Motor Conection for VFD Application

Check the links inside the motor terminal cover for the correct connection arrangement in delta. It sounds as though one of the windings could be reversed.

I believe it's normal for an IEC 6 lead dual voltage motor to use the Delta winding pattern for the lower voltage, i.e. 240V, and the Star winding pattern for the higher voltage, i.e. 415V. Sounds to me as though you had it hooked up wrong the first time.

If the motor is drawing too much current (it is!!) then this is either misconnection or you are applying too much voltage.

Other posts recommend connections check etc, also set the VFD to a simple v/f control and set the starting voltage to its minimum setting with a 5 second acceleration time to see if this reduces this current. Working better in star seems to imply your voltage is too high causing the problem.

I take it that the motor is a 50Hz winding, if not, change the rated voltage and frequency in the VFD to the motor nameplate.

Dear all

yes the motor has 50Hz winding, and there is no question of misconnection as it is running ok in star.

Thing i want to know is should i lower the voltage entered in drive for star? ( currently it is 415V) What about torque ? well the running frequency for this application will be max 3 Hz.

The VFD has a motor rated voltage and frequency etc (415V and 50Hz, 7,5Aflc delta).

Your motor should be connected for delta, the 415V connection.

Also, you can programme the starting voltage, sometimes called 'boost' - this is the parameter you need to adjust to a lower value. What VFD is it?

3Hz is quite low for some inverters, this is normally better in 'automatic' control, letting the inverter change the voltage applied to keep the motor current correct for the actual load.

However, you should still be able to get a reasonable result at this Hz unless the load is high but I guess you're just trying to get it going in no load at the moment.