Testing electrical installations
AssigneeRobin Electronics Limited
InventorsArun Sehdev, Martin Litherland
Life of this patent
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Abstract
A main circuit loop tester includes a wave form generator for producing a current pulse in the form of a narrow spike. The wave form generator is connected to a power stage for producing a high amplitude output. The loop tester also includes a high frequency generator adapted to produce groups of low current pulses at high frequency. A measuring circuit is adapted to measure the resistive and reactive components of the resulting output signals from the main circuit. The tester is particularly useful for testing electrical installations which include residual current devices.
Claims16
A method of carrying out a loop test of a mains circuit having a residual current device, the method comprising:
- (a) applying a pulse to the mains circuit so as not to trip the residual current device, said pulse having a high peak current and a duration shorter than required to trip the residual current device;
- (b) measuring a voltage drop during the pulse;
- and,
- (c) calculating loop impedance as a function of the voltage drop.
A method of carrying out a loop test of a mains circuit including a residual current device, the method including the steps of:
- (a) applying a signal to the mains circuit being tested, said signal including a number of narrow pulses of high peak current value, wherein successive pulses are separated by sufficiently long intervals such that the residual current device is allowed to settle between pulses;
- and,
- (b) injecting a signal of low amplitude that contains frequencies significantly higher than a mains frequency so that an output signal is distinguishable from the mains frequency;
- whereby both resistive and reactive components of impedance are measurable.
A mains circuit loop tester comprising a waveform generator, for producing a current pulse in the form of a narrow spike so as not to trip a residual current device;
- a power stage for producing a high amplitude output;
- and measuring circuitry for measuring the resistive component of loop impedance as a function of an output signal from the mains circuit.
A main circuit loop tester including a high frequency generator adapted to produce groups of low current pulses at high frequency so as not to trip a residual current device, and measuring circuitry for measuring the reactive component of loop impedance as a function of an output signal from the main circuit.
A main circuit loop tester including a waveform generator for producing a current pulse in the form of a narrow spike so as not to trip a residual current device, which is connected to a power stage for producing a high amplitude output;
- a high frequency generator adapted to produce groups of low current pulses at high frequency;
- and measuring circuitry adapted to measure the resistive and reactive components of the resultant output signals from the mains circuit.
A method of carrying out a loop test of mains circuit including a residual current device, the method comprising:
- (a) applying a signal of low amplitude containing frequencies significantly higher than a mains frequency so as not to trip the residual current device, where by an output signal is detectable in the presence of the mains frequency;
- and,
- (b) determining an impedance component of the mains circuit based on the output signal.
The method according to claim 11, wherein the signal is applied for a number of successive cycles so as to allow transients in the system to decay, and thus to allow voltage and current phase angles of the signal to be measured.
A method of measuring loop impedance for a mains circuit having a residual current device, the method comprising the steps of:
- (a) applying two signal components to the mains circuit so as not to trip the residual current device, said two signal components including:
- a first signal component having one or more current pulses of sufficient amplitude to otherwise trip the residual current device but for the pulses being of sufficiently short duration and sufficiently spaced apart in time, and a second signal component having an amplitude insufficient to trip the residual current device and having a frequency substantially higher than a frequency of the mains circuit such that an output signal resulting therefrom is detectable in the presence of the mains frequency;
- and,
- (b) determining both a resistive component and a reactive component of the loop impedance for the mains circuit from output signals responsive to the two applied signal components.
Dependencies are inferred from the claim text.