Hioki IR5050 - Use of GUARD Terminal; Measurement Unaffected by Surface Electrical Resistance

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Use of GUARD Terminal
3.6 Use of GUARD Terminal
Measurement una󰀨ected by surface electrical resistance
A GUARD terminal is used to prevent the surface electrical resistance of an insulating
material a󰀨ecting measurement, enabling correct measurement of the entire volume
resistivity of the material.
Current detector
Cable
Metallic shielding layer
Bare conductor
Insulating material
Core
Power supply
When testing the insulation of a cable, as shown in the diagram above, wind a bare
conductor around the surface of the insulating material and connect the conductor
to the GUARD terminal. This prevents the leakage current on the surface of the
insulating material owing into the current detector, which enables the actual
resistance of the entire volume of the insulating material to be measured.
HIOKI IR5050A961-00