The phase control unit is used in cases when the power supply is three-phase, all three phases are regulated (three single-phase QUANT regulators are installed) and either all three-phase load (or part of the load) requires a clear exclusively three-phase power supply. This must be monitored to avoid damage or malfunction of the equipment.
The phase control unit is not required for three-phase loads that is not demanding to phase imbalance, phase alternation (rotation sense) and/or presence of all phases (3 of 3); for example, powerful heaters, which are loaded on three phases to equalize the currents in the neutral conductor. It is better to connect such consumers directly to the outputs of the regulators, because they do not need a tripping protection, and can continue to operate in case of such deviations.
The phase control unit does not need to be used with single-phase loads. Lighting, computer equipment and other similar loads must be connected directly to the output of QUANT regulators. If more reliable connection is necessary, even in case of disappearance of one or two phases, it is necessary to use additionally the phase selection relay.
At the request of the customer and at their personal discretion, it is possible to reduce the cost of the phase control unit approximately to 30%, having replaced Schneider Electric automatic equipment with an E.Next automatic equipment.