When thinking about where your business uses the most energy, it is estimated motor loads consume 60% of electrical energy used in industry. There are many ways to mitigate this, including installing VSDs for general motor loads. Yet, Schneider Electric reminds us that efficient motor management starts with the optimal design of your motor and electrical installation.

Electrical motor management is often associated with motor maintenance but in reality, involves much more. A motor drive system comprises many parts from the supply source, controls, motor and load. Each element also has many considerations that affect both selection and operating performance.

Motor management

Everyone is busy and the five-step approach suggested by Schneider Electric saves on installation costs and avoids production losses during operation. The five steps to consider are:

Analyse the application

Most motor loads in industry are pumps, fans, conveyors, compressors and their operational characteristics in terms of speed and inertia are similar. Although different applications have different torque requirements and inertias that can affect the choice of motor controller. Future requirements of the industrial process may also change.

This can affect the starting, stopping, speed control, and synchronization of the operation with other applications in the same process. Consider them all to be sure of a full understanding of the duty and application, to avoid over-engineering the solution.

Select motor controller

Having understood the application requirements, consider next the best motor control solution. Depending on the application and motor characteristics, the choices for low voltage and medium voltage applications may be different.

Switchgear integrated contactors; circuit-breakers; soft-starters and auto-transformer starters are common choices. If speed synchronization to another process is relevant, or energy savings are important, then a variable speed drive may be appropriate. If not, the focus will be on motor starting technique. Frequent motor starts, large and critical motors, or weak power networks will need a progressive start solution. Although more expensive these will save on the maintenance of your motors and reduce constraints on parallel loads during start. Traditional motor starters offer the lowest integration cost and are suitable for most cases.

Select motor protection

Motor protection relates to faults and overloads and is needed to protect the motor drive system from damage. It can be from overload relays or through a variable speed drive. Try to select the features for the real need as most motors need simple protection like overload and earth or phase fault. For protecting critical motors, consider monitoring of power, frequency, phase failure and, under and overvoltage. Using more advanced protection methods increases initial cost but will reduce unplanned downtime through early warning of problems.

Impact of power quality

Power quality impacts the motor and parallel loads as harmonics and power factors can affect an entire industrial system. They are both related to the motor control solution in use. Importantly, power quality issues are not always immediately apparent and can affect several kinds of equipment. Active or passive harmonic filters will resolve most harmonic issues. Selecting low harmonic drives, especially for larger loads will solve the problem at the source. For power factor improvement, capacitor banks are the best solution.

Managing motor assets

Finally, supervising the motor and load prevents failures from developing and avoids emergency maintenance and production losses. There are various solutions for predictive maintenance such as vibration monitoring, insulation condition monitoring, and motor and load monitoring through current and voltage measurements. It is also advisable to connect these sensors to the supervisory SCADA system. This informs all relevant staff about developing faults and enables the scheduling of maintenance actions. Services-oriented drives like ATV600 and ATV900 series can also perform this monitoring.

These steps represent the best ways to ensure correct motor operation, lower installation costs and reduce the impact on the power network.