METHOD FOR MEASURING INSULATION RESISTANCE OF CABLE OR ELECTRIC EQUIPMENT

PURPOSE:To measure insulation resistance without working the neutral point of a grounding transformer by connecting the ground resistance of the intermediate metallic layer of the case of a cable shield layer or electric equipment to reference resistance and thus forming a bridge circuit. CONSTITUTI...

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Bibliographic Details
Main Authors SHIRAHAMA OSAMU, MIZUNUMA ISAO, UMEDA SUSUMU, NIIMOTO TAKASHI
Format Patent
LanguageEnglish
Published 27.09.1988
Subjects
MEASURING
MEASURING ELECTRIC VARIABLES
MEASURING MAGNETIC VARIABLES
PHYSICS
TESTING
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Summary:PURPOSE:To measure insulation resistance without working the neutral point of a grounding transformer by connecting the ground resistance of the intermediate metallic layer of the case of a cable shield layer or electric equipment to reference resistance and thus forming a bridge circuit. CONSTITUTION:The layer consisting of an insulating layer 24 - an intermediate metallic layer 20 - an insulating layer 28 is provided between the cable shield layer 16 and an iron wire armor 26 in case of a submarine cable. At this time, the intermediate resistance 64 is the resistance of the insulating layer 24, the ground resistance 68 is the resistance of the insulating layer 28, and a filter circuit 70 is connected thereto. Then a variable voltage source 84 is adjusted so that a bridge balance voltage detecting meter 88 indicates zero, thereby canceling a noise voltage developed across a resistance 82 for detection. Then a switch 78 is closed to apply a voltage to the bridge circuit and a proportional resistance 72 and an adding/subtracting resistance 74 are adjusted so that the bridge balance voltage detecting meter 88 indicates zero, thereby finding insulation resistance RX 40.
Bibliography:Application Number: JP19870065466