Check if motor power corresponds with the AC motor drive output power:

1) Voltage reading from the output legs (U/T1, V/T2, W/T3) should have voltage range of 208-240V AC. Use a multimeter to measure the voltage.

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 1.1

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 1.2

    (remove cover to expose power legs) Fig 1.3

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

 

                                                                            Fig 1.4

6) Reconnect power to the machine.

7) Switch on the disconnect switch by rotating the knob clockwise and then pushing up on the side tab to release the lock. You should be able to switch to the ‘on’ position.

                                       Fig 1.5

8) Press the ‘POWER ON’ button on the cabinet.

Fig 1.6

9) Power on the spindle.

Fig 1.7

10) You can now probe the output to motor legs for 220 V. Grab a multimeter and set it to read AC Voltage.

Fig 1.8

11) Probe any two of the output to motor power legs. In this case, U/T1 and W/T3 are being probed.

Fig 1.9

12) Ensure the voltage reading is 208 – 240 V. Any less than 208 or more than 240 indicates there is an issue.

13) If the voltage reading is not within the threshold for the motor output side (U/T1, V/T2 and W/T3), check the voltage readings from the input side (R/L1, S/L2 and T/L3).

14) Use the logic chart below to diagnose motor power issue:

Problem	Reason
Motor output voltage not within threshold (208 – 240) and motor input voltage not within threshold	Could indicate issue with power supply to the inverter, utilities issue consult w/ electrician
Motor output voltage not within threshold (208 – 240), but motor input voltage is within threshold	Could indicate issue with inverter