Ammeter for grid system transmission lines - has oscillator with ferromagnetic crystal affected by conductor's magnetic field

摘要

An ammeter for grid system transmission lines has meter readings are transmitted by a sender. The latter (11) has an oscillator (13) whose frequency determining element (12) is an iron-yttrium garnet single crystal magnetically coupled with the highest voltage conductor. Its frequency is a function of magnetic field. A receiver (14), outside the range of magnetic field, has a frequency discriminator converting received frequency changes into amplitude fluctuations proportional to the measured current intensity. This arrangement enables measurements to be made from installations inaccessible during working. The readings have good linearity. The oscillator (13) is so tight that it can be fitted directly to the grid system conductors.