Power supply with two AC voltages - which selectively supply ohmic load having two coupled coils combining fluxes for control parameter of change-over switch

摘要

The power supply has two alternating voltages, which can be supplied to an ohmic load selectively. It is used for heating the glass of railway signalling equipment. The supply current is passed through an inductance. The flux is used to control a monitoring circuit to ensure the supply remains within a predetermined limiting value. There is a second coil (Z) coupled to the first coil (S) such that the total flux of the two coils is equal to that produced by the current when the alternative voltage is applied across the first coil. The ohmic load (V) is connected to the supply via a changeover switch (U).