110 kv and above crosslinking cable composition of common grounding system
1。 Grounding box
short cable line, it is only in the side of the cable line terminal the metal sheath are connected and the grounding box, not metal sheath grounding end insulation by maintaining box and the earth.
2。 Maintenance earthing box
in order to reduce the metal sheath or insulation joint on both sides of the baffle plate protects the impulse voltage of the suite, where should be the sheath grounding between the client and the earth, or between the insulation joint partition installed overvoltage device maintenance, now generally use zinc oxide valve maintenance. Maintenance device installed in crossover interconnection kit and maintenance.
3。 Cross connect box
a long cable line, in different phase of metal insulation will joint connected to cross cross method, metal sheathed by cross interconnection box transposition.
4。 Grounding cable ( Ground wire) Choose
( 1) Insulation: grounding line under normal operation conditions. Should maintain the same standard of insulation and sheath, with a tolerance of 10 kv dc voltage 1 min no breakdown of the insulation properties.
( 2) Cross section selection: considering the high voltage cable system is directly grounded system, short circuit current is larger, grounding line should be chosen section 120 mm, or more copper insulated wire.
110 kv cable grounding box is mainly used to monitor cable insulation to ground, such a high voltage is not directly connected to grounding box, usually over voltage may be current transducer for the connection between them, the effect of the transmitter is in accordance with the design requirements to reduce the high pressure side of the voltage or current, with the expansion of power grid coverage, high voltage power cable engineering, high voltage cable grounding method or not directly related to the safety of the power system safe and stable operation.