Undervoltage

What does E.UVT mean?

This protective function activates, particularly with PM motors, when the converter voltage drops due to power supply issues like power failure or voltage sags. This causes the motor to coast, and if an automatic restart function is enabled, it may lead to repeated restarting and coasting cycles. Insufficient input voltage can prevent the inverter from maintaining stable operation and delivering rated power, potentially leading to inconsistent process control.

• Main supply voltage sag or complete power failure at the facility or specific branch circuit.
• Poor connection or loose wiring at the inverter's input terminals (R, S, T) causing voltage drop.
• Undersized power supply transformer or upstream wiring experiencing excessive voltage drop under load.
• Momentary loss of one or more input phases (e.g., from an upstream breaker trip or contactor chatter).

Click steps to track your progress.

1. 1

   Measure incoming AC line voltage at inverter input terminals (R, S, T) using a true RMS voltmeter and verify it is within the inverter's specified range (e.g., 380-480VAC).

2. 2

   Inspect and tighten all input power wiring connections at the main breaker, contactor, and inverter input terminals (R, S, T).

3. 3

   Check the capacity of the upstream power transformer and wiring to ensure it can support the inverter's rated current under full load.

4. 4

   Review inverter undervoltage trip level parameters (if adjustable, e.g., P7-01 undervoltage trip level) to ensure they are appropriate.

5. 5

   Monitor utility grid voltage stability using a power quality analyzer over a period to detect sags or interruptions.