Changing Motor Nameplate

You can alter the plate to what ever you like.

Unfortunately the manufactures may disagree with you! if you give a guarantee to this machine, it's you that will be held liable

I believe you would be better off with 64.5kw (~57.5kw*56/50), 102 A(that is the current rating for the conductors in the motor), 426 v, 56 Hz, 1650 RPM(Synchronous less the 30 rpm).

You may want to cheque the drive parameters to make sure there is not one that directly limits the output volts.

What flavour of PF? PF 700?

What is the application - Fan?

[Motor NP Volts] The motor nameplate base voltage defines the output voltage, when operating at rated current, rated speed, and rated temperature. (PF 700 - Reference Manual Aug 2004 - pg 2-117) - I would have to delve further if other parameters will cut you off on the output volts - but if you need 430 vac output and supply the drive with 430vac, you should be able to get 430vac out.

I ask about the load, because if it is a fan I believe the load goes up with the cube of the speed. for 56/50 **3 the power goes up to 140% for a fan - If the voltage does not rise, but the speed does, then you will have about 140% of the current drawn.

If the motor was not loaded then that current is too high.

As a point of reference, for slitter motors on Paper Machine Winders we commonly use 50 Hz rated 230vac motors and run them at 90HZ to 100Hz at 460vac - it doubles their HP !

This is for a fan, This is a PF700 replacing a 1336.

You will need to supply the VFD with 460 to 480V. That is within its rating.

Confirm the fan load at the higher speed does not overload your motor.

Set P54 to440V

Set P55 to 56 Hz (or even 60Hz)

Set P82 to 56Hz

Set P83 to 60Hz

Set P91 to 56Hz

Set P202 to High (voltage class) - May need to be set first.

Let me know if the settings "take"

You should be able to enter the correct nameplate data then change the maximum speed parameter in the VFD to allow for overspeed. The VFD will (usually) continue the V/Hz ratio above rated speed as much as possible. You can check if it does this (the VFD) by bringing up motor voltage on the display and running the motor up to 1646 RPM and monitoring the voltage that the VFD applies (via it's display).

Generally your name plate numbers would be entered into the VSD. Having said that I have not worked with Powerflex units and don't know how much data they take from the real world.

You should put the original NP values in. What you get out will depend on the motors ability to produce that torque. The more you overspeed less actual ower you have available. Trying to trick the VSD only causes fault alarms as it can not get the expected numbers from the motor.

Yep. The selected motor is too small. There is every chance of its becoming a short-lived convector heater instead.

Yes, I am trying this option to mantain my V/hz ratio.I believe the values GW suggested are more realistic.If the torque is maintained and the rpm's is more than 50Hz then I am going to get more power off the motor....The reason why I want to change name plate details is because I set the drive max Volts too 440v and max frequency to 56Hz, but when the motor was running on 56Hz, the Volts on the Drive was 400V, and the amps was 140A.(close to tripping)

I understand. When I look back at what I did with a Lenze to overspeed a motor I did pretty much what you indicated in your original post. I had a 200V, 4 pole motor at 1450 RPM and I entered data as a 400V motor at 2950 to get the VFD to output 400V. I used the same current as for 200V running at 1450RPM though as the drive outputs twice power at twice speed provided the V/Hz can be met - current remains constant as torque is constant in this region.

The only change I would make to your original data is to keep the current at 102 Amps and power to 57.5 * 1646/1470 => 64kW.

So 64kW, 102A, 430V, 1646RPM, 56Hz.

That way the drive should be giving you 380V at 1470RPM. The KW and current will only be used for autotune and protection.

I am not an expert in this subject but have delved into ACIM overspeed operation a fair bit - even so - take advice with a grain of salt.

Later edit: I see GW posted this already - I agree with his post.

The torque will not be same when the frequency is increased.

If you increase the output frequency, the output voltage will also be increased.

Some of the motors have a name plate with 3 different frequency. Remember that If you increase the frequency ( The voltage will also be increased), the heating problem will occur. Therefore, an external fan is used in that kind of application.

Please check Lenze AC motor catalouge,. These are shown as a graph and as a motor name plate.

The main consideration on VFD application should be Motor Torque, speed and Motor Current.

You can use the motor 120% loaded but external fan should be keep in mind.

In conclusion, You need identify what are the requirements of your system.

This is will be your motor`s output.

And then, your motor selection will come. Here, If you have a current motor, you will need the check the motor graphs from the manual. The graph will show you the limit of the motor.

NO. The details on the manufacturers plate are what the motor is, what the motor has been designed for. Do not change them.

If you choose to over run the motor from a VSD that is a decision you make based on your experience as an engineer. In the event the motor failed and an injury occurred you may have to provide calculations or something to support your judgement to over run the motor.

Remember on a motor not specifically designed to run from a VSD once you are below about 20 Hz the fan cooling is almost non existant.

<...overspeed this motor for constant torque operation...>

So, were the drive coupling to break, what is there to stop this motor accelerating to the point of catastrophic self-disassembly?

It's not a series wound DC motor, it's being controlled by an electronic variable frequency controller - it can't "accelerat[e] to the point of catastrophic self-disassembly".

He's running it 12% overspeed - it's just not that big a deal. On 60Hz it would run faster than the 56Hz he is planning. Read up on AC Induction Motors and the Volt/Hertz relationship.

Just establishing that <...constant torque...> is balderdash.

"Just establishing that <...constant torque...> is balderdash"

Is that statement in general or for my application.I do not doubt you , but may you please elaborate.

Try #25⇓.

Consider the mechanical coupling breaking. The <...constant torque...> concept means that the motor must now accelerate to produce an output torque that it cannot now achieve.

So it's still balderdash/baloney/nonsense, etc.

If you want higher output voltage from the VFD, you must increase the input voltage.

A VFD can never give a higher output voltage then the input voltage.

There are two solutions

• solution a)
• a motor 230/400V connected in delta with a VFD supplied with 400V.
• programming the Hz/V constant line changing point to 87Hz @ 400V
• be sure to select the size of the VFD according the motor current @230V
• solution b)
• a transformer that increases the voltage to a level above 400 V
• using this higher voltage as input voltage to the VFD
• programming the motor nameplate parameters as they are.

Thanks everyone for the info, I believe the problem is the 400v Powerflex.The max. output on this drive is the rated voltage which is 400v whereas on the 1336 the max. output was 120% of the rated voltage.I may have to try the Power flex 480V.

Did setting P202 to High "take"? It should have set the drive to run at 480Volt output max.

This application is called " torque control" By doing that you will get more torque from the motor.

You can do implement 480V but, you need to watch the current and temperature. As I mentioned earlier, you may need an external fan. If there an thermal sensor attached the motor, this will definitely make your application easier. As a result of this, you will not be worried about the motor.

I am not familiar p202. I guess this is a parameter code on your driver.

No, you are keeping the V/Hz constant. The application is in the constant torque region (Not constant HP). The motor will not be over excited. We are keeping the motor NP current rating the same. If set for flux vector mode the magnetization current will be held constant through the operating range. Overheating will only occur at low speeds when the motor fan runs too slowly - but this will not be the case when you want to run it fast. This drive is a fan application, and the work load drops off sharply with decreased speed.

The risk of running a fan fast is that the load goes up with the cube - NOT an application for constant HP operation. As long as the motor has sufficient power for the increased speed, then running 12% fast in the constant torque region will not cause any issues.

P202 sets the "out off box" rating of the drive to 400 (low) or to 480 (high). If you do a parameter reset it will set it back to low - that matches the drive NP, but according to the software reference manual you can set it to high.

see Rockwell publication PFLEX-RM004A-ENE - OCT 2006 page 115 - "Voltage Class"

The Name Plate Rating is what the manufacture rates the motor for and should not be changed.

If you are exceeding these, you have the wrong motor for the job, regardless of the VSD you are using.

Get the correct motor for the job and make everyones life and wallet safer.

Regards,
Sapper

Many factor will after by doing so..

May be you will endup burning your motor..

distance?application?why you want to increase power rating in vsd?..

yes you can set your max voltage to 460V but my suggession is specify motor nameplate and rating for safety and efficiency of motor and drive...

It is rather difficult to conceive a mechanical load that produces <...constant torque...> at all speeds that this <...3 phase induction motor...VSD...> combination is expected to drive.

At zero speed, for example, a <...constant torque...> load turns the <...motor...> into a short-lived convector heater.