Single-phase rotary phase converters contain two wires, labeled L1 and L2. Three-phase rotary phase converters contain three wires, labeled L1, L2, and L3. The voltage between each wire should always be roughly the same. Imbalances occur when the voltage between one or more wires is significantly higher or lower.

Here are the two main scenarios in which this imbalance occurs:

• The voltage from either L1 to L3 or L2 to L3 in a three-phase rotary phase converter falls or jumps.
• A significant voltage difference occurs between L1 and L2 of a single-phase rotary phase converter.