Analysis on Development Space and Trend of High and Low Voltage Distribution Cabinet
Popularity：1010Date of publication：2022-10-11
The transformer industry in China started much later than that in developed countries. In the early days of the founding of the People's Republic of China, the development of the transformer industry in China was very slow, the production capacity of enterprises was insufficient, and domestic demand needed to be solved by imports. After the reform and opening up, due to the introduction of market competition mechanism, all transformer enterprises actively carried out system reform to adapt to the market economy, and China's transformer industry has been developing rapidly. However, due to the time and process required to adapt to the market economy, many domestic transformer manufacturers have slowed down the pace of research and development of new products and new technologies, and the talent training cannot keep pace, so the development capacity of transformer enterprises in China is very limited.
From the current development situation of China's transformer industry, although the scale of China's transformer industry is relatively large, the production capacity has also increased a lot compared to the past. However, compared with foreign large enterprises, China's transformers still lack competitiveness in the market. In addition, the transformer industry is a mixture of good and bad, and the supervision is not effective, which makes the phenomenon of shoddy goods often occur in the market, disrupting the market competition order, and also greatly damaging the image of China's transformer industry.
The power distribution cabinet, sometimes referred to as the power distribution box, is a cabinet that integrates the electrical components used for power distribution: air switch, circuit breaker, knife switch of various models, terminal blocks, protection equipment (thermal relay, time relay, fuse, etc., and advanced protection devices, etc.), measuring equipment (voltmeter, ammeter, frequency meter, power meter, etc., as well as transformers and various sensors).
Because of its good function, the power distribution cabinet is widely used in residential buildings, schools, hospitals and other domestic power distribution control. Some people may ask, why can't we see the power distribution cabinet? Because some power distribution cabinets are very small, most of them are concealed in the wall, and the larger ones are installed in the power distribution room, so it is rare to see power distribution cabinets in daily life. Power distribution cabinets, or power distribution boxes, such as lighting distribution cabinets and power distribution cabinets, are often seen in enterprise plants and workshops. Generally speaking, the power distribution cabinet is mainly divided into primary, secondary and low-level tertiary power distribution equipment.
The power distribution cabinet mainly has two functions: one is to distribute power and control the electrical equipment; the other is to provide power off protection in case of overload, short circuit and leakage of the circuit. When the circuit fails, it is conducive to controlling the fault range and quickly finding out the fault point and removing it in time, without large-scale power off. In addition, it is convenient to place various protective equipment in the power distribution cabinet, such as fuse (fuse) to prevent short circuit, air switch to prevent overload, etc., which can protect lines and electrical equipment. That is to say, things should be put together to facilitate maintenance and inspection. Especially in the case of large power consumption today, it is not feasible to have no power distribution cabinet, which greatly helps us to improve the convenience of power consumption.
The power distribution cabinet has a complex structure and large output circuit capacity. It is the power distribution center of the power supply system and will be installed in the substation to distribute electric energy to the secondary power distribution cabinet. The power distribution cabinet is divided into power distribution cabinet and motor control center. The application parts of the two are opposite. The power distribution cabinet is mainly used in the parts with few loops and scattered loads, while the motor control center is used in the parts with many loops and concentrated loads. It is mainly used to undertake the distribution of electric energy by the primary distribution cabinet and distribute it to nearby loads. The power distribution cabinets are mainly lighting distribution cabinets and power distribution cabinets. Their capacity is relatively small and their layout is relatively decentralized. They are mainly responsible for controlling the lowest level load distribution.
The safe use of high and low voltage distribution cabinets has always been the focus of attention, and the following precautions need to be understood. When working on a fully or partially charged panel, the maintenance equipment shall be separated from the operating equipment with obvious signs. When working on the secondary circuit of the running current transformer, it is strictly forbidden to disconnect the current circuit. In order to reliably short circuit the secondary coil of the current transformer, the short circuit piece and short circuit line must be used. It is prohibited to use the wire to wind. It is prohibited to carry out any work on the circuit and conductor between the current transformer and the short circuit terminal. Before the secondary circuit is powered on or withstand voltage test, the duty officer and relevant personnel shall be notified, and personnel shall be assigned to watch the site, check the circuit, and pressurize it after confirming that no one is working. The personnel checking the secondary circuit of the power failure protection box shall not conduct any switching operation without the permission of the personnel on duty.
However, the installation, acceptance, handover test run, operation and maintenance of high and low voltage distribution cabinets shall comply with the requirements of the power department. Attention should also be paid to the following matters: the user should carefully check the goods according to relevant regulations when receiving them, and the products that are not installed immediately should be stored in an appropriate place according to the normal use conditions. The product shall be lifted at the bottom with special slings. The product shall be horizontally placed on the prepared foundation, four anchor bolts shall be installed (secondary grouting method can be used), and then the gap between the product base and the foundation shall be plastered with cement mortar to prevent rainwater from entering the cable room. Connect the high and low voltage cables through the bottom sealing plates of the high and low voltage chambers. The gap between the cable and the pipe is sealed and waterproof.
Whether overhead incoming lines or cable incoming lines are used at the high voltage side of the high and low voltage distribution cabinet, obvious visible fractures (such as drop fuses) of the incoming lines at the high voltage side shall be set near the substation. This will clearly show the maintenance operator whether the substation is live or not. To ensure the safety of maintenance operators. After the product is installed in place, reliable grounding shall be made: the two main grounding terminals on the channel steel of the power station base, the neutral point and shell of the transformer, and the lower pile head of the arrester shall be directly grounded by the installation department. The grounding shall share a set of grounding devices, and the grounding resistance shall be less than 4 ohms. There shall be at least two grounding leads from the grounding grid to the product. When working on the secondary circuit of voltage transformer in operation, short circuit or grounding shall be strictly prevented. Insulating tools and gloves shall be used. If necessary, relevant relay protection devices shall be stopped before work. When connecting temporary loads, special switches and fuses must be installed.