Result
Preliminary calculation: This tool is for quick sizing and information. Electrical installation designs and cable and protection selection must be done according to the relevant standards and by an licensed electrical engineer. Results are approximate.
Formula
Imbalance % = ( largest deviation / average ) × 100Phase imbalance is caused by uneven distribution of single-phase loads, loose terminals, a faulty fuse, grid-related problems or phase loss. Unbalanced voltage causes negative-sequence currents in the motor and increases heating. That is why a compressor protection relay (phase sequence/loss) is important.
- Take the measurement under load and at the same time
- Check terminal and contactor contacts
- A phase sequence error also causes reverse rotation in the compressor
Frequently asked questions
How is phase imbalance measured?
Measure the three-phase voltage or current at the same time and find the percentage of the largest deviation from the average.
What does imbalance do to a compressor?
The windings heat up and vibration increases, life is shortened, and protection trips more often.
How is it fixed?
Distribute loads evenly across the phases, tighten connections, and notify the utility provider.