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More than Saving Energy – Potential Opportunities to be realised by upgrading your equipment

Legacy equipment performing day to day tasks are the backbone of the infrastructure and services that we rely on when we work, shop, cook, rest and play. Many of these systems have been in use for years, many of which having been designed to use state of the art technologies available at the time, which is now some years ago. Product advances during the interim have improved process efficiency, introduced functionality and feedback that can be exploited by upgrading the system today.

The Advent of Electronic Commutation in Motor Technology

One of the advances in technology has been the introduction and widespread use of Electronically Commutated motor technology.

Traditional AC induction motors commonly used in legacy equipment rely on inducing a magnetic field and current flow from the stator into the rotor to create movement. This process involves several losses in transferring the energy from the stator to the rotor including induction loss (mass losses in the laminations), air gap loss, winding losses, rotor resistance loss.

In contrast, a permanent magnet DC motor uses a simple stator winding to excite a magnetic field which attracts/repels permanent magnets in the rotor dependant on the direction of current flow through the winding. Using a permanent magnet instead of the process of induction eliminates some of the work required to create rotation.

The induction loss (mass losses in the laminations), air gap loss and rotor resistance loss of an AC induction motor do not apply to a permanent magnet motor. This means that less energy is required to produce the same output and the whole motor system runs cooler as less energy is lost through inefficiencies converting electrical into rotational energy.

 

Benefits of upgrading from AC induction to EC permanent magnet Motor Technology

Speed Control

AC Motor Speed Control

To change the speed of the motor an external device would be required either to reduce the voltage to the windings (transformer, Variac or Triac voltage reduction) or by changing the frequency (Inverter drives).

               AC Voltage control                                   Frequency Inverter Control

Use of these speed control devices causes weak field conditions, introducing slip losses which slow the motor. The slip losses are energy losses which are dissipated as heat causing the motor to run hot, reducing the life expectancy of the grease in the bearings and shortening the life of the fan.

EC Motor Speed Control

More recently, Electronically Commutated motors have been designed which incorporate speed control on-board. The speed of an EC motor is controlled by the voltage applied to the windings, the voltage applied to the windings is controlled by the internal PCB and works in a similar manner to that of a frequency inverter. The main operational difference is that an EC motor will maintain a high level of efficiency down at part load operation.

Power consumption benefit of speed control:

A fixed speed fan will always consume 100% power when switched on.

Using an Electronically Commutated permanent magnet motor with onboard variable speed control, reducing the rotational speed by 20% will reduce the power consumption of the motor by 50%. If the fan speed can be reduced by half, it will be drawing 1/8th (12.5%) of the power it would consume at full speed.

This benefit can be realised if the demand for forced cooling from a fan is seasonal. During the summer months, a fan may often be required to deliver a high-volume flow. However, for most of the rest of the year, lower temperatures will allow lower speed operation and enable energy savings.

Noise benefit of speed control:

Reducing the speed of the fan will also reduce its noise level. Reducing the speed by 20% will result in reducing the noise level by approximately 5dB. If the speed can be reduced by half, the noise level will be 15dB lower than the fan running at full speed.

This benefit can be realised should the demand for cooling fall during the day. During the evening, overnight and in the morning, ambient temperatures and operational demand may fall, allowing the fan to be slowed down. This benefit can help if the environment the equipment is operating in is residential and sensitive to noise.

Life expectancy benefit from speed control:

Running at full speed, a fan will draw the highest power and have the greatest power dissipation, which means the motor will be running at its hottest. This primarily affects the grease in the bearing system, which is the component with the shortest life expectancy.

Running the fan at a reduced speed will create less heat, which will extend the life of the bearings and the longevity of the fan. A longer lasting fan means a greater interval between servicing, saving on the cost of a replacement fan and the labour required to replace it.

Additional Benefits of Upgrading

Big Data

Smart technology requires Smart thinking.

To ensure that you are making the best use of the energy you are consuming, it needs to be measured. The data that is produced requires analysis and meaning attached to it. Once analysed, reasoning can be applied, and decisions can be made on how to reduce losses and maximise efficiency. Upgrading the equipment provides an opportunity to introduce smart technology.

Communication

Being able to communicate with fans, sensors, actuators and other building components allows flexibility, tailoring the operation of the building cooling, ventilation, access and IT systems according to current needs.

Open Protocol

Using a communication language that is free to use, recognised by many industries and has been in use for many years is supported by most manufacturers in the controls industries. These days, products that gather and transport information in management systems are data agnostic – meaning that most devices can translate one form of communication protocol into another as standard. ebm-papst has chosen Modbus as a communication protocol to send and receive data, optimising the use of our products.

Condition Monitoring

Enabling variable speed fans with Modbus communication protocol over an RS485 RTU network can compare the fan set-point with the actual performance data, can trigger alarm outputs and/or emergency operation modes based on if the fan has failed or is wearing out.

Data Hub

In the latest versions of ebm-papst EC motors (Generation-3), external peripheral devices can be controlled, and sensors interrogated by the control management system using datapoints available via the on-board Modbus registers. This latest development can cut down installation time and reduce the complexity of control system wiring.

Summary – Upgrading your equipment is more than an Energy Saving opportunity

Upgrading your equipment, control system or building energy management system can reduce energy consumption by increasing efficiency through the reduction of waste. This not only has monetary benefits but also reduces the operational carbon footprint.

Using Smart technology adds a further dimension to an upgrade, gathering data which through analysis can be used to predict operational requirements and forecast maintenance requirements. Condition monitoring can provide up to the minute oversight of operations and indication of when products or processes are deviating beyond acceptable tolerances.

Smarter also means that the whole system can be rationalised, providing simpler networks with fewer connections that are more economical to implement.

All newly developed ebm-papst products must be technologically and economically superior to its predecessor. This is at the heart of the ebm-papst Greentech philosophy. With the addition of digital intelligent concepts, this has now developed into "GreenIntelligence".

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My background is in Mechanical & Production Engineering however working for ebm-papst that has expanded into electro-mechanical, some electronic and acoustic engineering. When it comes to acquiring and passing on knowledge, I try to keep it as simple and as least painful as possible. I am happy to receive feedback and if there are any questions that arise from anything that gets published. If I don't know the answer to your question immediately, I am sure that I know someone that can help.

5 Mar 2019, 13:36