January 11, 2021

Retrofitting new functions in existing harbor cranes can generate operational and safety gains not included in cranes shipped 15 to 20 years ago, including the Tyber Gantry (RTG) and Rail Mounted Gantry (RMG) types from Ship-to-Shore (STS). Here Dmitry Lapin, Knowledge and Development Manager at Port Services, Konecranes, deals with retrofit options that have proven themselves in international applications.

Sooner or later, owners of cargo handling equipment in ports will be faced with a number of technical and organizational issues for the future. After 15 to 20 years of operation, the steel structure and mechanical components of most port hoists are still working well. However, these cranes are often out of date for several reasons:

  1. Lack of spare parts and technical support for obsolete components. The next generation of electronics and computerized parts will be available every 5-7 years.
  2. Stricter security requirements. The regulations for the safety of personnel, cargo and hoists are stricter compared to regulations from 15 to 20 years ago.
  3. Improvements in ergonomic and operational design. Technological developments have given modern hoisting machines a number of features that make the work of operators easier.
  4. Environmental concerns. Modern companies and their customers want to reduce CO2 emissions (e.g. for cranes with diesel aggregates) and use environmentally friendly materials in the manufacture of their equipment. Old cranes have to be adapted to the current requirements.

In essence, crane owners in ports tell crane manufacturers, “We want our old cranes to have the same systems and functions as new cranes and that this shouldn’t be expensive.” New technology can be added to an existing crane by retrofitting or modernizing it. The main difference between the two methods – retrofitting or modernization – is that the retrofitting has a higher level of standardization, usually between 70 and 95%.

In other words, a retrofit is mostly a ready-made, off-the-shelf product that can be applied to a particular model, brand, or type of crane – sometimes even to all of the cranes in a terminal or company fleet. Installing this product on a given crane requires around 5 to 30% of the engineering work of a modernization. In contrast, a modernization is a unique product that was developed only for one crane. Retrofitting is a mass product. If the retrofit can be applied to multiple cranes in a fleet, it only needs to be designed once. This translates into significant savings, lowers the overall price, and makes it a more competitive option.

The four reasons that make cranes obsolete have spurred the development of the four main types of retrofits:

  1. Retrofitting the drive and control system.
  2. Retrofitting the power supply system.
  3. Retrofits for automation and operator support.
  4. Security-supporting retrofits.

Each of these types of retrofits can be installed separately or in combination with other types of retrofits. For a deeper understanding of the retrofit concept, we consider each type separately.

Image courtesy Konecranes

Retrofitting of drives and control systems

Most of the old crane control systems based on technologies such as contactors, relays, thyristor DC drives and some frequency converter AC drives are technically and physically obsolete. Manufacturers no longer offer spare parts or technical support for obsolete components. Repair work on old electrical and electronic components is quite expensive and sometimes not even possible. All of this results in crane downtime.

Owners with several identical cranes sometimes use one of them as a spare part. However, this cannibalization can only ever be a temporary solution. When they have both old and new cranes in their fleet, the owners quickly realize that the modern diagnostic systems for new cranes help to identify faults faster, which improves the reliability and availability of the cranes. Even so, their old cranes are still in good condition and don’t need to be replaced yet.
The question is: “How is it possible to keep the old crane reliable and improve its functionality on a small budget?” The answer is: “retrofits”. Konecranes has been upgrading harbor cranes since 2013. Over a period of seven years until 2020, the retrofitting of the drive and control system was installed on 154 rubber-tyred portal cranes (RTG) worldwide. The concept and scope of the retrofits were defined in order to maximize the standardization of the modular structure and the specification of the components.

Standard retrofitting of the drive and control system includes:

  • New electrical switchboards (including frequency converters) in the electrical room of the crane
  • New crane management system (CMS)
  • New control panel for the operator to replace the old one
  • Improved PLC components (Programmable Logic Controller) to support Ethernet, Profinet and Profibus protocols
  • Updated PLC software
  • New 3G / 4G modem for remote diagnosis and monitoring functions

Optional extras when retrofitting the drive and control system are:

  • New braking resistors for frequency converters
  • New trolley cable chain (or garland)
  • New operating devices (e.g. converting analog joysticks to digital ones)

Other retrofits such as safety, automation and power supply systems can serve as additional options for retrofitting the drive and control system. The modular structure of these retrofits facilitates integration into the general crane control and diagnostic system.

Konecranes assembles and tests all retrofit components at the company’s facility in southern Finland. All tests are performed prior to shipment to reduce equipment downtime. Depending on the options, retrofitting will keep the crane out of operation for an average of 7 to 10 days during installation and commissioning.

Retrofitting a drive and control system is an efficient and economical solution. At only 15-30% of the price of a new crane (depending on the options), a customer receives a crane with new, modern control and diagnostic systems, remote monitoring functions and extensive spare parts support from Konecranes. It uses high-speed standard data transmission via Ethernet and Profinet and a modular PLC software structure enables smooth integration with other systems. For example, a crane could be connected to the Terminal Operating System (TOS) via Ethernet. In this way, the AGB can exchange data with the crane. This is the first step towards terminal automation.

A single accident can prove disruptive and expensive. Photo courtesy Konecranes

Retrofitting the power supply

As environmental regulations have become more stringent around the world, the demand for power retrofits has increased. Reducing CO2 emissions is the main goal of lower-emission diesel engines, hybrid systems (with batteries or supercapacitors for storage) or full electrification.

The complete electrification of the crane, which is equipped with a diesel-electric power supply, is the most expensive, but also the most environmentally friendly option. The high costs are due to the mechanical and electrical changes to the crane, as well as adjustments to the yard infrastructure, including cabling, new transformers, crane feed, etc.

Cranes have not used hybrid drive systems for a long time, although the automotive industry has been installing them in cars for over 10 years. A diesel-electric device with a lower output is used, which compensates for power consumption peaks with storage energy. While the crane is idling, the generator builds up the energy storage. A hybrid system saves fuel and causes lower emissions compared to conventional diesel-electric electricity.

However, hybrid power must use high capacity energy storage to be efficient. Lithium-ion batteries and supercapacitors are expensive and have a limited lifespan. Sometimes investing in a hybrid system never pays off because the fuel savings are less than the price of the system. To alleviate this problem, some countries (such as the US) are funding retrofits to reduce emissions. Diesel-electric crane owners are very willing to upgrade their equipment to run hybrid or all-electric if the government supports them in making the change.

Retrofitting busbars and cable drums are the two main methods of converting an RTG crane to fully electric operation. Retrofitting the busbar requires many changes to the yard, including an electrified fence on the side of the yard, feed points, and other engineering changes. For this reason, it is recommended for large terminals with many cranes. On the other hand, most of a cable reel retrofit is attached to the side of each crane. Retrofitting the cable drum is recommended for small terminals.

Conclusion

The main advantages of retrofits compared to conventional modernizations are:

  • Modularity – More standardized solutions with less customized design result in cost savings and a lower price for the end customer
  • Integration – The same retrofit concept can be integrated into different crane types and brands
  • Succession – A retrofit opens the way for further retrofits and builds on a long-term investment in automation and reliability


About the author

The Author: Dmitry Lapin is a crane engineer with extensive knowledge of crane design, modernization and maintenance, including 20 years of engineering, thought leadership and training experience within the Konecranes global organization. He graduated from Odesa State Maritime University with a Master of Science (specialist) and a degree in electrical engineering and mechanical engineering (hons) as well as a chair in professor, port cranes and cargo handling at the university. He has extensive experience in developing and managing new crane products, modernizing cranes and solving technical problems, as well as training managerial positions for crane engineers and maintenance personnel. His areas of expertise include crane electrical engineering, automation, machine calculation, product development, commissioning and commissioning of cranes, modernization and maintenance, product development, product management and project management.