Infeed: Voltage dip in at least one line supply phase

What does 206205 mean?

This alarm indicates a voltage dip or overvoltage in one or more line supply phases during operation, causing pulses to be inhibited for at least 8 ms. The operating signal of the infeed unit remains active, but pulse inhibition is displayed. The specific cause (e.g., line angle deviation, active current deviation, line overvoltage/undervoltage, peak current trip, or line asymmetry) is detailed by the alarm value in r2124. If unresolved, this can lead to unstable drive operation and potential damage to components due to irregular power supply.

• Sudden, heavy load increase on the same supply network (e.g., large motor starting) causing a momentary voltage sag below threshold.
• Loose connection or high resistance in one or more line phases at the main contactor, fuses, or input terminals of the infeed unit.
• Under-dimensioned main power supply transformer or distribution cabling unable to handle peak current demands.
• Temporary fault in the utility grid causing brief voltage drops below the infeed unit's minimum threshold (e.g., 340V for a 400V system).
• Incorrect setting of the undervoltage monitoring threshold parameter (e.g., P0850) for the infeed unit, making it overly sensitive.

Click steps to track your progress.

1. 1

   1. Measure the line-to-line voltage at the infeed unit's input terminals (e.g., L1, L2, L3) using a true RMS voltmeter during operation to detect dips.

2. 2

   2. Inspect and tighten all power connections in the main distribution panel, including fuses, circuit breakers, and infeed input terminals (e.g., U1, V1, W1).

3. 3

   3. Monitor the utility grid voltage using a power quality analyzer to identify external voltage sag events and their duration.

4. 4

   4. Verify the infeed unit's undervoltage threshold parameters (e.g., P0850, P0851) against the nominal supply voltage and application requirements.

5. 5

   5. Check the sizing of input reactors or chokes if present (e.g., L1, L2, L3 series reactors) for proper impedance and integrity.