---
lang: "en"
title: "PF-451: Automatic Phase Switch"
sku: "PF-451"
canonical_url: "https://shop.marcomweb.it/en/voltage-current-phase/pf-451-automatic-phase-switch"
brand: "MARCOM S.r.l."
end_of_life: "false"
---

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PF-451: Automatic Phase Switch

## Product Description

With phase “Priority”. For cooperation with contactors. With adjustable lower (170 ÷ 210V) and upper (230 ÷ 260) activation threshold. Automatic phase switches serve to maintain continuity of power supply to single-phase receivers in case of power phase decay or a drop of its parameters below standard values.

## Operation

The directly connected switch is used for supplying a single-phase circuit whose current load does not exceed 16A. For circuits that have a current load greater than 16A, a configuration consisting of a switch and three contactors that have a properly selected current load capacity is used. Three-phase voltage (3x230 V + N) is supplied to the input of the switch (L1, L2, L3, N). Single-phase voltage (230 V AC), which means phase voltage from one of the phases, is directed to the output of the switch (T1, T2, T3). The electronic system of the switch controls voltage values of supplied phases. The phase with correct parameters is switched to the output of the switch. The phase switching sequence is not specified, the phase with the best parameters is always switched to the output. The switching to another phase with correct parameters occurs only after a drop of parameter values of the currently used phase. The switching time (required for voltage to appear at the output) after the decay of a currently activated phase is between 0.5 and 0.8 sec. (during this period receivers are not supplied). The UK input is used to control activated voltages. The system allows the activation of only one phase. This prevents the simultaneous switching of voltages from two phases to the output. Such simultaneous switching of voltages could lead to a phase-to-phase failure. In addition, the contactor defect (e.g. a break in the coil circuit, suspension or burning of the operating contactor) will cause the receiver to switch to another phase despite the fact that the voltage in a given phase is correct. If the contactor contacts are permanently closed, the system will not switch to another contactor despite the fact that the voltage in this phase is incorrect. After the activation of the supply voltage (at least one phase), the system examines the correctness of supplied voltages for 2 seconds and only after that time the system switches the phase to the output. The switch offers the possibility of adjusting a lower voltage threshold (from 150 V to 210 V) and an upper voltage threshold (from 230 V to 260 V) at which switching occurs.

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Source: https://shop.marcomweb.it/en/voltage-current-phase/pf-451-automatic-phase-switch

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