The connection mode of low-voltage capacitor bank of fire lighting distribution box is improved, and the installation position of low-voltage capacitor bank is changed from the pile head on AC contactor to the connection between low-voltage incoming line of distribution box and electricity meter.

To prevent inaccurate measurement of metering device due to capacitor circuit open phase or capacitor damage during operation. In addition, bsmj series capacitor should be selected to ensure reliable component quality and safe operation.

Select energy-saving AC contactor (similar to cj20si type) products, pay attention to the connection between the coil voltage of AC contactor and the corresponding terminal selected as current action protector, and pay attention to the correct load matching.

When selecting AC contactor, the products with insulation grade of a or above shall be selected, and the rated current of main circuit contactor shall be greater than or equal to the load current (1) The main distribution box, distribution box and switch box shall be set in the construction power distribution system, which shall be arranged according to the sequence of "main distribution open" to form a "three-level distribution" mode.

(2) The installation position of all distribution boxes and switch boxes in the construction power distribution system shall be reasonable. The main distribution box shall be close to the transformer or external power supply as far as possible to facilitate the introduction of power supply. The distribution box shall be installed in the central area where the electrical equipment or load is relatively concentrated as far as possible to ensure the balance of three-phase load. According to the site conditions and working conditions, the installation position of the switch box should be as close as possible to the electrical equipment controlled by the switch box.

(3) Ensure three-phase load balance of temporary power supply and distribution system. The power supply and lighting power supply at the construction site shall form two power supply lines. The distribution box and lighting distribution box shall be set separately.

(4) All electrical equipment on the construction site shall have its own special switch box.

(5) The cabinet and internal setting of distribution boxes at all levels shall comply with safety regulations. The purpose of switchgear shall be indicated, and the box shall be numbered uniformly. The power supply should be cut off and the door should be locked when the power distribution box is out of use. The fixed distribution box shall be fenced and provided with rain proof and smash proof measures.

6. The difference between distribution box and distribution cabinet. According to the precautions in GB / t20641-2006 "General requirements for empty shells of low voltage switchgear and control equipment", we can see that not only the box door is missing, but also the switch is still in the "open" state. A total of six cables were exposed without any warning. As the distribution box is located 50 meters north of the South Station of Hangtian bridge, in the southeast corner of the roundabout, there are many people coming and going, and the traffic is also very heavy.