Abstract: A loop resistance tester (LRT) for shield integrity testing comprising three elements: a “drive” current coupler, a “sense” current coupler, joint probes, and an instrument assembly. A low-power excitation current is sent from the instrument into the drive coupler, which is essentially a transformer. This induces a current in the electrical cable under test, as long as that cable and the connected structure form a continuous current path, or loop. This induced loop current is detected by the “sense” current coupler (transformer) and is measured by the instrument. The ratio of the loop voltage to loop current, as phasor values, gives the complex loop impedance, the real part of which is the loop resistance.

Abstract: A ferroresonant regulator for use in an inductively coupled high frequency power distribution system. A constant current resonant power source, comprising a sine wave oscillator (12), an amplitude controlled amplifier (16), a power amplifier (20), and an impedance matching transformer (24), provides current at a frequency of 38 kHz to a supply loop (68) that is installed in the floor of an aircraft passenger space. A current sensing transformer (32), and a voltage sensor (46) produce feedback signals that are used to control the amplitude of the current circulating in the supply loop, maintaining it substantially constant. A plurality of multiturn coils (70) are disposed proximate the supply loop. Connected to each of the multiturn coils is a saturable transformer (76), which includes a secondary winding attached to a load comprising an entertainment and passenger service system installed in each seat. A tertiary winding (106) on the saturable transformer is connected across a resonance capacitor (108).