Phase WU Short

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Excessive current has been detected between output terminals W and U, indicating a direct short circuit condition between motor phases W and U. This fault causes extremely high currents and will severely damage the drive's output transistors and the motor windings if not immediately resolved. Prompt investigation of wiring and motor integrity is crucial.

• Motor winding insulation breakdown between phases W and U, potentially from transient overvoltages, thermal cycling, or physical damage.
• Motor cable insulation failure between conductors W and U, often due to abrasion within cable glands, sharp edges, or environmental degradation.
• Accumulation of conductive dust or moisture shorting output terminals W and U at either the drive's output section or the motor's terminal box.
• Incorrect connection of motor leads during installation or maintenance, directly shorting phase W to U at the motor terminal block.
• Internal failure of the drive's output IGBTs for phases W or U, resulting in a direct short circuit within the drive's power stage.

Klicken Sie auf Schritte, um Ihren Fortschritt zu verfolgen.

1. 1

   1. Disconnect all motor power cables from drive output terminals U, V, W.

2. 2

   2. Measure the resistance between motor terminals W and U with a digital ohmmeter (expected typical value for motor phase resistance: 0.5-20 Ohms).

3. 3

   3. Perform an insulation resistance test (Megger) between motor conductors W and U at 500VDC for 60 seconds (expected reading: >1 MOhm).

4. 4

   4. Visually inspect the motor terminal box for burn marks, foreign objects, or insulation breakdown bridging phases W and U.

5. 5

   5. Measure the resistance between the disconnected motor cable conductors W and U at the drive end with an ohmmeter to confirm cable integrity.

6. 6

   6. If motor and cable test good, measure resistance between drive output terminals W and U with an ohmmeter (drive powered off, DC bus discharged) to check for an internal drive short.