PF-451 F&F phase switch

For cooperation with contactors. Without priority phase. With adjustable lower and upper tripping threshold.
Automatic phase switch is used to maintain continuity of power supply to a single-phase load in case of loss of one of the supply phases or a drop of parameters below normal.

Operation
The switch in direct connection is used to supply a single-phase circuit whose load does not exceed 16 A. For circuits with a load of more than 16 A, we use an arrangement of the switch and three contactors with appropriately selected load capacity.
A three-phase voltage (3×230 V+N) is supplied to the switch input (L1, L2, L3, N). A single-phase voltage (230 V AC), i.e. the phase voltage of one of the phases, is directed to the switch output (T1, T2, T3). The electronic circuit of the switch controls the voltage values of the supplied phases. The phase with the correct parameters is directed to the output. The order of switching of phases is not specified. The phase with the best parameters is always directed to the output. After a decrease in the value of the parameters of this phase, there will be a switchover to the next good phase. The switching time (appearance of voltage at the output) after the disappearance of the currently switched phase is from 0.5 to 0.8 s (during this time the consumers are not powered). The Uk input is used to control the switched voltages. The circuit allows only one phase to be switched on. This protects against simultaneous application of voltages of two phases to the output, which could cause a phase-to-phase short circuit. Also, if the contactor is damaged (e.g., a break in the coil circuit or burning of the operating contact), it will switch the load to another phase, even though the voltage is correct on the phase. If the contactor contacts are permanently short-circuited, the system will not switch to another contactor, despite the incorrect voltage on that phase. After switching on the supply voltage (at least one phase) for 2 seconds, the system examines the correctness of the connected voltages and only after this time will switch the phase to the output. The switch has the ability to set the lower (150 V to 210 V) and upper (230 V to 260 V) voltage threshold at which switching will occur. LEDs are used for visual signaling: green - power supply; yellow - phase switched on at the output.