Axis
Meaning
X
Ambient temperature T
U
of the bushing
Y (left)
Power factor tan δ depending on the ambient temperature T
U
Y (right)
Change of main capacitance ΔC/ΔC
0
depending on the ambient
temperature T
U
If the measured capacity C deviates from the reference capacity C
0
after the temperature
correction, the main insulation may have suffered a partial breakdown.
The level of capacity deviation caused by a partial breakdown depends on the number of
inserts. The number of inserts rises with increasing voltage level and the capacity deviation
reaches the level of measuring accuracy of the capacity measurement.
Fig. 19: ΔC/ΔC
0
(U
m
)
Axis
Meaning
X
Voltage U
m
of the bushing
Y
Change of capacity ΔC/ΔC
0
depending on the voltage U
m
► If the capacity deviation indicates partial breakdowns, then:
▷
Take the bushing out of service.
▷
Contact HSP.
Range STARIS®-Sia+
45/53
