# Motor runs without load but does not run with load



## smartatuls (Dec 12, 2017)

Hi,

On an overhead crane, CT motion runs on no load but does not run with load (10 tons).
Motor rated current is 2.9A. 
Drive current is 3 A (ATV320-1.1 kW). 
Tried with other drive (3 kW) and then it runs showing 2.4A as current consumption.
Again switched to original 1.1kW drive it runs once in a while but mostly does not run with load.

Does anyone know about how to use Torque Boost parameter in ATV320 drive? Will that help?
__________________
Thanks,
Smartatuls
Teaching Once is Learning Twice


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## 3DDesign (Oct 25, 2014)

Does THIS manual help?


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## 3DDesign (Oct 25, 2014)

Right after I posted that manual, I customer called about a Vibratory Tumbler (polishing machine) in a machine shop not working. It would start for about 3 sec. and shut down.
After calling the manufacturer, we determined the ATV312 driver was bad. I ordered a new one from Graybar Electric supply.


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## paulengr (Oct 8, 2017)

Torque boost is for V/Have mode only, not a mode you'd normally use on motion control. That's strictly can fans and pumps. Second what it does is that if you just did V/Hz then at low speeds it would stall. The motor needs a certain amount of current to generate flux and the rest is torque. Torque boost Jack's the voltage up at low speeds to keep the motor fluxed but it's just a guess. In vector mode the drive measures torque and adjusts voltage accordingly so as long as the drive is tuned properly (autotune is not just a good idea...it's required for vector), you get automatic compensation for this with one exception. Below around 1 Hz the drive is essentially seeing DC and can't measure torque. With an encoder this doesn't matter but without it, the drive is lost. This is why the hoist motion needs an encoder so you can hold loads (use motor as a brake). On all other motions you don't absolutely need it unless you are doing high precision positioning type control (servo). Vector drives used to be very expensive. Now it is free so even on pumps and fans it saves a little electricity too. One exception...vector mode cannot be used when you connect multiple motors in parallel to a single drive.

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## paulengr (Oct 8, 2017)

paulengr said:


> Torque boost is for V/Have mode only, not a mode you'd normally use on motion control. That's strictly can fans and pumps. Second what it does is that if you just did V/Hz then at low speeds it would stall. The motor needs a certain amount of current to generate flux and the rest is torque. Torque boost Jack's the voltage up at low speeds to keep the motor fluxed but it's just a guess. In vector mode the drive measures torque and adjusts voltage accordingly so as long as the drive is tuned properly (autotune is not just a good idea...it's required for vector), you get automatic compensation for this with one exception. Below around 1 Hz the drive is essentially seeing DC and can't measure torque. With an encoder this doesn't matter but without it, the drive is lost. This is why the hoist motion needs an encoder so you can hold loads (use motor as a brake). On all other motions you don't absolutely need it unless you are doing high precision positioning type control (servo). Vector drives used to be very expensive. Now it is free so even on pumps and fans it saves a little electricity too. One exception...vector mode cannot be used when you connect multiple motors in parallel to a single drive.
> 
> Sent from my SM-T350 using Tapatalk


I meant Volts/Hertz (V/Hz) stupid spell check.

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## paulengr (Oct 8, 2017)

It sounds like you partly solved your problem. If the settings are identical but drive 1 works and 2 doesn't, drive 1 is defective or you changed something else. Check the parameters carefully for differences. The drive software tool that Schneider gives away for free makes this easy. I'm not sure if you can do parameter compare on the 300 series like you can on the 900 series or not.

The 300 series by the way is meant as low performance cheap machine builder drives, kind of a "Walmart" drive. The kind of thing you mighf use on say a cooling fan. The 900 series is specifically designed as a crane drive. I only got certified on the 900 series because nobody is going to pay extra just for a certified technician for that kind of drive. That's what the original Altivar line started out as. Now it beats Allen Bradley.

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## Labhinder Singh (Jan 27, 2018)

Yes dear, just replace the motor because ur motor rotor got damaged (mivht be cut somewhere on rotor) due to which motor unable to build 100% torque


smartatuls said:


> Hi,
> 
> On an overhead crane, CT motion runs on no load but does not run with load (10 tons).
> Motor rated current is 2.9A.
> ...


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## smartatuls (Dec 12, 2017)

Drive connected was ATV320U11N4C(1.1kW, 3 A) but it was running motor without load only and did not move with load(10 Tons) condition.

A higher rating drive ATV320U15N4C (1.5kW, 4.1 A) connected but same problem is coming. Site engineer increased NCR(motor rated current) and ITH(Thermal current) as 4.5 and 6 and auto tuned then motion was working with load and showing current as (3 A to 4.5 A)

When tried with other motion drive(Long Travel, 3kW ) temporarily with actual motor details entered and auto tuned then it was working fine showing current consumption as 2.6 A.

Not sure why it is not working with 1.1kW or 1.5kW drive as per motor name plate details and auto tuned parameters.


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