Power transmission lines are generally divided into two types: overhead lines and cables. Overhead lines are composed of copper or aluminum wires along with steel wires to support their weight, forming a steel core aluminum stranded wire. Since the insulation safety distance from the ground for 110kV lines is usually above 10 meters and for 220kV and 330kV lines it is even higher, the lines must be overhead to ensure insulation. Cables, on the other hand, are covered with insulating materials and can be touched by hands, so they are placed underground.

1. Protection device - A set of hardware equipment that issues alarm signals or trip commands to terminate the development of faults or events that endanger the safe operation of power systems or power components (such as generators, lines, etc.) when faults occur in the power system or when events occur that threaten the safe operation of the power system. Devices that protect power components are called relay protection devices; those that protect the power system are called safety automatic devices. This regulation collectively refers to protection devices. 1.2 Line protection - Two sets (or more) of longitudinal protection (including protection channels), backup distance and zero-sequence protection. 500kV lines also have overvoltage protection and remote tripping devices. 1.3 Short-line protection - One half-breaker

Dongguan Xinzhou Mechanical and Electrical Air Conditioning Engineering Co., Ltd. is a construction unit that specializes in the design and installation of various mechanical and electrical engineering projects, including factory high/low voltage power distribution projects, central air conditioning system projects, purification and ventilation projects, water supply and drainage system projects, group telephone and network system projects, closed-circuit monitoring system, etc. The company also develops various scientific energy-saving renovation projects to help customers reduce energy costs; assisting in enhancing the comprehensive competitiveness of customers is the ideal choice for strategic partners of related enterprises.

The main reasons are as follows: 1. Poor insulation between silicon steel sheets; 2. Short circuit between some silicon steel sheets in the magnetic circuit; 3. Insulation damage of the through-core bolts or clamps, the upper yoke iron and other parts, resulting in short circuit; 4. Loose silicon steel sheets in the magnetic circuit creating air gaps, increasing magnetic resistance; 5. Short circuit in the coil due to inter-turn or parallel branch shorting; 6. Different number of turns in each parallel branch; 7. Incorrect calculation of the ampere-turns of the winding.

The rapid rise of the household central air conditioning market has attracted many home appliance enterprises to join the competition. Major home appliance giants such as Midea, Gree, and Haier have also set their sights on this huge market of household central air conditioning. Besides, foreign brands like McQuillan, Trane, Daikin, York, and Mitsubishi Heavy Industries are also paying more attention to their home central air conditioning businesses. According to the data, the overall scale of household central air conditioning in 2014 was approximately 15 billion yuan, an increase of 36% compared to 2013. It can be predicted that in the future, household central air conditioning will become the main force in the air conditioning market. In recent years, the product line of household central air conditioning has been continuously improved.