Safety requirements for substation and distribution installations
All electrical equipment used for power receiving, substation and distribution, such as switchgear, control equipment, protection equipment, metering devices, bus bars and other auxiliary equipment, etc., are collectively referred to as substation and distribution devices.
1. Metering device.
1. Metering device for measurement.
For high-voltage or low-voltage users with high-voltage or low-voltage switchgear, the metering device should be installed on the incoming switchgear, and the watt-hour meter should be installed on the small screen panel of the switchgear or in the observation hole of the watt-hour meter on the small screen panel. There is no incoming switch cabinet can be installed on the watt-hour meter board or distribution board, the watt-hour meter board is generally installed on the reliable and dry wall downstairs, should be as close as possible to the entry point, its surrounding environment should be clean and bright, easy to install, disassemble, maintain, meter reading, the center of the watt-hour meter from the ground height in 14~1.8m.
2. The incoming and outgoing wires of the watt-hour meter should meet the following requirements:
The incoming and outgoing wires of the watt-hour meter shall be insulated with copper core, and shall not be insulated with aluminum core or flexible wire;The minimum cross-section, the voltage loop shall not be less than 15mm2, the current loop shall not be less than 25mm2；The insulation must be good, and there must be no joints;When the inlet and outlet lines of the surface-mounted watt-hour meter are threaded, steel pipes or hard plastic pipes should be worn respectivelyThere shall be no joints in the inlet and outlet lines of the watt-hour meter, the voltage circuit and the secondary current circuit.
Second, the busbar. The bus bar is a conductor used to collect and distribute current, and there are hard bus bars and soft bus bars. In the substation and distribution devices of general industrial enterprises, hard busbars are used more.
1. Hard busbars are usually made of aluminum or copper bars. According to A, B, C three phases are coated with yellow, green and red paint, which is not only easy to identify, but also can play an anti-corrosion role. The bus bar should be arranged in a certain order, and the bus bar is generally arranged up and down, and the three phases of A, B and C are arranged from top to bottomThe three phases A, B, and C arranged horizontally are arranged from the inside to the outside;Down leads, A, B, C three phases from left to right.
2. The cross-sectional area of the bus bar should meet the requirements of load current and mechanical strength, and should also withstand the impact test of time-dynamic stability and thermal stability of short-circuit faults. For the sake of safety, a certain distance should be maintained between the busbar, between the bus and the grounding body, between the bus and other devices, the higher the voltage, the greater the distance.
3. The bus bar can be connected by three methods: welding, crimping and lapping. The connection between copper and aluminum should be connected by copper and aluminum transition joints. The connection of the bus bar should strive to be in good contact, if the contact resistance is too large, the joint may overheat and cause an accident.
4. The soft bus is mostly used outdoors. The connection of the soft bus bar should be connected by special wire clamps or crimping, and general soldering should not be used. The soft bus bar must not have joints in the pitch. It should be noted that the soft bus bar should not be too tight or too loose.
3. Other issues.
1. Whether it is an indoor or outdoor substation and distribution device, there are generally a lot of exposed live parts. Such as connecting wires, busbars, isolation switches and other devices, are generally exposed. To prevent arc burns or scalds from molten metal splashes, the parts that may generate arcs should be isolated. In order to prevent erroneous access to live parts during maintenance, permanent or temporary protective barriers should be set up between the equipment of different lines.
2. For the power distribution device installed in the workshop or public place, it is advisable to adopt a protective structure. If the structure is open, appropriate fencing or fencing should be added. The height of the mesh barrier should not be less than 17m, the lower edge should not be more than 0 above the ground1m, the mesh should not be larger than 40x40mm2. The distance between the mesh fence and the bare conductor should not be less than 0 for low-voltage substation and distribution devices15m, for 10kv installation should not be less than 035m。The height of the indoor fence should not be less than 12m, outdoor should not be less than 15m。For low-voltage installations, the distance between the fence and the bare conductor should not be less than 08m。
3. In addition to maintaining a certain distance between the parts of the indoor substation and distribution device, the layout of each part must also be conducive to the convenience of maintenance work and maintain sufficient maintenance channels. The width of the front channel of the low-voltage distribution device should generally not be less than 1 when the single row is arranged5m；When arranged in two rows, it should not be less than 2m. The width of the channel behind the low-voltage distribution device should generally not be less than 1m, and the difficulty should not be less than 08m。The clear height of the back channel should not be less than 19m, 2 on the channelWhen there are bare conductors below 2m, they should be protected. For high-voltage power distribution installations, these distances must be increased. When the total length of the complete power distribution device is greater than 7m, there should be two outlets, and the width of the outlet should not be less than 08m, and the distance between the two exits should not be greater than 15m.
4. The substation and distribution room should be able to prevent five defenses and one pass. These five defenses are fireproof, waterproof, leak-proof, wind-proof, snow-proof, and anti-small animals;One pass is to ensure good ventilation.
5. The door of the substation and distribution room and the substation and distribution device should be open outward. The substation and distribution room are built of non-combustible materials. Batteries and other equipment with burning and high risk should be installed in isolation. When the battery is charged, hydrogen is released, and in order to prevent it, special attention should be paid to the good ventilation of the battery room.
6. The busbar of the power distribution device should also be painted with yellow, green and red colors according to A, B and C. The secondary line of the power distribution device shall be insulated copper wire with a voltage level of not less than 500V, and the cross-section of the voltage circuit shall not be less than 15mm2；The cross-section of the current loop shall not be less than 25mm2。
7. In order to avoid accidents caused by lack of concentration, the necessary interlocking device should be used.
Appropriate interlocking devices should be installed between the circuit breaker and the disconnector, between the switch of the power capacitor and its discharge load, and on the door of some restricted areas.
In order to avoid accidents caused by lack of concentration, indicator lights or other signaling devices can also be used. In addition, various warning signs or signs should be hung as needed.
8. In addition to qualified safety appliances such as insulating rods, insulating pads, insulating boots, insulating gloves, electroscopes, etc., the substation and distribution room should also be equipped with fire-fighting equipment, first aid kits, flashlights and other utensils.