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Transmission Lines Theory Testing and Commissioning Chapter | 6 77

FIGURE 6.11 Measurements of cable positive sequence impedance.

FIGURE 6.12 Measurements of cable zero sequence impedance.

6.4.9 Sheath Voltage Limit Test
At the cross-bonding link boxes, a nonlinear resistance is used to reduce the
induced voltage in the cable sheath during a fault condition to test the insula-
tion of the sheath voltage limit (SVL). Leave the three terminals of SVL
connected to earth and the other three terminals are then able to measure
each free terminal of the SVL. Record using the Megger tester after adjusting
to 1 kV DC for 1 minute. Then discharge the induced charge at all the free
terminals after each measurement. Restore the connection after test, as
shown in Fig. 6.13.
The insulation value of the SVL should be more than 1 GΩ at 1 kV.