Operation process:

(1) Connect the main circuit: when the knife switch is closed, the green indicator light will be on. When the normally active button SB1 is pressed, the magnetic force will be generated when the attracting coil is charged, so that the main contact km will be closed and the main circuit will be connected. The auxiliary contacts KM1 and km2 will be closed together, KM3 will be separated, the green indicator light will be off, and the red indicator light will be on. Then, SB1 bounces back and KM1 sticks to the circuit through the auxiliary contact in parallel with the self sticking circuit.

(2) Shut down the main circuit: press the normally closed start button SB2, the power of the attracting coil is cut off, the moving iron core is sprung up by the tension spring, the main contact km is separated, the main circuit is disconnected, the auxiliary contacts KM1 and km2 are separated, KM3 is closed, the red indicator light is off and the green indicator light is on.

4.2 reform the self-locking circuit in the control circuit

According to the principle of CJX2 AC contactor, we made the following adjustments to its control circuit: discard the auxiliary contact KM1 with small touch area, then adjust the orientation of SB1 and SB2, and then lead out a connecting line from the middle orientation of SB1 and SB2 to connect to the A-phase outgoing terminal, and install a switch s on the connecting line to facilitate maintenance.

Operation process:

(1) Connect the main circuit: close the knife switch and switch s, the green indicator light will be on. When the button SB1 is pressed, the magnetic force will be generated when the attracting coil is electrified, so that the main contact km will be closed, the main circuit will be connected, the auxiliary contact km2 will be closed, KM3 will be separated, the green indicator light will be off, and the red indicator light will be on. Then, SB1 bounces back, and the self adhering circuit is composed of a phase main contact with a large touch area and a new connecting line, and the circuit is connected.

(2) Shut down the main circuit: press the normally closed start button SB2, the power of the attracting coil is cut off, the moving iron core is sprung up by the tension spring, the main contact km is separated, the main circuit is disconnected, the auxiliary contact km2 is separated, KM3 is closed, the red indicator light is off, the green indicator light is on, after the SB2 is sprung up, manually open the switch s.

5 function view

In April 2015, we reformed the control circuit of two CJX2 AC contactors. After 8 months of operation in the high humidity and dust environment, no fault has occurred.

The main contact replaces the auxiliary contact and insists on self-locking circuit, which eliminates the fault of CJX2 AC contactor caused by the small area of auxiliary contact. The fault rate is reduced from 0.25 times / month to 0 times / month now. The effect is remarkable. We exceeded our expectations.

Economic benefits: in 2015, the average load of the two pilot stations was 115KW. After the self-locking circuit transformation, it was roughly estimated that six defective power outages caused by poor touch of CJX2 AC contactor were reduced. According to the calculation of one-hour power outage, the multiple power supply energy = 115 × 6 × 1 = 690kw. H, and the additional operating income was 690 × 0.56 = 386.4 yuan according to the residential lighting electricity price. If it is carried out in a suitable area, the economic benefits will be considerable.

In terms of power supply reliability rate, because each station area has cut 6 hours of blackout time, the power supply reliability rate has been improved by 0.068%, and the power supply reliability rate has been further improved. To a certain extent, the impact of faulty blackout on users' production days has been reduced. To do a good job in providing quality service guarantee.

After this group activity, the academic atmosphere of suburban branch bureau was enriched, and the technical level of group members was improved. It has laid an excellent foundation for the next activity of our group.

In order to consolidate our activity, we adopt the following measures:

1) We will implement it in the suitable area to reduce the failure rate of CJX2 AC contactor and improve the reliability of power supply.

2) We notice that after the improvement of the control circuit, if the knife switch is continuously opened, only the main contact of CJX2 AC contactor is disconnected. When the circuit is disconnected, the A-phase outlet terminal of CJX2 AC contactor is connected to the c-phase power supply through the attracting coil, and it is still charged. For the sake of safety, the switch s installed on the connecting line must be turned over during maintenance.

3) After improvement, the problem of auxiliary contact affected by the environment is solved, but other parts and equipment will also be affected by the bad environment, resulting in problems. Therefore, it is still necessary to control the temperature and humidity of the power distribution equipment, clean up the dust in time, prevent the direct corrosion of corrosive gas, and improve the small environment of equipment operation, so as to ensure the safe and stable operation of the equipment.

After this activity, we learned that: there will be some new problems in the operation of electric equipment under different conditions, which requires us not to follow the rules. We should constantly develop and innovate, choose new ideas and new methods to deal with the problems, so as to make the electrical equipment operate better and provide high-quality power services for users.