VFD 400VAC adjustment 1

[powerjunx]

Hello, I got a burn out motor winding due to mis-configuration of VFD setting. Yet, i could never find motor data setting on VFD for Voltage rating, however only percent voltage output (VFD) is available.

So i tried to play along this voltage output as well as frequency adjustment to coincide with the motor specs. I am not sure if this setting is correct with VFD at V/F mode controlled by pot, Please i need your comments.

VFD specs: 440V/60HZ, 3 Phase, Model: LG-iG5A
Motor specs: 400V/50HZ, 3 Phase.

"..the more, the merrier" Genghis Khan

 

[John2025]

Take this with grain of salt, but the "Output Voltage Adjustment" on page section 7 page 17 seems like the way to correct for your 400 volt motor. 400/440 = 91%.
I wonder if that's really the cause of the motor failure. Is the motor inverter duty? Have you set the Motor Rated Current (page 5-12)? Overload settings (Chapter 10)?

 

[powerjunx]

John2025, i think i am in the right adjustment for my voltage output reducing 100%(440v) down to 91% (400v)setting. Thank you for confirming me this.

But i am not sure this make sense for vfd in v/f mode controlled by pot. Anyway, i had measured the vfd output, 400v/50hz for pot full range unlike before as 440v/60hz.

After the motor winding was damage. I investigated the cause first checking vfd settings, as i found had loaded with default value settings. Only later i verified that the v & f were set to 440v, 60 hz, respectively. So i assume, this causes the problem where the motor recieves over voltage 440v and over frequency to 60hz (about more than 20% rated freq). Rated current is fine but overload current time was set to 60 sec.

I am not sure this motor is inverter duty..but i saw most applications of such motor replacement ( different maker) comes in pair with vfd.

By the way, motor application is for exhaust duct fan.


"..the more, the merrier" Genghis Khan

 

[itsmoked]

Ah. It sounds like your motor was greatly overloaded and hence "failed". It had nothing to do with voltage because if the motor was running at 60Hz the 440V or actually 460V would've been the expected voltage.

When you spun the fan 6/5ths faster than desired you asked for about 50% more power from the motor.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

What is your line voltage? The VFD cannot put out any voltage that it was not given. So if you have 400V available, it could not put out 440V.

But the default setting should have been ok. 440V 60 Hz sets up a V/Hz ratio of 7.33:1. The motor's design V/Hz ratio, 400/50, is 8:1. As long as you are within 10% the motor should be fine. But if you began manually trying to mess with it, you may have inadvertently created a detrimental situation.

Hard to tell though, you didn't provide enough information.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

 

[John2025]

I missed the 50Hz on the motor. You probably need to set the Base Frequency (7-17) and the Max Frequency to 50Hz (7-21). For a fan, you may want to set the V/Hz Pattern to 1, per the manual(7-17). I'd look hard at the overload settings and set them conservatively.

 

[powerjunx]

Itsmoked, thanks! overloading causes the motor to fail as its spin faster than the rated rpm.

Jraef, line voltage is 440V.

"..the more, the merrier" Genghis Khan