My company switch between its main functions: automatic isolation in user side interphase short circuit fault, automatic removal of the user side grounding fault, and can be used to close the load current operation.

Boundary load switch with a built-in voltage transformer, a set of built-in current transformer; The CPU internal processor and communication module; With voltage during fault tripping judgment and fault memory; Have trip latch function.

Boundary load switch is applicable to 10 kV neutral point grounding, approved by arc suppression coil grounding or the 10 kV distribution line of low resistance ground system and user (including temporary users) boundary.

2.2 the main function

2.2.1 automatic removal of single-phase grounding fault

When the user side of single-phase grounding fault occurs, dividing line switch automatic brake, dump the fault feeder, ensure substation and feeder on other branches of the safe operation of the user.

2.2.2 short-circuit fault isolation and automatically

When the user side interphase short circuit fault occurs, boundary load switch in substation for protection tripping, break-brake dump fault line immediately. Substation outlet switch after reclosing, fault line isolation, make the other branches on the feeder users quickly restore power.

2.2.3 quickly locate fault point

User feeder switch, the boundary between failure only user power responsibility, and can take the initiative to report the fault information, make the electric power company can quickly clear the accident point, timely on-site processing, make the fault line as soon as possible to restore power.

2.2.4 monitor user load

Boundary load switch testing data can be transmitted power management center, achieve real-time monitoring of distant load.

2.3 boundary load switch fault handling

Boundary load switch fault handling methods are shown in table 2.

Table 2 line circuit breaker fault handling

 Three boundary load switch fixed value and substation protection setting for coordination with the problem

3.1 for the neutral point grounding or via arc suppression coil grounded system

Interphase short circuit current action constant value: should be considered reliable feeder through the maximum load current. Action time limit should be made to match the substation for the action time of the reclosing protection, before reclosing action, boundary load switch tripping.

Single-phase grounding current action constant value: the zero sequence current fixed value, according to line cross section and length, escape routes should be considered for capacitive current. Due to the neutral point grounding or via arc suppression coil grounding system, the single-phase grounding fault happens, transformer substation line protection tripping, signal grounding, only allowed to run short indirectly. In order to judge fault, and the boundary between the action of load switch time, should consider to avoid the instant grounding deadline, and action again after substation grounding signal trip, can choose 6 ~ 8 s.

3.2 for the neutral point via small resistance grounding system

Interphase short circuit current action constant value: same as above.

Single-phase grounding current action constant value: neutral point via small resistance grounding system, due to the transformer substation of 10 kV overhead line general configuration, two pieces of zero sequence protection for a period of 120 a, time limit of 0.2 s; Two 20 a, time limit for 1 s. Therefore, while dividing line zero sequence current of load switch fixed value and action time, should be made to match the substation zero sequence protection, 0 s.

In 4 load switch between running and maintenance problems should be paid attention to

Appearance should be regularly check the load switch between ontology and controller are in good condition; Boundary load switch state indicating whether it is right, whether running state energy storage; Boundary load switch lead spacing is in accordance with the code requirements; Each part connection fastening, do you have any overheating phenomenon; Grounding device in good condition, do you have any rust; Controller lights flashing warning.

Check whether dividing line load switch rotation or grounding resistance measuring whether extended, load switch between users in internal equipment installed and trouble-free, after the success of the substation feeder circuit breaker tripping overlap, should be timely organization find line fault points, break-brake found boundary load switch, it shall promptly report to the administrative departments of electric (dividing line switch, the controller failure indicator continue flashing 48 h).

Should be arranged regularly check for clearing dividing line load switch, inspection period and circuit board rod inspection cycle is the same. Operating more than 10 years in principle boundary load switch should schedule rotation maintenance.

5 installation boundary load switch problems should be paid attention to

Boundary load switch device can only be installed on the branch line or the end of the line, shall not be used string, as shown in figure 2.

Figure 2 boundary load switch installation schematic diagram

Load switch as the boundary between the first switch, power companies and users boundary load side joint users.

Installed boundary load switch ontology, relevant departments should organize before insulation resistance testing, and power frequency withstand voltage test and test; Insulation resistance measurement standards: use 2500 V wave measuring insulation resistance by megger, boundary load switch, relatively and fracture Ω 1000 M or higher. Power frequency withstand voltage test standard: boundary load switch, relatively and fracture: 42 kV 1 min (due to internal installation of boundary load switch TV, and do not do withstand voltage test). Boundary load switch points and the closing operation face surface should be toward the outside.

Boundary load switch controller is installed on the load switch body panel. Can be done through simple operation control of the switch.

6 what has been discussed above

Boundary load switch application in 10 kV line, greatly reduces the trouble-free line joint forced outage, narrowing the scope of failure blackout, shorten the blackout time users, thereby improving the user power supply reliability.

Boundary load switch is better solved the interphase short circuit occurred 10 kV substation, and quickly locate fault point when single-phase earth fault.