VFD Amp. issue

i have a motor (3.7kw ) which draws current around 5amps when running on DOL, same motor when running with vfd on max speed draws 12.5 amp. current

How are you measuring the motor amps. My guess would be like most people you are using a standard clamp on AMP meter. That’s fine for the DOL reading and should give you an accurate reading. But that’s reading a pure sinusoidal wave form.
The problem is the output of a VFD is not sinusoidal. Depending on the VFD the output may be a pulsed square wave others may produce a quasi sinusoidal wave form. Your clamp on meter cannot read this correctly. You should never use a clamp on amp meter on the output of a VFD. The best is to read the VFD displayed motor amps. When you do read it remember that with DOL you are reading full line voltage with the motor running at full rated speed (of course minus the motor slip due to load) With a VFD you are reading the output of the VFD it could be from 6 Hz to 120Hz or more with the speed change you also get an amp change motor speed and load will change with a change in Hz. Lower speed can cause high current and the reverse is also possible depending on the load conditions.
Some people have had good success reading the line current on the input to the VFD it will be a true reading of the total load but it will be higher than the motor load. ( Motor load + VFD power + heat loss) all these lead to the total power used.
I hope this helps

Adding to Gary's reply you just say at max speed with the VFD . But is this the same speed as the DOL reading ie if your supply is 50 Hz was the VFD set at 50 Hz .
Also check the output voltage as well as the amps on the VFD display .
Paul

Thanks for the reply. Iam referring to vfd display as well as clamp meter reading for amp. Display there is some difference between the two but reading is around 12 in case of vfd and in case of dol referring to clamp meter reading is around 5.

Something doesn’t seam quite right
I see that you are in India if my information is correct the normal line voltage is 220 Volts 3 Phase 50Hz
A 3.7 kw motor should pull about 12 amps full load with a 220 volt 3Ph supply.
When connected DOL I assume that you are measuring 1 phase at a time.
If you are actually drawing 5 amps you using about 1.8kw at 220 VAC
These numbers are not completely accurate I think the correction factor is * .717 but you get the idea.
The actual value is not important the amps need to be about the same in all 3 leads
Are you measuring all 3 phases?
What are the amps of each phase?
Is each phase in your case should be within 4 to 6 amp range?
Put the clamp on amp meter around all 3 motor leads at the same time. What is the amps of the combined phases?
It should be Zero (0) all three phases cancel each other out, the sum of all 3 should be zero.

The VFD calculates the load amps a bit differently. They measure the amps on each motor lead then averages the 3 measurements and display the average as the motor amps.
I would expect the 2 readings to be close to the same but over a 2 to 1 difference seams way out of line.
Without being there myself it’s hard to be sure.
Unlike the US some countries us an ungrounded electrical system or a poorly grounded system. Please don’t get me wrong I am not pointing fingers or trying to put India down by any means. The US had and still has in some areas ungrounded power systems more here in the Northeast then other areas. Some are just not repaired as needed and other are deliberately ungrounded. That’s another discussion.
By measuring the amps on each motor lead and the amps of the combined 3 motor leads at the same time we may be able to find out what’s happening. If you measure amps when connected around all three motor leads then I would look at a ground fault in the motor. A high current going through 1 phase through the faulted motor frame back to the supply source through the building structure. If you are connected to an ungrounded source you will not see this while connected DOL unless the motor protection is set really tight (Most are not). But when connected through a VFD the VFD measures all the current in all the motor leads and averages then together and displays the result. The amp doing work in the motor + the amps going back to the power supply through the structure. This could account for the difference in the 2 measurements.
I hope this helps
Happy Holidays to All

Another possibility. I don't know if you're using an encoder with the VFD or not, but if you are, you can have a high current problem if the tuning is too tight. The easy way to check this is to change the VFD parameters so that it's using volts / hertz control instead of one of the more advanced control methods. If the output current from the VFD goes down to a normal level, then you know to take a harder look at you parameter settings.

It sounds like the DOL voltage is 220VAC and the frequency is 50hz. When checking the motor on VFD power, use the VFD display to find motor voltage and frequency. They should be the same as DOL or your current comparison is not valid.

You may have to adjust the programming of the VFD to get these two items to match the DOL values.

Then check the current using the VFD display. Even the best clamp-on ammeters cannot read the PWM current accurately.