2014 年以来，电力设备需求回暖，再加上行业转型升级背景下高端领域投资明显增加，刺激行业固定资产投资增速回升。

A relay is used in electrical engineering to register overcurrent, overvoltage, reverse power flow, and over- and under-frequencies to avoid accidents or flashovers. It trips the circuit breaker when a fault is detected. If there is any discrepancy or abnormality in the current voltage or any other power measurement, the relay detects it and triggers an alarm. There are two types of relay: electromechanical relays and digital relays. Solid-state relays are electronic switching devices that operate on application of small external voltage across control terminals. Solidstate relays are smaller than electromechanical relays and are more reliable as they do not have moving parts.

A gearbox, as a part of the wind turbine, is used to step up the rotor speed such that it matches the generator speed. The gears connect the low-speed shaft to the high-speed shaft. The rotational speed of the generator shaft is far higher compared with the rotational speed of the turbine blades. The gearbox in the wind turbine does not change gears. It maintains a singlegear ratio between the rotation of the rotor and the generator. The gears convert low speed to high speed and high torque to low torque. This high-speed shaft produces electricity inside the generator.

Elevators and escalators are positioned in buildings for efficient movement of people and goods within a building's premises. Elevators and escalators are installed in commercial buildings residential buildings, mixed-used buildings, IT parks, hotels, restaurants, and retail outlets. They are also installed in public places to improve vehicle parking management.

A heat exchanger is a mechanical device that transfers thermal energy from one medium to another. The media are generally separated by a partition to stop them coming into contact with each other. They incorporate fins or corrugations to increase the surface area for enhancing the eat exchange process. Heat exchangers are widely used in industrial applications such as refrigeration, air conditioning, sewage treatment, and natural gas processing. The best example of a heat exchanger is the classic internal combustion engine. The engine coolant flows in a circular motion through the radiator coils and air flows past these coils to cool the engine

A solar collector captures solar energy and converts it into useful thermal energy. The thermal energy then produced is used for water heating and air heating. It is also used to generate electricity for residential and commercial users by the use of a DC-AC converter system. In a solar power plant, electricity is generated by heating a fluid, which is used to drive the turbine connected to an electrical generator. Two types of solar collectors are widely used: concentrating and non-concentrating solar collectors. Concentrating solar collectors use solar parabolic and Fresnel trough technology, central receiver systems, dish-engine systems, and solar updraft tower plants. Non-concentrating collectors are used in small-scale applications such as evacuated tube and flat-plate solar collectors, and unglazed water and air collectors.