
It maybe possible to wire the controls to the vfd inputs rather than how its currently set up.its a screw lift so the motor drives pully

 

[Agroshield]

...invertor to safey switch, to reversing switch to motor.

In terms of expected lifespan of the VFD, that is a very dangerous way to wire it. In principle, there should not be any switching downstream of the VFD. Doing so has a much higher chance of releasing the magic smoke much earlier than it would otherwise do so naturally.

You did not touch on the frequency ramping issue in your answer. If you ramp up the Hz very slowly, perhaps over a 10 second period, it may work better.

Going from zero to full speed in an instant on a loaded ramp, including overcoming the static friction of the system (which is much greater than the moving friction) needs a huge amount of currents, and the bag of them that you have is not generously filled.

An alternative solution to new pulleys could be a reduction gearbox on the motor.

 

[phil2401]

The ramp up is set at 10 seconds.
Ill look at wiring the controls to the vfd rather than the current.
Do you have wiring diagram/guide

 

[Agroshield]

Do you have wiring diagram/guide

For the ramp? It is in Hungarian but electricity is multilingual.

 

[phil2401]

I also run a Duo lift.....factory fresh it didn't really like range rovers etc.....
I asked the factory if they made a different screw shaft pulley, so I could change the gearing.....they refused point blank.....anyway, been told Hoffman has gone bump....cant be bothered to find out.....
Mine was running on mains supplied 3 phase....
Two problems ocured over time.....other than the lifting weight....
1. the belts used to get eaten, because of the design and the size of the motor pulley.....basically the belts only grabbed a 1/3rd of the pulley....
So to get it to work anything like proper they needed to be like bow strings.....
Not a fan of that....
2. I decided to make my own pulley from plywood just to test the idea, then if it works OK get some nylon and do the job properly....
Needless to say, it's as is.....
I also but some extra idlers in the system to create more motor pully belt contact....
The belts are now notched Kevlar.....
Now it can lift anything within it's range and I'm not forever changing burnt out belts....
I do have to make a new belt guard as the orignal doesn't fit any more.....

Just to add...I have a friend who had similar probs a Duo lift with VFD's and he modified the lift and wiring.....
made a pulley system like mine but then used a 3hp x 240v for up and on the other leg a 2hp motor to power it down....
As far as I know it's still working....I've moved away and lost touch....
View attachment 522666

View attachment 522667
Those are old belts from my stock as a try out but they have been replaced with decent ones now.....
it was a round-to-it kind of job but was to busy earning a living to care.....it worked just fine.....
Overall it looks like an abortion but it gets the job done....
PS those photo's were taken about 10-12 years ago in the old place.....
I will tidy everything up when it finally see's the light of day again.....
this summer.....yipeeeeeee.......

Thats great information,ive seen these pictures online somewhere already.im back down at the shed tomorrow so I will be back at trying to figure a solution.

 

[phil2401]

Tested power at motor while running,getting variation between 80v-180v on each coil.