CA2227933A1

CA2227933A1 - Phasing and indicator arrangements for switchgear or the like

Info

Publication number: CA2227933A1
Application number: CA 2227933
Authority: CA
Inventors: Gregory C. Mears; Brian P. Mugalian
Original assignee: S&C Electric Co
Current assignee: S&C Electric Co
Priority date: 1997-01-24
Filing date: 1998-01-26
Publication date: 1998-07-24
Anticipated expiration: 2018-01-26
Also published as: CA2227933C

Abstract

A phasing and indicator arrangement is provided for switchgear or the like that responds to electrical sources and provides voltage indicator functions, phasing determinations, and self-test features. Phasing provisions are responsive to two or more voltage sensors proximate respective electrical sources to provide an output that represents the phase difference, i.e. time relationship, between the electrical sources as an alternating-current voltage measurable by a voltmeter. The output is relatively independent of the voltage of the electrical sources. The indicator arrangement is operable in a test mode to test the integrity of one or more voltage indicators while clearly identifying that the indicator arrangement is in a test mode. In a preferred arrangement, the indicator arrangement in the self-test mode is powered by a photocell. Further, in the self-test mode, the indicator arrangement generates signals through each voltage sensor and over the complete voltage sensing path, the generated signals being substantially similar to the signals generated by each voltage sensor during normal operation in response to an alternating-current source. In the self-test mode, the phasing arrangement is also tested.

Claims

1. A phasing arrangement comprising first means for sensing two or more alternating-current electrical sources; and second means responsive to said sensing means for providing outputs that represent the phase of each of the electrical sources substantially independent of the voltage of the alternating-current sources such that the alternating-current voltage differential between the electrical sources is representative of the phase difference.

2. The phasing arrangement of claim 1 wherein said first means comprises voltagesensors that provide outputs that are sinusoidal waveforms representative of the electrical sources.

3. The phasing arrangement of claim 1 wherein said second means comprises third means for clamping said outputs of said voltage sensors.

4. An arrangement for providing phasing outputs for an electrical circuit that correspond to the phase of respective alternating current signals in the electrical circuit, the arrangement comprising sensing means responsive to the alternating current signals for providing sensed input signals and first means responsive to said sensed input signals for providing phasing outputs that respectively represent the phase of the respective alternating-current signals but which are substantially independent of the magnitude of the respective alternating current signals.

5. The arrangement of claim 4 wherein said first means comprises means for clamping said sensed input signals.

6. In an alternating-current voltage sensing system of the type where at least one voltage sensor provides a sensed output signal representative of the sensed voltage, wherein the improvement comprises first means responsive to the sensed output signal for providing a phasing output that is substantially independent of the sensed voltage but substantially represents the phase information of the sensed alternating-current signal.

7. The combination of claim 6 further comprising two or more voltage sensors, said first means comprising means for providing a phasing output corresponding to each voltage sensor such that the alternating-current voltage between said phasing outputs represents the phase difference between the respective sensed voltages.

8. A method for determining the phase relationship between two or more alternating current signals comprising the steps of:
sensing each of the alternating current signals to develop sensed sine-wave output signals;
transforming the sensed sine-wave output signals into respective substantially square-wave signals that are substantially independent of the magnitude of the alternating-current signals but that substantially accurately represent the phase relationships of the alternating current signals; and determining the phase relationship between the alternating-current signals on the basis of the alternating-current voltage measured between the substantially square-wave signals.

9. A method for verifying the phase relationship between two alternating-currentsignals comprising the steps of:
providing first and second signals as respective high-impedance, voltage-dependent signals representative of each of the alternating-current signals;
clamping each of the first and second signals to provide third and fourth signals that substantially accurately represent the respective phase information of the first and second signals; and determining the phase difference between the alternating-current signals via thethird and fourth signals.

10. The method of claim 9 wherein said determining step is accomplished by measuring the alternating-current voltage between the third and fourth signals.