Wye-Delta Contactor - How it Works and Troubleshooting Guide

How it Works

Some Haas machines use a Wye-Delta contactor assembly to manage the configuration of the motor windings. The spindle motor starts in the low-speed Wye winding. The contactor switches to the Delta winding at high speeds. The Delta winding is more efficient at higher speeds. With a Wye-Delta configuration, the machine maintains a consistent or high torque at both low and high spindle speeds.

  1. Delta contactor (K5)
  2. Wye contactor (K4)
  3. A1 connectors
  4. A2 connectors
  5. Spindle motor cables
  6. Jumper

The output from the vector drive terminals 9, 10, and 11 are connected to the spindle motor leads 1, 2, and 3 and the Delta contactor, K5. The K5 contactor is connected to the Wye contactor, K4, through a set of jumpers. The K5 contactor is also connected to the spindle motor leads 4, 5, and 6. The contactors have auxiliary switches wired as an interlock mechanism so both contactors are not energized simultaneously.

  1. When the machine powers up, the Wye contactor, K4, closes, and completes the Wye winding configuration.
  2. At a certain RPM, determined by the frequency of the vector drive, the processor will command the vector drive to stop momentarily.
  3. When the Wye contactor de-energizes, the Delta contactor is energized a few miliseconds later, and connects the vector drive outputs to the motor terminals 4, 5, and 6.
  4. Again, the signals to de-energize the Wye coil and energize the Delta coil are sent by the I/O board.
  5. During deceleration, the Wye-Delta contactor switches back from Delta to Wye when the spindle RPM reaches the switch point.
Symptom Possible Cause Corrective Action Section
Alarm 236 SPINDLE MOTOR OVERLOAD, Alarm 2041 VECTOR DRIVE OR SPINDLE AMPLIFIER-OVERLOAD, and the spindle load pegs to 200% when any spindle speed is commanded. There is an open coil on one of the Wye-Delta contactors. Check the Wye-Delta connections for arching or burn marks. Make sure the connections are tight. 1
There is no voltage from the I/O PCB to the Wye contactor coil. Measure the resistance and the voltage. 2
The encoder belt is damaged. Check the encoder belt and encoder connections. 3
Alarm 236 SPINDLE MOTOR OVERLOAD, Alarm 2041 VECTOR DRIVE OR SPINDLE AMPLIFIER-OVERLOAD, and the spindle load pegs to 200% when speeds above 2500 rpm are commanded. The machine operates properly at low speeds. There no voltage from the I/O PCB to the Delta contactor coil. Measure the resistance and the voltage.

Check the diagnostic page to coordinate when to measure the voltage across the delta contactor coil.

4
Alarm 123 SPINDLE DRIVE FAULT at any spindle speed, and Alarm 2040 VECTOR DRIVE OR SPINDLE AMPLIFIER-SHORT CIRCUIT. Faulty Wye-Delta contactor assembly. Check the Wye-Delta connections for arching or burn marks. Make sure the connections are tight. 5
Faulty vector drive. Inspect the vector drive and look for a shorted output. 6

Section 1

Symptom: Alarm 236 SPINDLE MOTOR OVERLOAD, Alarm 2041 VECTOR DRIVE OR SPINDLE AMPLIFIER-OVERLOAD, and the spindle load pegs to 200% when any spindle speed is commanded.

or

When speeds above 2500 rpm are commanded.

Possible Cause: There is an open coil on one of the Wye-Delta contactors coil.

Corrective Action:

Check the Wye-Delta connections for arching or burn marks. Make sure the connections are tight.

With the machine OFF, measure the resistance across the coil between connectors A1 and A2. The resistance should read 50-100 Ohms. If the reading is open, then the coil is defective.

Section 2

Symptom: Alarm 236 SPINDLE MOTOR OVERLOAD, Alarm 2041 VECTOR DRIVE OR SPINDLE AMPLIFIER-OVERLOAD, and the spindle load pegs to 200% when speeds below 2500 rpm are commanded. The machine operates properly at low speeds.

Possible Cause: There is no voltage from the I/O PCB to the Wye contactor coil.

Corrective Action:

Power up the machine and press RESET. Measure the voltage across the coil between the A1 and A2 connectors of the Wye contactor. It should read 120 VAC.

  1. If the voltage is correct, but the contactor does not engage, the contactor may have a mechanical issue.
  2. If there is no voltage present, the problem may be caused by the I/O PCB. Go to diy.haascnc.com to troubleshoot the I/O PCB.

Section 3

Symptom: Alarm 123 SPINDLE DRIVE FAULT at any spindle speed, and Alarm 2040 VECTOR DRIVE OR SPINDLE AMPLIFIER-SHORT CIRCUIT.

Possible Cause: The spindle encoder belt is damaged.

Corrective Action:

Find the cause of the spindle orientation error.

Make sure spindle drive and encoder belts have the correct tension. Make sure the spindle motor pulley and encoder pulley are not worn.

Go to diy.haascnc.com to troubleshoot the encoder belt.

Section 4

Symptom: Alarm 236 SPINDLE MOTOR OVERLOAD, Alarm 2041 VECTOR DRIVE OR SPINDLE AMPLIFIER-OVERLOAD, and the spindle load pegs to 200% when speeds above 2500 rpm are commanded. The machine operates properly at low speeds.

Possible Cause: There is no voltage from the I/O PCB to the Delta contactor coil.

Corrective Action:

Power-up the machine and enter a program in MDI that commands the spindle to spin at 1800 rpm. Slowly increase the spindle speed while observing the diagnostics output page. Look at bit 15 , Spindle D:Y. At the moment this bit changes from 0 to 1, the Delta contactor is energized. Measure the voltage across the Delta contactor’s coil between the A1 and A2 connectors.

  1. If the voltage is correct, but the contactor does not engage, the contactor may have a mechanical issue.
  2. If there is no voltage present, the problem may be caused by the I/O PCB. Go to diy.haascnc.com to troubleshoot the I/O PCB.

Section 5

Symptom: Alarm 123 SPINDLE DRIVE FAULT at any spindle speed, and Alarm 2040 VECTOR DRIVE OR SPINDLE AMPLIFIER-SHORT CIRCUIT.

Possible Cause: Faulty Wye-Delta contactor assembly.

Corrective Action:

Inspect the Wye-Delta assembly. Make sure that all connections are tight, and that there are no signs of arching or burn marks on the contactors, burnt marks on the jumper bus-bar or contacts. Power-up the machine and make sure that only the Wye contactor is energized when no spindle speed is commanded. If both contactors are closed at the same time, one of the contactors may be stuck (welded shut). The vector drive sees this condition as a short.

Section 6

Symptom: Alarm 123 SPINDLE DRIVE FAULT at any spindle speed, and Alarm 2040 VECTOR DRIVE OR SPINDLE AMPLIFIER-SHORT CIRCUIT.

Possible Cause: Shorted vector drive output.

Corrective Action:

Go to diy.haascnc.com to troubleshoot the vector drive.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.

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