Consistent crane control

CONSISTENT CRANE CONTROL

Crane control using cressall motor control resistors

UNLOCKING EFFICIENT MOTOR CONTROL WITH RESISTORS

Cranes are the backbone of industries like construction, manufacturing and logistics, where the lifting and precise placement of heavy loads are essential. Ensuring that cranes operate smoothly, safely and efficiently requires sophisticated motor control systems. Here, Mike Torbitt, managing director of Cressall Resistors, explains the role that resistors can play in ensuring consistent, efficient crane control.

From erecting skyscrapers and loading cargo at ports to maintaining power plants and assembling aircraft, cranes are crucial for operations that require robust and reliable lifting solutions. As the construction industry continues building upwards — with 600 more skyscrapers in the pipeline for London alone — cranes will be key to realising future industry projects.

A CRUCIAL CONTROL SYSTEM

At the heart of crane operations is a control system, which is responsible for managing the various movements and functions of the crane. These systems include both mechanical controls, like gears and pulleys, and electrical controls, such as motor drives and braking systems. The primary objective of a crane control system is to ensure that the crane operates efficiently and safely — whether that’s lifting a beam into place on a skyscraper or positioning a delicate component in a manufacturing process.

Motor control systems in cranes play a crucial role in managing the speed, torque and direction of the crane’s movements. They enable operators to have precise control over the crane’s actions, from the gentle lifting of a load to the exact positioning of materials.

Advanced control systems also include features for monitoring and adjusting performance in real-time, which helps to maintain the operational efficiency and safety of the crane. By integrating these controls, cranes can achieve higher productivity, reduced operational costs and improved safety.

THE ROLE OF MOTORS

Motors are the powerhouses behind the various functions of a crane, driving the mechanisms that lift, lower and move loads. In crane systems, motors are used to control different parts, including the hoist, trolley and the crane’s overall movement on its tracks or rails. Each motor’s performance must be precisely managed to ensure that the crane can handle heavy loads safely and efficiently. Several advanced motor control technologies are required to provide the necessary regulation and coordination for optimal crane operation.

Variable frequency drives (VFDs) are one critical component in crane motor control systems. They adjust the frequency of the electrical power supplied to the motors, allowing for precise control of motor speed and torque. This is essential for the smooth lifting and lowering of loads, as well as for finetuning the crane’s movements. By optimising motor performance, VFDs help reduce energy consumption and mechanical stress, extending the life of the crane’s components and enhancing overall efficiency.

Dynamic braking systems are another essential, allowing for rapid deceleration and stopping of the crane’s movements. This capability is critical for ensuring safety and preventing accidents, especially in emergency situations where quick response times are necessary. Dynamic braking systems help manage the kinetic energy generated by the crane’s movements, converting it into heat and dissipating it safely, which prevents potential hazards associated with uncontrolled load movement.

RESISTOR RELIABILITY

Resistors play a vital role in a crane’s dynamic braking system, by managing power dissipation and ensuring safe and efficient operations. In crane applications, resistors are used in various ways to enhance the performance and reliability of the control systems.

When a crane slows down or stops, the kinetic energy from the moving parts is converted into electrical energy, which needs to be dissipated to prevent damage or overheating. Resistors absorb this energy and convert it into heat, allowing for controlled and safe deceleration. This is crucial for maintaining the stability and safety of the crane, especially when handling heavy loads or during emergency stops.

Cressall Resistors is a leader in power resistor solutions, offers a range of products specifically designed for crane motor control systems. Its dynamic braking resistors are designed specifically for high-power applications, to operate efficiently in demanding and harsh environments often encountered in crane operations.

Motor control systems are the backbone of efficient, safe crane operations. By integrating these technologies, and the resistors that safeguard the systems, cranes can achieve superior performance, reliability and safety, elevating efficiency across many industries.

CRESSALL MOTOR CONTROL RESISTORS

CRESSALL DYNAMIC BRAKING RESISTORS

Power Control Chopper

POWER PROVE LAUNCHES POWER CONTROL CHOPPER FOR CRITICAL TESTING

In response to growing demand for more precise power dissipation, load bank manufacturer Power Prove has launched a dedicated IGBT-based electronic power control chopper, for continuous regulation of its load bank product offering. The power control chopper can be easily integrated into load banks to achieve high power dissipation and a degree of precision superior to that offered by any competitor.

Power Prove, the load bank division Cressall Resistors, commissioned the design of the power control chopper to Italian Internet of Things (IoT) solution developer Techmakers. The combination of Power Prove’s in-depth knowledge of load banks and Techmakers’ expertise in electronic and software-controlled devices has resulted in a powerful, yet cost-effective, solution that meets the growing demands of the market.

A power control chopper is an electrically controlled solid state switch that is used to control the amount of current permitted to flow through a circuit. Normally, a high-power variable load requires multiple fixed value load sections ranging in values for power dissipation with contactors and a logic controller. However, by integrating the power control chopper into the system, a near-infinite set of values for power dissipation can be achieved using just a single resistor.

Power Prove’s chopper also has a closed-loop regulation circuit, which is capable of adapting to fluctuations in voltage and cold resistance variation without any input. Multiple units can be combined to reach high-power dissipation, enabling the load bank to withstand even the greatest of power values with high precision.

Anywhere that requires constant power, whether that’s a healthcare facility, manufacturing plant, or IT data centre, simply cannot afford a complete loss of power. These layers of infrastructure are often secured by an uninterruptible power supply (UPS) that provides power for critical operations if supply from the grid fails.

“The challenge for the managers these systems, which are often deployed as sources of back-up power in a black-out situation is how to determine whether the system is operational and will not fail on the relatively infrequent occasions when their use is required at a critical moment. Regular testing of emergency systems using load banks is therefore essential,” explained Andrew Keith, division director of Power Prove.

“Since these systems provide such a critical safety mechanism, a high level of precision is vital,” continued Keith. “The new power control chopper allows us to provide our load bank customers with a customisable load bank that can be easily integrated into an existing system to provide infinite levels of power adjustment at a degree of precision that is simply not available elsewhere on the market.”

An example of the power control chopper’s application is with battery discharge testing. The chopper can be used with a current feedback loop to provide a genuine constant current load on battery systems up to 1000 V DC. Multiple chopper units can be fitted inside the same load bank, or a combination of traditional fixed loads and chopper modules can be used to create a load bank with the current discharge capacity to suit its application.

In addition, the increasing adoption of electrical vehicles powered by batteries and fuel cells is generating a wide range of operating scenarios that need to be simulated. The development of the power electronic control module allows Power Prove to produce load banks that simulate a much more diverse range of operating conditions for research and development (R&D) testing, system commissioning tests and regular planned maintenance load testing.

The power control chopper is available globally from Power Prove, for more information, visit the website.

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