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Application of Huichuan MD320 frequency converter in 20t gantry crane of Railway Bureau freight yard

gantry crane is a kind of lifting and handling equipment used to lift, put down and carry heavy objects, and make them move horizontally within a certain distance. It has important applications in the production process

the traditional speed regulation methods of gantry crane, such as: wound rotor asynchronous motor rotor series resistance speed regulation, thyristor stator voltage regulation speed regulation and cascade speed regulation, have the common disadvantage that wound rotor asynchronous motor has collector ring and brush, which requires regular maintenance. The faults caused by collector ring and brush are relatively common, coupled with the use of a large number of relays and contactors, resulting in a large amount of on-site maintenance and a high failure rate of speed regulation system, Moreover, the comprehensive technical indicators of the speed regulation system are poor, which can no longer meet the special requirements of industrial production

AC variable frequency speed regulation drive has the following characteristics

a. it can realize stepless speed regulation of ordinary asynchronous motor

b. small starting current reduces the capacity of power supply equipment

c. start smoothly, eliminate the impact of machinery, and protect mechanical equipment

d. it can protect the motor and reduce the maintenance cost of the motor

e. it has significant power saving effect

due to the above characteristics of AC variable frequency speed regulation transmission technology, it has begun to replace DC speed regulation device and become the development direction of modern electrical transmission The speed regulation principle is as follows: after inputting three-phase AC from the power end to the frequency converter, it is converted into DC through rectification and filtering, and then converted into three-phase AC with adjustable frequency and voltage through the electronic switch circuit, and then output after filtering as the input power of the motor

China's cranes began to use frequency converters for speed regulation control in the late 1980s. At that time, most of them were frequency converters controlled by v/f ratio. The characteristics of variable frequency stepless speed regulation, such as stability, controllability and energy saving, provided a new scheme for large-scale and high-quality speed regulation of gantry cranes driven by AC asynchronous motors. It has high-performance speed regulation index, can use squirrel cage asynchronous motor with simple structure, reliable operation and convenient maintenance, and is efficient and energy-saving. Its peripheral control circuit is simple, the maintenance workload is small, the protection and monitoring function is perfect, and the operation reliability is greatly improved compared with the traditional AC speed regulation system With the continuous development of frequency conversion technology, professional crane manufacturers have also turned their attention to this high-tech field, and carried out in-depth research on frequency conversion speed regulation system according to the characteristics of crane operation. Therefore, the use of AC variable frequency speed regulation is the mainstream of the development of AC speed regulation technology for gantry cranes

secondly, the basic and application instructions of PLC and the Humanized Interface Design of the touch screen enable each operator to quickly adapt to and master the operation habits of the car, up to 86 operation screens and fault information query screens, so that the maintenance personnel can quickly find out the cause of the fault and eliminate it

II. Electrical structure of 20t gantry crane

this paper introduces the application of Huichuan frequency converter and Mitsubishi PLC in a 20t gantry crane in a freight yard subordinate to Zhengzhou Railway Bureau:

the rated lifting capacity of the crane is 20t, lifting height: 11 meters, lifting speed: 10 meters/second, crane speed: 47.9 meters/second, Trolley Speed: 45.2 meters/second, span: 18 meters, effective cantilever 6.5 meters

main hook motor 1 6-pole variable frequency motor 45 enhance the ability to deal with trade protectionism kW

crane motor 4 8-pole ordinary asynchronous motors 7.5kW

trolley motor 2 6-pole ordinary asynchronous motors 11kw

I) the main components of the electrical system are composed of Huichuan MD320 series inverter, Mitsubishi FX1N series PLC, and Tianjin Luosheng human-machine interface

1) selection of frequency converter

the frequency converter is used to drive the asynchronous motor for speed regulation. Generally, the frequency converter should be selected according to the rated current of the asynchronous motor, or according to the current value (maximum value) in the actual operation of the asynchronous motor. Generally, the rated current of the frequency converter should be ≥ (1.05 ~ 1.10) the rated current of the motor or the maximum current in the actual operation of the motor. In the crane industry, especially for the safety of the lifting mechanism, the selected electrical capacity is much larger than the rated capacity of the equipment Therefore, when selecting the main hook motor frequency converter, its capacity should be amplified

the main hook motor is a 6-pole variable frequency motor, which operates with constant torque in the range of 3 ~ 50Hz and constant power in the range of 50 ~ 100Hz. The model of main hook frequency converter is md320t-75kw

the crane motor is an 8-pole motor, 7.5kW; the model of crane frequency converter is md320t-45kw

the model of trolley motor is a 6-pole motor, 11kw; the model of trolley frequency converter is md320t-37kw

PLC select two 60 point PLCs, namely fx1n-60mr Pws-6600 is selected as the touch screen, "said adabel, global market manager of DSM optical fiber and cable materials department." all low-voltage appliances adopt Schneider imported devices

its basic block diagram is as follows:

block diagram interpretation

this electrical system uses two PLCs as the data and logic processing core of the whole system, which mainly has the following advantages:

A) the program of the whole system is divided into main hook program and cart program, which is convenient for debugging. The running state of the cart and cart is transmitted to plc0 through coding program, and then displayed on the touch screen

b) highlights the centralization of the system: centralized monitoring, centralized operation, centralized management

C) highlights the decentralization of the system: decentralized control, decentralized danger, decentralized load

d) the touch screen is composed of more than 80 pictures, including the operation status of the system, speed display, system testing, fault frequency records, historical fault records, and troubleshooting methods

2. System layout

the system is composed of four cabinets: power cabinet, lifting frequency conversion cabinet, large and small vehicle frequency conversion cabinet, resistance cabinet

the lifting frequency conversion system uses a PLC to control the lifting and lowering of the main hook frequency converter, and communicates with the touch screen As shown in the figure:

size then connect the two to the upper beam. The upper system is installed in a cabinet and shares a PLC, in which the PLC encodes the running state of the crane and trolley, the limit signal, etc. and connects it with the PLC input in the lifting cabinet, so that it can be displayed on the touch screen As shown in the figure:

the resistance cabinet is placed outside the power distribution room for outdoor installation because it needs to absorb the regenerative energy of the frequency converter, which is heated and has a high temperature

in order to ensure the heat dissipation of components in the cabinet, each cabinet is equipped with two axial flow fans for heat dissipation The fixed asset investment is no less than 2billion yuan, and the distribution room is also equipped with air conditioners for heating and cooling

in the design process, the following problems should be considered:

1) anti slip hook when the main hook rises or falls

in the electromagnetic brake hold

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