The BXJ series Mining Explosion-proof and Intrinsically-safe Low-Voltage Protection Box for Mobile Substation (hereinafter referred to as Protection Box) is mainly used at the low voltage side of the mining explosion-proof mobile substation in the power supply system with rated voltage of 3300V, 1140V, 660V, rated frequency of 50Hz, rated current to 1250A and three-phase AC neutral point indirectly grounded. It can pair with the KJG Mining Explosion-proof and Intrinsically-safe Permanent Magnet High-voltage Vacuum Switch that is manufactured by our company to control the mobile substation. It has short circuit, overload, electric leakage, electric leakage locking, overvoltage, under-voltage, phase failure and other protection functions.
1) See the following table for basic parameters
Model | Rated Current A | Rated Voltage V | Frequency HZ | Working System |
BXJ-800/3300Y | 800 | 3300 | 50 | Long-term |
BXJ-630/3300Y | 630 | 3300 | 50 | Long-term |
BXJ-1250/1140 (660)Y | 1250 | 1140 (660) | 50 | Long-term |
BXJ-630/1140 (660)Y | 630 | 1140 (660) | 50 | Long-term |
Good explosion-proof performance, advanced technologies, stable and reliable protection performance, compact structure, easy for maintenance and overhaul.
I. Structural Features
The overall structure of the protective case consists of the explosion-proof primary chamber and wiring chamber.
1. The explosion-proof primary chamber consists of the front door, chamber, rear explosion-proof flange, etc.
a) The front door is provided with an easy-to-observe Chinese display window and operation buttons such as closing, opening, resetting, overloading, leakage, shifting, confirming and adjusting.
b) The chamber is equipped with PLC protection devices and various protection signal sampling components.
c) The explosion-proof flange at the rear of the explosion-proof chamber can be subject to flange connection with the wiring chamber of the mobile substation (dry-type transformer).
2. Three terminals of the main circuit and two seven-core terminals for control loop wiring shall be installed in the wiring chamber. There are two pressure plate cable lead-in devices at the left and right sides of the wiring chamber respectively, two M42 compression nut lead-in devices are installed in front of the wiring chamber, which can be used for external control wiring.
3. The door opening mode of the protective case has a quick opening door structure with a safety mechanical locking device.
a) Release locking before door opening, turn off the switch to cut off the power supply, the vacuum circuit breaker at the high voltage side is tripped, then the next operation can be conducted.
b) After the door is closed, it can be powered.
4. The full Chinese backlit LCD is adopted in the protective case, and parameter setting, data monitoring, historic record query and other operation can be conducted through the operation buttons those are installed on the front door.
II. Electrical Features
The Three-phase current signal, system voltage signal and additional DC voltage signal are directly connected to the PLC. The PLC analyzes and processes the digital signals of three-phase current, system voltage and insulation resistance according to the parameters preset, so as to complete short circuit, overload, electric leakage locking, leakage protection, overvoltage, undervoltage and other protection actions.
The protective box sends the signal of normal and abnormal operation at the low voltage side to the high voltage side of the switch through closing and opening of PLC output relay Q0.0, so as to realize control of the mobile substation.
1. The elevation height shall not exceed 2,000m (0.08~0.11MPa);
2. Ambient Temperature -5℃ to +40℃ (23°F to 104°F);
3. The surrounding relative humidity should not exceed 95% (25°C/77°F);
4. Places without strong vibration and shock;
5. Places where rain, snow, and drips can be prevented;
6. The installation inclination with the horizontal plane shall not exceed 15°.
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