Working Principle:

1. The variable frequency transformer section adopts the low-voltage dual-splitting method to obtain two sets of three-phase power sources with a phase difference of 30 degrees. A static screen is installed between the high and low voltages, and the insulation level of the low-voltage coil is increased to the 10kV voltage level to meet the higher common-mode voltage generated by the secondary side frequency conversion rectifier device. The power supply transformer is placed in the explosion-proof chamber of the main transformer to provide control power for the frequency converter.

2. The high-voltage switch is equipped with an isolation switch and a circuit breaker to disconnect the control power and load current. The main power source adopts a PLC comprehensive protection system for monitoring and fault isolation, while the auxiliary transformer uses fuses for overcurrent protection.

3. The low-voltage switch adopts a dual-circuit design and uses two sets of PLC comprehensive protection systems for mutual monitoring and detection, completing equipment operation monitoring and fault isolation.

4. The high and low voltage switches communicate with the downstream frequency converter simultaneously to achieve phase closure lock and interlock functions, avoiding equipment damage due to operational errors.

Mine explosion-proof switch

1. It is equipped with an imported industrial Programmable Logic Controller (PLC) and Human-Machine Interface (HMI) to form the core control system: stable performance, precise protection, and easy maintenance.

2. Utilizes the HMI screen for displaying operational status, electrical parameters, and faults. The interface is a fully Chinese LCD. Parameters can be set within the HMI screen with password lockout functionality.

3. Continuous current adjustment with a stepping value of 1A.

4. Independent compartments for circuit breaker, isolating switch, and connection enabling live maintenance and ensuring safe and reliable operation and maintenance.

5. Features compact size, rational structure, intuitive operation, and dual electric/manual stored energy closing mechanisms.

6. Comprehensive protection functions include overload, short circuit, overvoltage, under voltage, leakage, leakage lockout, phase loss, overtemperature, wind power gas lockout, and emergency stop of upstream power supply. And also protection fault feedback from the low-voltage side of the mobile substation.

7. The PLC intelligent protection system includes self-diagnosis, fault diagnosis, inspection, and memory functions. Real-time detection and digital display of operational status and fault indications facilitate system operation, maintenance, diagnosis, and handling.

8. Modular design with standard RS232/485 communication interface, providing powerful remote communication and control capabilities.

9. All faults are disconnected by the signal line driving the high-voltage side vacuum circuit breaker, thereby reducing the breaking current and overcoming the dead zone problem where faults cannot be disconnected between the low-voltage winding of the transformer and the low-voltage switch circuit.

10. The protection box is divided into four circuits on two sides, meeting the requirements for multiple load connections.