FEATURE DRIVES, CONTROLS & MOTORS
MOTOR PROTECTION with added functionality
Providing detailed information about the status of a motor protection components make an important contribution to improving system availability, says Herbert Einwag of Eaton
M
otor protection is crucial in making sure a machine, system and associated production processes run reliably and smoothly. The security and service life of a motor depends greatly on how it, along with associated machines and systems, are protected from damage and operators are safe from injury relating to blocked start-ups, overloads, short circuits or external conductor failures in three-phase power supplies. In addition, users increasingly want more
functionality. For instance, knowing the current load status can enable users to take early preventive measures when the motor load is increasing rapidly before the circuit breaker suddenly trips and the system comes to a standstill. Detailed diagnostic information about the motor circuit breaker tripping can help in the troubleshooting process. Being able to monitor power consumption of individual motors and document changes is therefore extremely practical. Implementing all of this requires
intelligent motor protection systems capable of recording and transmitting relevant data. We generally see two main technologies: the classic electromechanical circuit breaker with adjustable rated current which trips in the event of a short circuit; and electronic motor monitoring systems which use Profibus or Modbus systems to transmit the recorded data to higher-level controls. Complex motor management systems are much more expensive than an electromechanical motor protection switch, requiring more installation space. Fieldbus systems are still relatively rare at the device level even though there is great interest in the potential of enhanced, preventive motor protection systems.
MOTOR CURRENT AND OVERLOAD Eaton’s PKE motor protective circuit breaker features electronic wide-range overload protection. Alongside its basic protection function the system records relevant information to provide a comprehensive evaluation of the motor’s status. Similar in design to a traditional electromechanical motor protection switch, it is easy to install without having a negative influence on the development
20 SPRING 2017 | IRISH MANUFACTURING
motor protection switches merely provide information as to whether the trip resulted from an overload or a short circuit and reports an error message to the PLC via the respective control wiring. By comparison an electronic motor
of a project. Thanks to its integrated electronic release unit the PKE can record diagnostic data including motor current overload before feeding it to the end application for further processing. In motors with stable current requirements any fluctuation in the current is easy to record. Increasing readings could indicate wear and a reduction in current to a pump could indicate it was running dry. All this data can be used for predictive
maintenance. The ability to record overloads as analogue quantities is critical to operating safety. The figures help operators assess and analyse load in a motor and in the event of an impending shutdown can enable personnel to take appropriate measures to prevent the circuit breaker from tripping to avoid drive failure. Under differing climatic conditions the monitoring of the load status in a drive feeding a conveyor belt could be improved to prevent unintentional tripping of the motor protection system. The PKE plays a significant role in ensuring safe operation and increased availability.
EASIER TROUBLESHOOTING If tripped the PKE electronic motor protective circuit breaker gives detailed information about the cause of the fault while providing protection. Traditional
SmartWire-DT uses communication modules directly connected to simple components such as control, signalling and switching equipment
protection switch supplies information about the possible phase failure that caused the shutdown. Transmitted values include the overload setting and CLASS settings (5-20) provided by the PKE. The figures simplify checking of the device parameterisation and enable the operator to detect incorrect settings or unreliable changes during operations. Any early tripping or overloading of the connected motor can thus be prevented. When it comes to selecting motor protection elements in accordance with ErP (Energy-related Products) guidelines PKE circuit breakers are suitable for the protection of motors up to energy efficiency class IE3. Switching equipment needs to be checked to ensure it is suitable for IE3 motors as these are subject to far greater feed currents. Eaton has optimised its PKE and PKZ
motor protection devices to comply with the amended requirements. Both have been proved to reliably and safely protect IE2 and IE3 motors.
INTEGRATED INTELLIGENTLY AND FLEXIBLY The PKE motor protective circuit breaker can become a communication-capable switching device in an instant thanks to Eaton’s SmartWire-DT intelligent wiring and communication technology. It makes planning, projecting, wiring, testing and commissioning electrical systems faster than conventional wiring. Intelligent wiring makes it easier to
switch between connections for control and signalling equipment, auxiliary switches, signal lights, motor protection switches, soft starters, frequency converters and circuits and can simultaneously convert them into communication-capable automation components. The data recorded by the switching equipment can be transmitted to conventional industrial fieldbuses.
Eaton
www.eaton.eu
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