In this article, Stuart Greenwood of Eaton's Electrical Sector reviews the latest developments and how motor protection switch technologies, through electronics and automation technology, provide efficient and cost-effective systems.
Key factors in motor protection:
The main functions of motor protection circuit breakers include switching, protecting, and disconnecting the main current circuits for motor loads. They simultaneously protect motors from overloads and ensure safe disconnection in the event of a short circuit. They are also suitable for switching motor loads with a low switching frequency, as well as for safely disconnecting the system from the network, for example, for maintenance or repair work.
While past development focused primarily on mechanical properties, such as the motor protection switch, current development is increasingly focused on the field of electronics and automation, particularly regarding communication and fieldbus technology.
Electronic Vision:
Motor protection switches with a wide range of electronic overload protection offer several key advantages compared to bimetallic devices. These include large adjustment ranges, low heat dissipation, multiple trip classes (5, 10, 15, 20), precise tripping characteristics, exceptional long-term stability, and the ability to read parameter data.
The Eaton PKE motor protection circuit breaker, with its wide range of electronic overload protection, measures the current increase through the transformer integrated into the trip unit and evaluates it using a special electronic circuit. In the event of an overload, this circuit sends a pulse through an actuation system to the switching mechanism. PKE motor protection circuit breakers operate at a higher current transfer rate and offer a wider current adjustment range, with a ratio of 1:4, compared to conventional bimetallic motor protection circuit breakers, which have a ratio of 1:1.6.
The wide current adjustment ranges reduce the number of variants by up to 75% compared to those with bimetallic trip units. This minimizes engineering design requirements and costs, while also reducing inventory maintenance and capital investment.
Energy costs are increasingly important when considering the lifecycle costs of industrial installations. PKE electronic motor protection circuit breakers, with their wide electronic overload protection range, have very low heat dissipation (up to 85% less than a bimetallic solution), thus reducing energy consumption and costs. The temperature rise in the switchgear cabinet is also reduced, and cabinet ventilation is often unnecessary.
Optimal information function thanks to SmartWire-DT
In addition to the purely basic on/off functions under normal operating conditions and the basic functions of the motor protection switch, it is now also necessary to obtain additional information to enable operation as efficient as possible.
Whereas previously it was only possible to evaluate switching states or differentiate between overload and short-circuit trip indications, motor circuit breakers with electronic overload protection offer considerably more indication functions, such as diagnostics, status and overload messages, and even current flow. These extensive diagnostic functions accelerate troubleshooting and represent an important quality element. Data transparency increases operational efficiency and reliability of the units in the motor circuit breaker area.
The data transmission platform provided by the innovative SmartWire-DT wiring and communication system offers mature technology for industrial switching networks. With SmartWire-DT, users have a convenient, efficient, and above all, cost-effective system without the need for control wiring and laborious routing through DIP switches. A communication cable is used instead of a single-core control cable. Data from the networked motor starters is transferred directly to the controller and made available to the entire motor protection circuit breaker integrated into SmartWire-DT, adding extra availability, efficiency, and cost-effectiveness to its basic connection/disconnection for normal operation and protection functions. This enables predictive maintenance and repair, increasing system reliability and availability, as well as proactive access for processing data within the motor protection circuit breaker's operating range.
The SmartWire-DT-based control wiring system is one of the core technologies underpinning automation. Adopting control wiring greatly improves the transparency of the automation system. Since the fieldbus and communication bus support information exchange, incorporating control wiring systems essentially means that any information about any aspect
of operation and status
The automation system can be available whenever needed.
The value created by combining motor circuit breaker technology with electronics and automation technology, in terms of functionality, efficiency, and communications, provides the user with a platform for the safe use of motor circuit breakers in switching applications. These integrated technologies are setting benchmarks in the market for electronic motor circuit breakers, which, with all their benefits, have proven essential for cost savings and quality improvement.
Eaton's electrical sector is a global leader with expertise in power distribution and system protection, industrial control and automation, lighting and security systems, support systems and enclosures, solutions for explosion-risk environments, and engineering services. Through its global solutions, Eaton is positioned to address today's most critical challenges in electrical power management.
Eaton is an energy management company that provides energy efficiency solutions to help our customers effectively manage electrical, hydraulic, and mechanical power. A global technology leader, Eaton acquired Cooper Industries plc in 2012. The combined revenues of both companies in 2012 were approximately $21.8 billion. Eaton employs approximately 102,000 people and sells products to customers in more than 175 countries. For more information, please visit www.eaton.eu.
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Article provided by Eaton
