Publish Time: 2022-08-05 Origin: Site
AC motor frequency conversion speed regulation has become the trend of contemporary motor speed regulation, with small size, light weight, large torque, high precision, strong function, high reliability, simple operation, easy communication and other functions. It is better than any previous speed regulation methods, such as pole change speed regulation, voltage regulation speed regulation, slip speed regulation and so on. Therefore, it is widely used in all walks of life, such as nonferrous metals, petroleum, petrochemical, chemical fiber, textile, electric power, machinery, building materials, coal, medicine, papermaking, injection molding, cigarettes, cranes, urban water supply, central air conditioning and sewage treatment industries.
Overview of loads in this project
Shenzhou flying saucer is a common amusement equipment. Its rotating mechanical turntable is driven by two motors, one is responsible for driving the 2.2-ton turntable to rotate, and the other is responsible for the turntable sliding left and right on the track. The drive motor that slides left and right uses the large inertia of the machine itself. The motor is forward and reversed combined with the speed of the free sliding of the turntable, and at the same time drives the turntable to accelerate and slide down for a short time, so that it reaches a new high point for reciprocating motion. Usually, the whole experience takes three minutes.
The variable frequency drive communicates with PLC;
Large inertia, quick start;
The short-term start-up current has a large impact, and the start-up current is more than twice the rated motor current;
Frequent forward and reverse start;
✔ In the SVC vector mode, the inverter can output large torque to drive the large inertia load (0.3Hz/150%) in the low frequency state;
✔ The dynamic performance is stable and the response speed is fast, which is suitable for frequent forward and reverse start-up occasions;
✔ With high-performance current vector algorithm, the motor can reach the best speed in 0.5 seconds, and the output current is controlled within the range of 2 times the rated current. Compared with the power frequency startup, the current is 6 times smoother, the working current is greatly reduced, and the energy saving effect is obvious ;
✔ It has complete overcurrent, overvoltage and overload protection equipment for reliable operation;
✔ Compact size, convenient installation and simple operation.
1. The installation method of VFDs in the control cabinet
In the practical application of variable frequency drives, it is necessary to install multiple low-power VFDs in the same control cabinet. In order to reduce mutual thermal influence, it is generally recommended to place them side by side. If it is required to be installed vertically, in order to reduce heat dissipation adverse effects, partitions should be added between the variable frequency drives.
2. Temperature requirements
The general requirement is 0 to 55°C, but in order to ensure the safety and reliability of the VFD during operation, it is best to control it below 40°C during use. The lower limit of the ambient temperature is usually 0°C or –10°C, assuming that there is no condensation. In the control cabinet, the inverter is generally installed on the upper part of the cabinet, strictly abide by the installation requirements in the product manual, and never allow the heating element or the easy-to-heat element to be installed close to the bottom of the inverter. When the ambient temperature changes greatly, condensation is likely to occur inside the inverter, which will reduce its insulation performance and may even cause a short circuit accident. If necessary, add desiccant and heater to the control cabinet.
High-power variable frequency drives also need to install fans in the control cabinet, and the air ducts should be designed reasonably. All air inlets should be equipped with dust-proof nets to ensure smooth exhaust, so as to avoid the formation of eddy currents in the cabinet and cause dust accumulation. Select the matching fan according to the ventilation volume in the AC drive manual, and pay attention to the vibration-proof problem in its installation.
3. Anti-vibration and shock
When the control cabinet of the variable frequency drive is subjected to mechanical vibration or shock, it will cause poor electrical contact. Try to improve the mechanical strength of the control cabinet and keep it away from the shock source. If necessary, use anti-vibration rubber pads to fix components such as electromagnetic switches in the control cabinet that may generate vibration.
4. Anti-electromagnetic interference
The instrument and electronic system in the VFD control cabinet should use metal casing to shield the electromagnetic interference of the inverter to the instrument. In addition, the connection between electrical components and instruments should be shielded control lines, and the distance between the busbar and the power line should be kept at least 100mm.
5. Protection requirements
Waterproof:
If the frequency inverter is placed on site, it should be noted that there should be no pipe flanges or other water leakage points above the inverter control cabinet, and there should be no splashing water near it, and the protection level of the inverter cabinet should be above IP43.
Dustproof:
All air inlets should be equipped with dustproof nets to prevent flocs from entering, and the dustproof nets should be detachable to facilitate cleaning. The grid of the dust-proof net is determined according to the specific situation of the site, and the junction of the surrounding of the dust-proof net and the control cabinet should be handled strictly.
6. Grounding of variable frequency drive
Correct grounding is an important means to improve system stability. The grounding resistance of the grounding terminal of the frequency inverter should be as small as possible. The cross-sectional area of the grounding wire should not be less than 4mm2 and the length should not exceed 5m. The grounding of the inverter should be separated from the grounding point of the power equipment and not shared.