Thread Content
I. Structure and principle of the positive-pressure explosion-proof electrical control cabinet: The main body of the electrical cabinet consists of a positive-pressure electrical cabinet, a positive-pressure gas circuit system, an explosion-proof electrical box, and other components. The enclosure of the positive-pressure electrical cabinet is a airtight shell made from cold-rolled thin steel sheets through folding and welding. It can maintain the pressure of the internal protective gas at a level higher than that of the surrounding explosive gas environment, thereby effectively preventing external explosive gas mixtures from entering the enclosure. The positive pressure air circuit system is located below the positive pressure electrical cabinet. It allows compressed air or other non-flammable gases present on site to be depressurized and turned into pure, low-pressure gases that are then introduced into the positively pressurized electrical cabinets. After a 30-minute purging process, any explosive gases within the cabinets are removed, and the positive pressure is maintained, thereby ensuring that the interior of the electrical cabinets remains a safe environment. The flameproof electrical box is responsible for supplying power to the positive-pressure electrical cabinet. Power is supplied to the positive-pressure electrical cabinet once it has been purged for 30 minutes and the pressure inside the cabinet exceeds 70 Pa. Several cable entry devices are arranged on the outer wall of the flameproof electrical box ； Connect to the power cable, output cable, and cable for the explosion-proof master controller respectively. On the side of the electrical cabinet, there are several threaded connector holes, which are respectively: the inlet for compressed air or other non-flammable gases, and the outlet for gas from the positive pressure chamber. Several threaded connector holes are provided on the partition of the electrical cabinet; these are respectively: the power cable inlet, the output cable outlet, and the spare cable outlet. These threaded connectors are designed for users to use when installing cable and steel pipe wiring as well as gas supply pipes on-site. II. Operating Method of Positive Pressure Explosion-Proof Electrical Control Cabinet 1. The operating procedure for this electrical cabinet is very simple. Introduce compressed air ； Turn on the power to the explosion-proof electrical box; the power indicator light will turn on ； When the pressure in the electrical cabinet exceeds 70 Pa, pressing the start button on the flame-proof electrical box causes the positive pressure control system of the electrical cabinet to automatically enter the purging mode, and the ventilation indicator light turns on. After 30 minutes of purging, the operation indicator light turns on, and at the same time the positive pressure electrical cabinet begins to operate normally. 2. During normal operation, the status indicator light on the flame-proof electrical box is on; the positive pressure air supply system in the electrical cabinet operates in a closed-loop mode, ensuring that the internal pressure of the electrical cabinet remains between 70 Pa and 400 Pa. When there is a fault in the air supply line and the pressure inside the positive pressure electrical cabinet falls below the specified operating range of 150 Pa, the red light on the panel lights up to alert the duty personnel to take action ； When the pressure inside the positive-pressure electrical cabinet falls below 70 Pa+, the system will automatically cut off the power supply to that cabinet in order to prevent any risk of explosion. 3. When the positive pressure system is restarted, the system will operate again following the above steps, with timing starting from the purge phase. 4. Fault Condition: This electrical cabinet has been adjusted upon leaving the factory; therefore, it can operate normally without any adjustments during normal operation. However, during the operation of the electrical cabinet, if the red indicator lights on the control panel often light up, it is due to too low air pressure in the air supply system. This issue can be resolved by adjusting the throttle valve following the steps below. 5. Loosen the lock nut of the throttle valve, and turn the adjustment knob counterclockwise by half a turn or a little bit ； Observe the reading on the air circuit pressure gauge and check the alarm light; if the gauge reads around 150 Pa and the red indicator light on the panel stops flashing, it indicates that the adjustment was successful. Tighten the locking nut of the throttle valve. If the pressure gauge does not indicate around 150 Pa, or if the red indicator light on the panel continues to glow, repeat the above steps until the red indicator light on the panel stops glowing.