Motors are the core of many applications. Motor protection is thus crucial in making sure a machine, system and its associated production processes run reliably and smoothly. However, today, motor protection components are capable of much more.

Devan Reddy, product manager at Eaton (Wadeville) explains how providing detailed information about the status of a motor can make an important contribution to improving system availability.

Electricity producers in sub-Saharan Africa face an enormous challenge in getting the continent’s 950 million inhabitants connected to stable, quality power with over 600 million having no access at all and most countries struggling with electricity rates of around 20%.

Those who are fortunate enough to be connected deal with persistent outages due to poor maintenance schedules and regular system malfunctions due to a lack of adequate monitoring and protection infrastructure.

Most power stations on the continent employing motorised thermal plants, which heat water and generate the steam that spins the turbines driving electrical generators. The security and service life of these motors depend greatly on how they are protected.

The need for protection devices to ensure that motors, associated machines and systems are protected from damage, and to keep people involved in operating equipment safe from injuries relating to blocked start-ups, overloads, short circuits or external conductor failures in three-phase power supplies can’t be overstated.

In addition to protection, users increasingly want added functions. For example, knowing the current load status is vital and enables users to take early preventive measures when the motor load increases quickly – before the circuit breaker suddenly trips and the system comes to a standstill.

Detailed diagnostic information about the motor circuit breaker tripping can also help in the troubleshooting process. Being able to monitor the power consumption of individual motors and document any changes is extremely practical in this age of efficiency.

Implementing all of this requires intelligent motor protection systems capable of recording and transmitting any relevant data. In contemporary motor protection systems, we generally see two main technologies: the classic electromechanical circuit breaker with adjustable rated current, which trip in the event of a short circuit; and electronic motor monitoring systems, which use Profibus or Modbus field bus systems to transmit the recorded data to higher-level controls.

The latter are complex motor management systems that are much more expensive than an electromechanical motor protection switch. They require more installation space and generally provide unnecessary functions. Fieldbus systems are also still relatively rare, even though there is great interest in the potential of enhanced, preventive motor protection systems.

A look at motor current and overload

An alternative solution is the PKE motor protection circuit breaker which features electronic wide-range overload protection. The system fulfils the many functions required of a compact state-of-the-art motor protection device.

Alongside its basic protection function, the system records relevant information to provide a comprehensive evaluation of the motor’s status. The design is similar to that of a traditional electromechanical motor protection switch, making it easy to install without having any negative influence on the development of a project.

Thanks to its integrated electronic release unit, the PKE is capable of recording relevant information, including motor current, overload and other diagnostic data, before feeding it to the end application for further processing.

The PKE electronic motor protection circuit breaker offers enhanced motor protection with optimum price-performance relative to more complex motor management systems.

In motors with stable current requirements, any fluctuation in the current is easy to record. Increasing readings could indicate wear and can help in scheduling maintenance work. For instance, a reduction in current to a pump would indicate it was running dry.

The ability to record overloads as analogue quantities are critical to operating safety. The figures help operators assess and analyse load in a motor, and, in the event of an impending shut-down, 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 also be improved to prevent unintentional tripping of the motor protection system. In such a scenario, the PKE plays a significant role in ensuring safe operation and increased availability.

Easier troubleshooting, IE3-compatible

If tripped, the PKE electronic motor protection circuit breaker gives detailed information about the cause of the fault as well as providing protection. Here, traditional 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.

The plug-in electronic trip block comes with just five types, meaning the PKE – which is available as a stand-alone motor protection switch or as a complete motor starter combination for up to 15kW – requires a motor current range from 0.3 to 65 A.

By comparison, an electronic motor protection switch also supplies information about the possible phase failure that caused the shutdown. Transmitted values also include the overload setting and the CLASS settings (5-20), which are provided by the PKE. The figures make checking the parameterisation of the device easier and enable the operator to detect any incorrect settings or unreliable changes during operations. Any early tripping or overloading of the connected motor can, therefore, be prevented.

Eaton’s PKE electronic motor protection circuit breaker in combination with the company’s SmartWire-DT provides powerful and efficient motor protection to increase operating safety and improve machine or system availability. It also helps optimise maintenance schedules and, in the event of a fault, can reduce repair times thanks to its provision of enhanced diagnostic data.

As an added benefit, the design and operation are the same as a PKZ electromechanical circuit breaker, making it even easier to use. The PKE’s intelligent motor protection allow machine and system builders to create simpler, more cost-effective and compact solutions; making systems even more reliable.

SmartWire-DT, Eaton’s intelligent connection system, connects simple components such as control, signalling and switching equipment; using communication modules connected directly to the components. This replaces complicated control wiring and eliminates the need for the decentralised I/O level.

About Eaton

Eaton is a power management company with 2017 sales of $20.4 billion. We provide energy-efficient solutions that help our customers effectively manage electrical, hydraulic and mechanical power more efficiently, safely and sustainably. Eaton is dedicated to improving the quality of life and the environment through the use of power management technologies and services. Eaton has approximately 96,000 employees and sells products to customers in more than 175 countries.

About Eaton in Africa

Eaton has been in Africa since 1927 with offices in South Africa, Kenya, Ivory Coast, Morocco and Nigeria, with 200k ft² of manufacturing space located in South Africa and Morocco. A certified BBBEE Level 1 contributor in South Africa, Eaton offers a broad portfolio supplemented by “made for Africa” products and solutions. Eaton has over 700 employees and numerous distributors across the region, allowing us the opportunity to help our customers grow and provide sustainable economic benefits to the communities in which we operate. For more information visit