| 摘要 |
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.
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