The construction elevator is an indispensable important construction equipment in modern high-rise construction with large tower crane. Especially in the construction of high-rise and super high-rise buildings, it plays an irreplaceable role in ensuring the construction period and safety, reducing the construction cost and reducing the labor intensity. At the same time, it is also an important symbol of construction team equipment level. According to the general experience, each tower crane for high-rise building should be equipped with at least one construction elevator. This paper introduces the good performance and energy saving effect of LD series frequency converter in building construction elevator.

Brief introduction of common elevator in construction
1. Control system
The control system is the key part of the construction elevator, which determines the performance of the whole machine. The rising, descending and stopping functions of ordinary elevator are realized by contactor relay control. Moreover, the speed is single and the impact of starting and braking is large, which damages the structure and mechanism seriously, and the electrical components are easy to be damaged, and the running speed is relatively low, which not only affects the construction speed, but also affects the benefit of construction enterprises. If the speed is simply increased, the acceleration will be too large and the impact on the structure and mechanism will be too large, which will accelerate the wear of gear rack and brake disc, thus reducing the reliability of operation.
2. Starting and braking system
The starting of ordinary elevator is to adopt direct starting or star delta step-down starting. The impact is very big, causing serious damage to the motor and electrical components. At the same time, the materials in the elevator are easy to fall, especially some construction site elevators still have the phenomenon of passengers. There is a great potential safety hazard. The brake of ordinary elevator is forced by mechanical brake. When the elevator suddenly drops from high speed to zero speed, due to the effect of inertia, not only the structure and mechanism are damaged, but also the materials inside the elevator are easy to fall, which also has certain security risks.

Advantages of frequency conversion system
1. Soft start
Compared with the power frequency starting mode, the frequency converter control can reduce the vibration and impact of the mechanical part, save the maintenance cost for the user, and the operation is stable.
2. Smooth braking
With the brake unit, the braking is stable and accurate, without "sliding" phenomenon.
3. High starting torque
High performance control mode is adopted, the torque is adjustable, and stable high output torque is provided in low frequency band.
4. Security
The advanced modern AC frequency conversion speed regulation technology is used to transform the electric drive system of the elevator, so that the motor can realize stable operation, improve the operation efficiency, improve the overload operation, eliminate the impact of braking, reduce the electrical maintenance and reduce the power consumption. At the same time, it has over-current, over-voltage, under voltage and input phase loss protection, as well as inverter over temperature, overload, motor fault protection and so on. Stepless speed control technology effectively solves the transmission impact of the mechanism, and prolongs the service life of gears, rollers, bearings and racks. Due to the current limiting function of the frequency conversion system, the impact current on the power grid when the motor is started is reduced, the mutual influence between the electrical equipment is alleviated, and the current carrying capacity of the cable is greatly improved. The power supply cable does not need to be enlarged, but can be reduced compared with the constant speed elevator. It not only saves the cost, but also creates convenience for retracting and releasing cables.

LD series frequency converter for elevator electric drive system technical transformation, not only to enhance the safety and reliability of the equipment, in the process of starting and stopping, almost can not feel the impact between the mechanical systems, greatly improve the stability and comfort of the elevator operation process, and save a lot of electric energy for enterprises and society, and greatly improve the work efficiency.