In 550KV lines, the double circuit transmission line towers are often used, in the maintenance of one of the circuit, due to normal operation, the other line will have an electromagnetic induction and electrostatic induction. So, the earthing switch, which is used on the into line side and outlet side of the transformer substation or which is to match the disconnector, should have the ability to open and close the electromagnetic induction and electrostatic induction to some extent.

Since March 2005, our company started to research and develop such earthing switch, on December 30th, 2005, JW8B-550 earthing switch developed by our company passed all the test items in xi 'an high voltage electric institute. Its technical parameters is far higher than the international requirements, reached the international advanced, the domestic leading level.

The main technical parameters

Items	Specifications	Unit	Value
1	Rated voltage	kV	550
2	Rated frequency	Hz	50
3	Rated short-time withstand current	kA	3
4	Rated short-time resistance current duration	s	3
5	Rated peak withstand current	kA	10
6	Rated short-time power frequency withstand voltage (effective value)	kV	80
7	Rated lightning impulse withstand voltage	kV	1550
8	Rated operating impulse withstand voltage	kV	1175
9	Open and close electromagnetic induction current (rated induction voltage 35KV)	A	4000(international requirement 160A)
10	Open and close the electrostatic induction current (rated induction voltage 50KV)	A	50(international requirement 25A)
11	radio interference level	μV	≤2000
12	Rated terminal static mechanical load	N	Longitudinal 4000 Horizontal 2000 Vertical 1500
13	Mechanical life	time	3000
14	The maximum operating force of earthing switch	N	150
15	The operating mechanism of earthing switch		CJ11 electric mechanism
16	Opening and closing time	s	12±2
17	Installation direction of earthing switch		With the busbar parallel or vertical

JW5-550/363 type Disconnector

GW27-550/4000 type