Why choose variable frequency cranes over conventional ones?

Cranes are the vital link between raw materials, production lines and finished goods. As the demand for smart manufacturing and green production increases, the limitations of fixed-frequency cranes become more apparent. However, variable frequency cranes have gained prominence as the preferred choice for many enterprises thanks to the advantages offered by technological advancements. How do variable frequency cranes compare to conventional cranes?

I. Energy efficiency and cost reduction: Long-term operating costs cut by 20%-30%.

A key issue with conventional cranes is their high energy consumption. Fixed-frequency motors operate at a constant speed, maintaining full power output regardless of the load. This wastes electricity and increases grid load due to current surges.

In contrast, variable frequency cranes utilise variable frequency speed control technology to dynamically adjust motor speed based on actual load requirements. When lifting light loads or moving with an empty hook, for example, the motor automatically reduces speed to minimise energy consumption. During full-load operation, meanwhile, smooth speed regulation prevents sudden power surges.

Take the variable-frequency gantry crane customised by Henan Mine Crane for Baosteel Group, for example. Its permanent magnet synchronous variable-frequency motor reduces energy consumption by 20%-30% compared to the asynchronous motors used in conventional fixed-frequency cranes.

Additionally, the VFD crane employs a soft-start mode during operation, with a starting current of only one-third that of conventional cranes. This prevents impact on the workshop power grid and reduces equipment shutdowns caused by voltage fluctuations.

II. Precision control: Minimising Sway and Impact to Enhance Operational Efficiency and Material Safety

Conventional cranes, which are limited by fixed-speed motors, often experience sudden braking and acceleration.

In contrast, variable-frequency cranes achieve smooth speed regulation and precise positioning through coordinated control of the PLC and VFD.

Motor speed can be increased gradually from 0 to the rated speed, with gradual deceleration during stops. Load sway is kept to within 5 cm, making these cranes particularly suitable for use in steel mills, where they can transport high-temperature steel billets and large-tonnage plates.

Positioning accuracy: The variable-frequency system precisely controls the travel speed and start/stop positions of both the main and auxiliary hoists, achieving positioning accuracy of ±5 mm. During container handling by port gantry cranes, precise alignment is achieved without the need for repeated adjustments, boosting operational efficiency by over 30%.

III. Extended Equipment Lifespan: Reduced component wear and lower maintenance costs:

Conventional cranes subject core components to continuous impact during starts and stops, resulting in premature wear of motor bearings due to current surges.

Variable frequency cranes minimise component damage through two key design features:

Soft start/stop minimises mechanical impact: Current surges are eliminated during startup, reducing motor and bearing wear rates by 40%. Hard mechanical braking is also eliminated during stops, extending brake pad lifespan to 12–18 months between replacements and reducing maintenance frequency.

In summary, variable frequency cranes are a wise choice for short-term investment and long-term returns.

Although variable frequency cranes have slightly higher initial procurement costs compared to conventional cranes, they are a wise choice for short-term investment and long-term returns. However, from a long-term operational perspective, they are particularly well-suited to scenarios requiring high-frequency, high-safety operations, such as in the metallurgy, port and heavy machinery industries.

As a leading global crane supplier, Henan Mine Crane offers a comprehensive range of products from 5 to 500 tons. We provide customised designs based on client site drawings, load characteristics and environmental parameters. Our full lifecycle services deliver one-stop solutions, including site surveys, design planning, installation, commissioning and regular maintenance.