3.2 Measuring Insulation Resistance
78
G terminal grounding is used for measuring
the insulation resistance between the core
and the metallic shielding layer of a high-
voltage cable with the cable connected to
other high-voltage equipment. The diagram
below shows an example of measurement.
Rc: Insulation resistance of the insulating
material of the high-voltage cable
(Between core and metallic shielding
layer)
Rs: Insulation resistance of the sheath of
the high-voltage cable
(Between metallic shielding layer and
ground)
Rn: Insulation resistance between insulator
or high-voltage equipment and ground
Influence of Rs and Rn is removed and
solely Rc is measured.
Reference
High-voltage power receiving
facility code 2002
Measurement using G (GUARD)
terminal grounding
Meter transformer
Disconnector
Load
Core
R
n
Rc
Rs
N
Remove
Grounding
P
Power supply
wire
Cable
Power
supply
side
side
wire
Metallic shielding layer
of the cable
Current
detector
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