Six-Terminal Motor with VFD Connection

<...output from the vfd the motor will be connected in star or delta mode....>

Delta if there are six terminals on the VFD. Otherwise, star.

"in delta mode it is 440 volt. motor in star it is 220 volt 50 hz motor" if i understand correct you are saying in delta connection the supply is 440v and in star connection it is 220v on the motor rating plate?

This is impossible and should be other way: delta = 220v and star = 440v.

What does the rating plate of the motor indicates?

Have you got this the right way round, or have I miss interpreted it? The motor is delta for 440V and start for 220V?? Doesn't sound right.

On the name plate, most times, there will be the motor voltage and a symbol ie. 440Δ for delta, or 415/240 (for here in Oz) which means the motor is wired in delta for 240V or star for 415V.

Anyway with your application you need to wire it as a 440v supply as that is the VFD's output voltage

And furthermore, with a single phase 240v? input VFD the output is 240v? three phase, so you would normally wire as delta.

4kW motor should be about 8 to 9 amps full load current, no load current should be about 4 to 5 amps.

VFD output is 400V at rated Hz (50?) so the motor should be connected for 400V, look on nameplate to see if this is delta or star connection (normally delta).

If no motor nameplate, connect in STAR and run to full speed at no load (on mains or 400V VFD) and check motor current by the VFD readout or current clamp. If its very low, like 1 amp or something, you then know the connection should be DELTA as the no load current is far too low showing reduced fluxing current as you are applying 400V to the 660V connection.

If you have a 220V VFD then you should connect motor for this connection IF its available. If your motor is 400V Delta / 660V STAR then you cannot do this.

In this case you can programme the VFD for 220V at 29Hz (on 50 Hz winding) and this will give constant torque to this speed on the 8-9amp winding. Thereafter, you will have constant power only at the reduced level limited by your voltage i.e. 1/√3 of 4kW = 2.3kW. If this is enough for your application - OK.

Hope this helps!

"which one is best vfd for my application .if ACC TIME is 1.5 sec and DEC time is 1.5 sec and min and max freq is 10.5 hz to 33hz ".

Not trying to be nasty, but I think you should get help from somebody with the necessary experience on vsd's and motors.

If you want to decelerate a load with a motor driven by a vsd in 1,5 seconds chances are that the drive will trip as a result of a over voltage on the DC buss of the vsd. For this you require a resistor connected to the DC circuit. Is your vsd equipped with this function (to connect a resistor)?

A six terminal motors wire as delta-star purposely for a reduced voltage automation starting comprising with two magnetic starters (y-delta) and a timer plus OL. If we conside the six-terminal leads out motor in conjunction with manufacturer's nameplate rating @240/415V, meaning initially it starts at wye @240V then at few seconds to delta so called reduced voltage y-delta starting. Thus theoretically, V(wye)phase voltage = 240Vx sq. root of 3= 415V(delta).

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BRUTUS, Northrop Grumman, SA