Automatic Phase Selector Controller Possibilities
The Universal Automatic Electronic Phase Selector Controller (single-phase automatic throw-over switch) is designed to supply an industrial/equipment single phase 220-240V/50Hz load from three phase four wire mains 3 x 380/415 + N in order to maintain uninterrupted power supply of essential single-phase loads and protect them against un-allowable voltage variations in the mains. For this purpose, a single-phase load is switched into a three phase circuit. Depending on voltage presence and voltage quality on phases the PEF-301 will automatically select the optimum phase and promptly switch the single phase load supply to this phase. A phase prioritization is foreseen, i.e. the device restores the supply circuit to the user-selected priority phase after switching to reserve phases and regenerating the voltage on the priority phase.
Depending on voltage presence and voltage quality on phases, the Phase Selector Controller will automatically select the optimal phase and promptly switch the single phase load supply of any wattage to this phase. The phase selector is a microcontroller based digital device. User should make setting of trip threshold limits of the controller – the minimal and maximal voltage values at which it conducts changeover (or switches over to another phase). Phase L1 has the highest priority. It means that at normal parameters of voltage on all phases connected to the controller (L1>L2>L3), the load will always be energized from phase L1. If on L1 the value is out of limits set by user, it switches the load to the nearest by priority phase in not more than 0.2 seconds if the its voltage corresponds to the normal level. If the voltage on the reserve phases does not correspond to the trip set limits the load switches off. After the load had been switched to another phase and the voltage parameters had been restored on the priority phase, the load will be switched back to the priority phase in return time ‘r’ (from 5 to 200 sec, settable) set by user. If ‘r’ is in the position “∞”, the return to the priority phase will not be performed.
L1, L2, L3 can be 3 phases of the same line or can be 3 separate power sources with common/grounded neutral. In this case the phase selector controller acts as auto changeover switch between the 3 sources of power. The illustration below shows how this action is performed.