480V-3ph Motor connections to VFD Inverter

R

Rob2025

Member
Location
Toronto, Canada
Occupation
Electrician
Hi

I would like to learn more on 400V-3ph Motor connections to VFD driver.

In general, I found there are only 3 connections U, V, W available on VFD Inverter terminals for the motor. If there are only 3 wires connected from VFD to the motor and as there is no Neutral terminal available from VFD, then does it mean Motor is always connected in a Delta configuration?
Is there any way we connect the motor in Wye or Star configuration to VFD?
 
You connect the motor for the voltage output of the VFD. You show a 400 volt motor. That is an IEC voltage. They often have 6 leads are are connected in delta for a 230 volt supply, and in wye for a 400 volt supply.
 
The two answers above are correct.

The motor itself is a balanced 3 phase load, and may internally be connected wye or delta.

But that local neutral connection doesn't get connected to anything outside of the motor. The motor is a 3 phase load that doesn't require a supply neutral.
 
Reason a Nuetral is never required on three phase VFD'S is the three phase feeds a rectifier that on 480 volts produces approximately 665 DC Buss voltage that supplies power to IGBT'S.
 
garbo said:
Reason a Nuetral is never required on three phase VFD'S is the three phase feeds a rectifier that on 480 volts produces approximately 665 DC Buss voltage that supplies power to IGBT'S.
Click to expand...

That is correct, but I believe the OP is asking about the connection between the VFD and the motor, not the circuit supplying the VFD.

The OP was asking how they could connect a motor, internally wired in the wye configuration to a VFD.
 
To bring more clarity on my question, please see below the picture of the label on the motor that is currently connected to the VFD. The VFD output I measured is 400Vac-3Ph.

Motor label plate.JPG

Looking at this, what is motor configured as Delta or Wye?
If I say 400V, then it's not Y-connection and for 230/265V it's not a Delta connection!
 
The motor is wired in the wye connection, supplied by 3 phases from the inverter. The motor star point isn't connected to anything outside of the motor.
 
Rob2025 said:
Looking at this, what is motor configured as Delta or Wye?
Click to expand...
Motors are always supplied as delta loads, using three lines only, and no neutral.

You're looking at the internal wiring configuration, wye vs delta, not the supply.

In Tom's diagram above, the dotted line is not brought out of the motor wiring.
 
LarryFine said:
Motors are always supplied as delta loads, using three lines only, and no neutral.
Click to expand...
Well, I think you mean that for 3 phase motors you only supply 3 wires (leaving out Y-D starting and 2 speed motors for this discussion). The INTERNAL connections in the motor windings can be configured as wye or delta as the case may be.

With dual voltage IEC motors like what is shown, the internal motor connections are ALWAYS configured as delta for the low voltage, wye for the higher voltage. A memory trick is the D for delta is “lower” in the alphabet and Y for wye (or S for star) is “higher” in the alphabet.
 
You must log in or register to reply here.
Top