Check the wiring connections to U/T1, V/T2, W/T3 for possible short circuits:

1) A continuity test must be performed on the connection from the motor output power legs to the spindle power input pins to determine if a short is present.

2) WARNING: Begin by ensuring the machine is turned completely off and that the three phase power is disconnected. If the machine is still on, shut-down the machine using the appropriate shut-down procedure.

3) Open the front door of the electrical cabinet (this is the side with the power buttons). 

 Fig 2.1

4) Locate the inverter. Remove the front cover by pressing on the side tabs, pulling out and down. Remove the power wire cover by pressing on the perforation and pulling down.

 Remove Cover for Inverter – Fig 2.2  

 Remove Cover to Expose Power Legs Fig 2.3

5) The power wires should now be exposed. U/T1, V/T2 and W/T3 are used to send power to the spindle.

 Fig 2.4

6) Set a multimeter to measure ohms. When checking
for continuity, touch both probes together and take note of the reading. This
will be the same reading displayed if each conductor has continuity.

 Fig 2.5 – No Continuity

 Fig 2.6 – Continuity Exists, values may differ to your meter but cannot be ‘OL’)

7) Probe each power leg U/T1, V/T2 and W/T3 with each input pin on the spindle power cable. Check for a value on the multimeter. At least one of the pins numbered 1 through 3 should yield a value for each power leg.

8) For example, if checking U/T1 continuity: insert one lead of the multimeter onto the U/T1 power leg and the other end should be inserted into the spindle power cable pins 1 through 3 until one of them gives a value. Repeat the process for each power leg, a different corresponding pin should yield continuity for each power leg.

 Fig 2.7 – (probe power leg on motor output side of inverter)

 Fig 2.8 – (probe power input pin hole on spindle cable)

9) If there is no continuity, there could be an issue with the spindle power cable. If there is continuity, move on to check the ground connection between the spindle and the inverter.

10) Probe one side of the multimeter with the ground cable on the motor output side of the inverter. Place the other probe in the ground pin hole of the spindle power cable. Check for continuity.

Fig 2.9 – (probe ground on inverter motor output side)

 Fig 2.10 – (probe ground pin hole on spindle cable)

11) If there is no continuity, there could be an issue with the grounds.