The importance of motor protection in modern industries
According to Schneider Electric, it is simple to underestimate the importance of electric motor protection in modern industries. Since their development 150 years ago, the design and performance of electric motors have undergone many refinements. But their fundamental function remains unchanged: they convert electrical energy into mechanical movement. Overall, electric motors provide the power to run billions of devices, from electric toothbrushes to giant tunnel boring machines.
Induction motors dominate industrial and manufacturing industries and in these sectors, where they convert raw materials into finished goods. Production and manufacturing companies depend on electric motors for driving conveyors, compressors, agitators, fans and machine control.
Research estimates that motors consume over 50% of all the electrical power used in today’s manufacturing plants. Even considering the increased use of VSDs and higher efficiency motors, the forecast is for this proportion to increase. The use of servo motors is also growing, but motor failure can be expensive as it can cause plant stoppages, damage to equipment, and risk to people or the environment. It is essential to protect motors and starters from electrical damage, providing users with maximum operating time and cut down on any chance of outages. With more complex industrial setups, unprotected motor failures can result in production downtime, losses and breakdowns in the machinery.
Integrated motor protection
The last few decades have seen a significant investment of resources for making operating systems even more efficient. Moreover, control manufacturers like Schneider Electric have chosen to develop improved cost-effective motor protection systems.
Using motor protection and overload relays in circuits to safeguard motors and motor conductors protects the system from damage by prolonged periods of overcurrent circuit conditions. Some of the functions of these relays are:
- Allow harmless, temporary overloads (like in the case of motor starters) without disrupting the circuit.
- Trip and open circuits if the current is high enough to cause motor damage over a period.
- Manually or automatically reset after removal of the overload.
By exposing motors to continuous current and prolonged periods at locked rotor condition, severe damage to the motor and motor circuit conductors might occur. Other conditions that can damage or destroy motors. Specifically:
- High or low supply voltage
- Phase unbalance
- Continuous excessive loading
- Single phasing
- Jam or stall conditions
- Ground/earth faults
- Mechanical failures like seized motor bearing or binding mechanical linkages
Importantly, the development of intelligent motor controllers, relays and integrating automation network communication improves performance. Robust connection and communication between the motor and the automation system play a predominant role in reducing instances of motor failure.
Many companies fail to pursue the strategy of integrating motor control, automation, and energy systems because of the perceived technical complexities. Moreover, systems integrators with knowledge in all three of these domains can help plant operators to combine and optimise these systems, thereby helping to drive profitable production.
Improving motor operation and uptime
Achieving improved motor operation and uptime can be through several approaches used together with the automation system for performance optimisation. Adding new components can also play a role in improving motor reliability, efficiency, and uptime.
As an example, intelligent motor controllers and relays can provide an automatic means for motor starts and stops, forward or reverse rotation, regulation of speed, limitation of torque, and motor protection against overloads and electrical faults.
Intelligent motor control can also provide energy consumption data for each motor, resulting in reduced energy costs so their function can better align to a workload.
Multifunction meters and intelligent breakers check the quality and quantity of electrical energy. Capturing data from these devices can be done through energy monitoring systems such as Schneider Electric’s Power Monitoring Expert (PME).
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