Explosion-proof distribution box internal wiring, today Zhejiang Fulu explosion-proof technology mainly talk about the installation and use of explosion-proof distribution box need to pay attention to the seven things to facilitate everyone's use, so as to avoid unnecessary trouble.
Seven things:
1. Before installing and using the product, check whether the technical data on the nameplate is consistent with the usage.
2. Before the installation and maintenance must be cut off before the power supply;
3, in and out of the cable through the rubber seal, must be pressed with washers and compression nuts, to ensure that the seal and the cable can not be loose;
4, the use of seal rings in the process of corrosion, embrittlement, deformation, sticky or hardness changes in more than 20% of the factory should be promptly purchased and replaced to the manufacturer to ensure that the explosion-proof performance is reliable;
5, maintenance and demolition pay attention to the explosion-proof surface must not bump, scratch, corrosion, and regularly coated with 204-1 anti-rust oil;
6. The distribution box should be inspected regularly during use to ensure its good operation;
7, non-professionals are strictly prohibited open cover maintenance and inspection. 
Second, the wiring considerations:
Explosion-proof distribution box is a total circuit distribution box for all users. The distribution box is a mass parameter on the data. It generally constitutes a low-voltage electrical connection according to the electrical wiring. The switchgear, measuring instruments, protective electrical appliances and auxiliary equipment are required to be assembled in enclosed or semi-enclosed metal cabinets or screen panels to constitute low-voltage distribution. box. During normal operation, the circuit can be switched on or off by means of a manual or automatic switch.
1 Causes of Electrical Failure of Explosion-Proof Distribution Boxes 1.1 Faults Caused by Product Quality In the rural power grid reconstruction, due to the large number of distribution boxes required and the short construction period, the time required for the delivery of the low-voltage electrical equipment in the distribution box factory was acute. The large number of products has led to the phenomenon that the requirements for product quality are not strict, causing some products to fail shortly after being put into operation. If some types of AC contactors were put into operation shortly after the distribution box was put into operation, they could not be operated because the contactor closing coil was burned out.
1.2 Failure caused by improper selection of electrical equipment in explosion-proof distribution box Because the AC contactor capacity is not properly selected during manufacture, AC contactors of the same capacity are installed for different outlet circuits and the three-phase load imbalance is not taken into account. The situation that the current rating of some of the outlet contactors could not be selected on the basis of the normal selection model, and the selection of a current level was improved, resulting in the occurrence of AC contactor burnout in the summer hot season.
2 Improvement plan of the explosion-proof distribution box 2.1 The protection circuit is used to prevent the external circuit failure caused by the power supply of the distribution box. Choose a small-sized intelligent phase loss protector, such as the optional DA88CM-II motor phase loss protection module (Shanghai products) installed in the distribution box to prevent the motor from being burned out due to low-voltage phase-to-phase operation.
2.2 Select energy-saving AC contactor (similar to CJ20SI type) products, and pay attention to the AC contactor coil voltage connected to the corresponding terminal block of the selected remaining current protection device, pay attention to the correct load matching. When selecting AC contactors, products with insulation class A and above shall be used, and the rated current of the main circuit contact shall be guaranteed to be greater than or equal to the load current of the controlled line. The electromagnetic coil of the contactor has a rated voltage of 380V or 220V and the coil can be used within the range of 80% to 105% of the rated voltage.
2.3 Selection of residual current action protector. The products that meet the standards of GB6829 "General Requirements for Residual Current Operation Protectors" and have been qualified by the China Electrotechnical Products Certification Committee must be selected. Alternative LJM (J) series power-saving type and low sensitivity time-delay protectors are available. The protection device shall conform to the national standard GB13955-2005 "Installation and operation of residual current protection device". Leakage protection device breaking time, when the leakage current is rated leakage current, the action time should not exceed 0.2s.
2.4 The low-voltage cables are used for the incoming and outgoing cables of the distribution box. The selection of cables should meet the technical requirements. For example, for the distribution box of 30kVA and 50kVA transformers, use the VV22-35x4 cable for the power distribution box, the VLV22-35x4 cable of the same specification for the branch line, and the VV22-50 for the line of the 80kVA and 100kVA transformer box. ×4, VV22-70×4 cable, branch outlets use VLV22-50×4, VLV22-70×4 cables respectively, the cable is crimped with the copper-aluminum connection nose and then bolted to the wiring pile head in the distribution box .
2.5 fuse (RT, NT type) selection. The rated current of the low-voltage side overcurrent protection fuse of the distribution transformer shall be greater than the rated voltage of the low-voltage side of the distribution transformer, generally 1.5 times of the rated current. The rated current of the melt shall be in accordance with the overload tolerance and fuse allowed by the transformer. Determine the characteristics of the device. The rated current of the fuse of the outlet circuit over-current protection fuse shall not be greater than the rated current of the total over-current protection fuse. The rated current of the melt shall be selected according to the normal maximum load current of the circuit and should avoid the normal peak current. The rated current of the shunt capacitor bank fuse can generally be selected according to the capacitor rated current of 1.5 to 2.5 times.
Inquiry instructions:
A. Explosion-proof distribution box Explosion-proof grade: 1.IIB grade 2.IIC grade B. Explosion-proof box Installation method: 1. Hanging installation 2. Floor type (vertical) installation C. Explosion-proof lighting box inlet and outlet ways: 1. Under Into the next 2. Into the out 3. Into the out 4. In the next D. Explosion-proof power box Corrosion level: 1. Indoor installation 2. Outdoor: a.WF1 (rain cover) b.WF2 (protection cabinet )
E. Explosion-proof switch box component brand:
1. No requirement (general use Zhengtai brand)
2. Imported components (usually Schneider)
3. Customized according to the requirements of the user
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