Input Voltage Imbalance (Adv. Code 0)

What does 12 mean?

This fault is triggered when the drive detects a significant voltage imbalance between its input phases or a complete loss of one phase (single-phase condition) while operating under load. Such conditions can lead to excessive current draw, overheating of input components, and potential damage to the drive's input rectifier and DC bus.

• Loss of one incoming AC phase (single-phasing) due to a blown fuse, tripped breaker, or open conductor in the supply line.
• Significant voltage imbalance (e.g., >3%) between input phases (L1, L2, L3) caused by utility issues or unbalanced loads on the same transformer.
• Loose or corroded connections at the drive's input terminals (L1, L2, L3) or upstream power distribution points.
• Faulty input rectifier components within the drive causing internal voltage imbalance detection.
• Incorrectly sized input reactor (if present) leading to voltage sags under load.

Click steps to track your progress.

1. 1

   1. Measure the voltage between each pair of input phases (L1-L2, L2-L3, L3-L1) at the drive's input terminals using a true RMS multimeter.

2. 2

   2. Inspect all upstream fuses and circuit breakers for the drive's power supply, ensuring none are open or tripped.

3. 3

   3. De-energize and lock out the drive. Inspect the drive's input terminals (L1, L2, L3) and wiring for secure connections, corrosion, or signs of overheating.

4. 4

   4. Verify the power quality of the incoming utility supply at the main distribution panel, checking for stable voltage and phase balance.

5. 5

   5. If the drive has an input line reactor, inspect its connections and ensure it is correctly rated for the drive's power.