Modern electric actuators: retrofitting ensures the future viability of systems

Regardless of the area of application - be it in sewage treatment plants, power plants or tank farms - the time often comes for modernization after many years of use of the operating components. By upgrading with intelligent electric actuators, even older systems can be successfully transferred to the digital era.

There are numerous reasons for modernizing or replacing operating components such as actuators. Is a new control system about to be implemented? Do higher process accuracy requirements need to be met? Do gas pipes need to be modified for the use of hydrogen? In addition to these common questions, other factors are also driving modernization, such as the desire for a higher degree of automation, improved plant performance or the use of digital tools for monitoring and early detection of maintenance requirements. The replacement of obsolete equipment, which is increasingly breaking down, or the discontinuation of production and the supply of spare parts by the manufacturer can also make modernization necessary.

In many cases, it has been shown that the installation of modern, high-performance actuators not only increases the efficiency and safety of processes, but also increases the availability of systems and reduces operating costs.

Seamless integration and extended diagnostic functions

When introducing a new DCS, the communication standard at field level often changes, which, however, does not necessarily require the replacement of complete actuators. With modular actuators, such as the SA multi-turn actuators and the SQ part-turn actuators from AUMA, retrofitting a control system with the appropriate interface may be sufficient, provided the actuator itself still functions properly. This reduces investment costs and allows existing system components to be used for longer. Thanks to compatible interfaces for all common communication systems, from fieldbuses such as Profibus DP and Modbus RTU to Industrial Ethernet protocols such as Profinet, Modbus TCP and Ethernet/IP, these actuators can be seamlessly integrated into modern control systems.

Precise, modern SEVEN Hi-Mod modulating actuators make the Duisburg-Huckingen power plant fit for the future.
Source: AUMA

Furthermore, investing in modern, intelligent actuators offers advantages when the monitoring of field devices is extended or new diagnostic requirements are made that older actuator technologies no longer meet. AUMA actuators with integrated sensors and comprehensive data acquisition lay the foundation for effective digitalization. They automatically collect important operating and device data such as switching frequency, motor running times and temperatures as well as a time-stamped event log. Automated analysis and diagnostic functions, combined with CORALINK, AUMA's digital ecosystem, provide plant operators with insights into the status of their actuators at any time. They receive recommendations for action for each actuator to ensure availability and avoid costly failures. Remote diagnostics via the DCS are also possible.

Efficient retrofitting and automation of fittings

Even today, many valves that are rarely operated are often only equipped with a handwheel for manual operation. Operators cite various reasons for switching to electric actuators, such as a lack of personnel, high personnel costs due to long distances or valve operation that is too slow. The central control or monitoring of valves from the control room also often makes automation necessary. In such retrofit projects, it is crucial that the connection dimensions and required process parameters such as torque and operating time of each valve are precisely recorded at the beginning in order to select the appropriate actuators.

Before the retrofit.
© AUMA

To respond to these challenges, AUMA offers comprehensive retrofit services. Experienced experts within the AUMA service organization work together with plant operators or planners to develop tailor-made modernization concepts for actuator technology. The process begins with a detailed analysis of the existing conditions and requirements in order to always find the most efficient and resource-saving solution. The retrofit experts then take care of all project implementation steps, from precise on-site measurements to the selection and adaptation of suitable actuators from AUMA's extensive range, right through to on-time installation and commissioning by qualified service technicians. These services are not only available in German-speaking countries, but also worldwide via the global AUMA service network. Numerous successfully completed projects in various plants, from power stations to water and waste water treatment plants and tank farms, testify to the benefits of such modernization measures. Two practical examples are described in more detail below. Further information is also available at retrofit.auma.com.

Power plant retrofit with modern variable speed actuators

AUMA Service is updating the Duisburg-Huckingen power plant with modern, precise modulating actuators to make the plant future-proof.

As part of the gradual modernization of the control technology and the associated field devices at the Duisburg-Huckingen power plant, RWE is planning to replace over 100 old control actuators in each of the two power plant units with modern actuators. The existing actuators correspond to operating mode S9 for continuous control in accordance with DIN 60034-1, which is roughly equivalent to class D of the current EN 15714-2 standard for actuators. The new actuators should therefore also meet this classification.

The torque is transmitted from the actuators to the valves via various lever mechanisms, which are to be retained. It is essential for RWE to receive the entire project management from a single source in order to be able to react quickly to any problems. The desired service covers all steps - from data acquisition and actuator design to delivery and installation, commissioning and test runs.

After the retrofit: adapter plates between the new gearboxes and the old brackets have made it possible to retain the complete kinematics on the valves and replace the existing old actuators 1:1 with new, modern SEVEN Hi-Mod modulating actuators.
© AUMA

The solution - precise and customized

In view of the high-precision and very dynamic control tasks that the actuators have to perform, AUMA proposed the high-end SEVEN HiMod modulating actuators. The actuators developed by the AUMA Group company SIPOS Aktorik support continuous control according to class D. The actuators are combined with high-quality AUMA S.1 part-turn gearboxes. The highlight: The gearboxes have been modified so that the gearbox output shaft is identical to the shaft of the old actuators. By using appropriate adapter plates between the new gearbox and the old brackets, it was possible to retain the complete kinematics on the valves and mount the existing levers directly on the gearbox output. This meant that the existing old actuators could be replaced 1:1 with new, modern modulating actuators, which are streets ahead of them in terms of ease of operation, serviceability and functionality. Communication with the control system (4-20 mA setpoint specification and 4-20 mA position feedback) is also retained 1:1. The operator did not have to do any rewiring, all cables are retained.

AUMA Service took over the complete service package, including dismantling the old devices, installing the new devices, commissioning and test running the actuators. A weighty task, as the heaviest of the old actuators weighed 700 kg. The AUMA service experts have the necessary equipment, are appropriately trained and therefore predestined for such tasks.