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I-beam cantilever crane
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FAQ
Under normal circumstances, it is not allowed. Above 60Hz (there are also modes above 50Hz), with constant voltage, it generally has a constant power characteristic. When the same torque is required at high speeds, attention must be paid to the selection of the motor and inverter capacity.
Power can still be output below 6Hz, but depending on conditions such as motor temperature rise and starting torque, the minimum operating frequency is set around 6Hz. At this point, the motor can output rated torque without causing serious heating issues. The actual output frequency (starting frequency) of the inverter varies by model, ranging from 0.5 to 3Hz.
When the frequency decreases, the voltage is reduced in direct proportion. Since the AC impedance decreases while the DC resistance remains unchanged, this will tend to reduce the starting torque at low speeds. Therefore, at low frequencies, to achieve a certain starting torque, the output voltage should be increased somewhat when V/f is given. This compensation is called enhanced starting. Various methods can be used to achieve this, including automatic methods, selecting V/f modes, or adjusting potentiometers.
When the frequency decreases, the voltage V also decreases proportionally. This issue has been explained in answer 4. The proportional relationship between V and f is predetermined considering the motor characteristics, and several characteristics are usually stored in the controller's storage device (ROM), which can be selected using a switch or a dial.
Using a frequency converter for operation, the frequency and voltage increase correspondingly with the acceleration of the motor, and the starting current is limited to below 150% of the rated current (depending on the model, it can be 125% to 200%). When starting directly with a power frequency supply, the starting current is 6 to 7 times higher, which can cause mechanical and electrical shocks. Using a frequency converter allows for a smooth start (the starting time is extended). The starting current is 1.2 to 1.5 times the rated current, and the starting torque is 70% to 120% of the rated torque; for frequency converters with automatic torque boost function, the starting torque can exceed 100%, allowing for full load starting.
When the frequency decreases (low speed), if the output power remains the same, the current increases, but under the condition of constant torque, the current remains almost unchanged.
The torque of the motor is generated by the interaction between the magnetic flux and the current flowing through the rotor. At the rated frequency, if the voltage is constant and only the frequency is reduced, the magnetic flux becomes too large, the magnetic circuit saturates, and in severe cases, it can burn out the motor. Therefore, the frequency and voltage must change proportionally, meaning that while changing the frequency, the output voltage of the inverter should be controlled to keep the magnetic flux of the motor constant, avoiding weak magnetism and magnetic saturation phenomena. This control method is often used in energy-saving variable frequency drives for fans and pumps.
The main circuit of the inverter can be roughly divided into two categories: the voltage type, which converts the DC of a voltage source into AC, with the filtering of the DC circuit done by capacitors; and the current type, which converts the DC of a current source into AC, with the filtering of the DC circuit done by inductors.
Product Introduction
Product Introduction:
Wall-mounted Jib Crane
▪ The wall-mounted jib crane is an economical heavy load solution.
▪ The wall-mounted jib crane provides good working coverage within a nearly circular working area and can be used with lifting devices such as tool balancers, pneumatic balancers, vacuum lifting tools, and hoists.
▪ Currently, the wall-mounted jib cranes supplied domestically are made of steel, with a maximum lifting capacity of 5 tons and an arm length of up to 7 meters, capable of achieving 200° of rotating lifting operations. An electric rotation mode can be selected for precise and easy positioning.
▪ The wall-mounted jib crane can be installed on the existing walls of the factory or other supporting structures, using a single tie rod design, with all components bolted together for easy installation and adjustment, making it lightweight for relocation.
Product Features:
▪ Easy to install;
▪ Single tie rod, both ends with right-hand threads for easy leveling;
▪ All components, including the trolley stop, are bolted connections.
▪ Lightweight: The ultra-light cantilever combined with copper bushings and high-strength brass graphite allows for easy rotation and precise positioning.
▪ Safety: The seamless, one-piece formed bracket components provide strong safety assurance.
▪ Full rated load: The pre-designed electric hoist considers 15% of the jib crane's rated lifting capacity as the total weight of the hoist and hoist trolley, and 25% as impact load, ensuring efficient utilization of the jib crane's lifting capacity.
Product Applications:
▪ This product is suitable for use in conditions with heavy load weights and high production efficiency requirements;
▪ It can effectively cover a circular working area, achieve 200° of rotating lifting operations, with a maximum load of 5 tons and an arm length of up to 7 meters;
▪ Manual rotation or electric rotation can be selected.
Column-mounted Jib Crane
Product Introduction:
▪ The column-mounted jib crane (also known as a column-mounted cantilever crane) can complete the most challenging overhead lifting tasks and can handle frequent overhead material handling work;
▪ The column-mounted jib crane provides good working coverage within a circular working area and supports tool balancers, pneumatic balancers, vacuum lifting tools, and hoists.
▪ Currently, the high-bo column-mounted jib cranes supplied domestically are made of steel, with a maximum lifting capacity of 5 tons and an arm length of up to 6 meters, capable of achieving 360° of rotating lifting operations;
▪ It adopts a ground installation method, which does not exert pressure on the building's roof structure, using a prefabricated standard modular design structure that can easily expand with the expansion of the work unit center;
▪ Easy to install and lightweight for relocation.
Product Features:
▪ Special design: Box-type support frame design
▪ This design allows the support frame components to be pre-installed on the cantilever components, effectively reducing the installation space requirements and greatly improving the hoist's lifting height;
▪ Compared to traditional tubular structures, the box-type support frame structure increases the stability of equipment operation, reduces the deflection of the cantilever and the vibration of the load, creating a safer operating environment and reducing the damage rate of workpieces.
▪ Easy to operate
▪ Convenient for operators to accurately position loads, easy and efficient;
▪ The top shaft is equipped with precision tapered roller bearings and roller components for longer service life, ensuring smooth operation;
▪ The triangular support angle plate of the base plate minimizes the deflection of the crane, making it easier to operate when accurately positioning loads.
▪ Easy to install
▪ The independent support frame component is separated from the cantilever during installation, allowing for easy installation;
▪ The embedded bearing component greatly reduces the additional clearance required for installation;
▪ The bolted connection between the support frame component and the jib allows for separate installation work, enabling the jib to be installed very close to the factory roof or top obstacles, minimizing the occupation of top space and increasing the hoist's lifting height;
▪ The hoist trolley running stop bolt can be installed in different positions according to the application;
▪ The top-mounted fully sealed bottom entry collector component can be pre-installed or added later. It provides power to the hoist in a 360° rotating application environment.
▪ Safety: The top positioning pin effectively prevents the support frame component from moving upward unexpectedly.
▪ Full rated load application: For powered hoists, 15% of the crane's rated lifting capacity is considered as the total weight of the hoist, hoist trolley, and hook-down device, and 25% of the crane's rated load is considered as impact load. It can provide customers with jib crane products for full rated load applications.
▪ Manual operation or electric operation can be selected (details explained in "Additional Services")
Product Applications:
▪ This product is suitable for use in conditions with heavy load weights and high production efficiency requirements;
▪ It can effectively cover a circular working area, achieve 360° of rotating lifting operations, with a maximum load of 5 tons and an arm length of up to 6 meters;
▪ Manual operation or electric operation can be selected.
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Manufacturing address：intersection of Caibin West Street and Deren Road in Changchun China-Korea (Changchun) International Cooperation Demonstration Zone
Service Address：No.3 Fumin Street, Lvyuan District, Changchun City
Website：www.兴泰起重.中国
www.crane-china.cc
WeChat service number： xingtaiqizhong
Zip Code：130012
Sales Advisory Phone：400-044-6608/13578886608WeChat Synchronization (Mr. Zhang)
After-sales service telephone：18343082566(Mr. Yu)/400-044-6608
Landline：0431-87096377
Fax：0431-87096377
Copyright：Changchun Xingtai Crane Machinery Co.,Ltd