What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?

• 05-05-12, 18:46
phatcreators
What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
What would happen bad if motor's rated FLA is 39 A (Amps) & parameter set on drive is 45 A (Amps) ?
• 05-05-12, 19:09
vignesh ssvv
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
the amount of current drawn by a motor will depend upon the voltage applied and the load given to motor. If low voltage than rated voltage is applied then the motor will draw more current.
Therefore your motor will not get affected due to high current setting.
• 05-05-12, 23:04
phatcreators
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
wouldn't it affect the winding of the motor ?
• 06-05-12, 03:33
vignesh ssvv
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
it won't affect the windings because the motor will draw more current than the rated current only during overload and when you apply low voltage.
• 06-05-12, 17:52
vignesh ssvv
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
i missed to say this in last post- when your motor is 100 percent trouble free then nothing will happen to your motor due to high current setting but problems like friction due friction in bearings or any over load will tend to draw more current. This will surely cause damage to the windings of the motor. Therefore it is not recommended to fix more current setting than than the rated current.
• 07-05-12, 22:08
phatcreators
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
ok, but if the motor has to run on half voltage lets say about 250 V or about 300 V than the full voltage i.e 380 to 400 Vac for about 15 minutes or so , what would happen bad ?
• 08-05-12, 20:05
phatcreators
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
• 10-05-12, 19:59
phatcreators
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
You should decrease the carrier frequency because it would reduce the amps at low speeds also ......... my opinion
• 03-06-12, 10:24
phatcreators
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
should I decrease the carrier frequency because it would reduce the amps at low speeds also ......... my opinion , what do you guys say ?

Also, i further pointed out that it takes higher amps than the rated FLA when its speed is between 60 m/min to 95 m/min , below and above this range it takes the amps under the rated FLA ...........
• 03-06-12, 11:50
FvM
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
To answer the latest post, it's necessary to refer to the original post again.
Quote:

What would happen bad if motor's rated FLA is 39 A (Amps) & parameter set on drive is 45 A (Amps) ?
It involves a risk of overheating the windings and possibly damaging the motor. The exact answer depends on a number of details.
- Does the motor provide thermal protection (PTC or temperature switches), is it connected?
- Is additional dynamical overcurrent allowed by the VFD?
- Do you operate the motor with currents beyond ratings (FLA) for extended times (several minutes or more) or only momentary
- If the overload is intermittent, is the motor able to cool down in between?

Quote:

ok, but if the motor has to run on half voltage lets say about 250 V or about 300 V than the full voltage i.e 380 to 400 Vac for about 15 minutes or so , what would happen bad ?
With VFD operated motors, motor voltage is varied according to speed and selected f/V characteristic. The interesting parameter for rated operation is motor current.

Quote:

You should decrease the carrier frequency because it would reduce the amps at low speeds also
It doesn't. The only relation of carrier frequency to current is that a lower carrier frequency allows slightly higher VFD output currents, at the expense of creating more audible noise.
• 03-06-12, 23:01
phatcreators
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
yes it has PTC ....

not for every time but sometimes do and when it does happen the drive displays the alarm of Drive Overloaded OL 2 and stops / trips the motor ..

Is additional dynamical overcurrent allowed by the VFD ? I couldn't understand your question properly but what i understand , i give you the answer , yes for a shorter period of time (for few seconds or for a half of a minute) it allows the motor to take more amps than the rated FLA but not for the longer periods .....

yeah it may cool down if it allowed to do so , but we start & run the motor & hence drive again ...... basically we don't give time it to cool down whenever it trips or stopped by the alarm that is given by vfd
• 03-06-12, 23:14
dineshdeshmuk
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
where is the PTC or PTCs are connected with the motor ? Are these connected with the motor's windings ?
• 04-06-12, 09:15
FvM
Re: What would happen bad if motor's FLA is 39 A & parameter set on drive is 45 A ?
I was asking for the dynamic overcurrent feature, because it is the preferred way to provide a certain amount of motor current above rated value. Setting the continous current limit in the VFD brings up a risk of actually overloading the motor. But I know that some heavy duty applications possibly don't work without increasing the current limit. In these cases, PTC protection is helpful to avoid motor damage.