Electricity and Control April 2024

MEASUREMENT + INSTRUMENTATION

Monitoring power quality to minimise energy waste

Saving energy and minimising waste are critical aspects of energy use. In all industries, looking for energy savings means monitoring power consumption rates and developing an energy-saving power quality management plan. Here, Fluke outlines the steps to take.

Benchmarking electrical energy consumption The first step in developing a power quality management programme is benchmarking the current electrical ener gy consumption across the facility. From that initial survey, business owners or energy managers can look for quick and easy solutions to start minimising energy waste: for instance, areas that are typically closed on the weekends and can be shut down. Areas that contribute to energy us age outside significant assets should be monitored, sup plementary electrical heating, lighting being left on, or com puters similarly being left on when not in use. Once those quick wins have been identified and action taken, more detailed studies should be conducted through out the building or facility. The Fluke 1777 three-phase power quality analyser can be used to run load studies on assets across the facility. These measurements will indicate where significant energy savings could be made by switching off some systems during the night or non-operating times. Advanced power quality considerations The next step in reducing energy consumption is to look at where energy waste arises. One area to focus on is losses in conductors. As current flows through conductors, some energy generated will inevitably be wasted as heat. Fig uring out how to level this issue returns to the fundamen tal I2R equation indicating the power delivered. And this leaves two possible solutions: reduce the current flow (I) to

lower kilowatts or reduce the resistance (R). Although both present a problem: - Lowering current (I) means the load will not operate correctly - Reducing resistance (R) can cost more because it requires the installation of copper or aluminium con ductors. What is the best solution? Consider the conductor sizing. The National Electric Code (NFPA 70 or NEC 100) provides guidance on determining the correct size of a conductor for the respective applica tion, describing the ideal conductor size for almost any cir cumstance. The primary consideration for conductor sizing is ensuring the safe operation of the conductors with the most appropriate insulation. This depends on the length, cross-sectional area, and anticipated current rating required. This approach can provide minimised energy losses, typi cally 2% or less, and an acceptable voltage drop in the con ductor. Additional possibilities could include installing higher efficiency loads and checking if motors are correctly sized – or possibly oversized for the respective application. Wasted power The codes and guidelines are great when installing new equipment, but implementation does not always work out ideally once the cabling installation is completed and the loads are installed. Furthermore, over time, the equipment may change with additions or adjustments; moves and age can significantly affect energy waste. Key areas where en ergy waste may occur are related to power quality: voltage regulation, harmonics, power factor and unbalanced loads. Voltage regulation Voltage regulation works to reduce energy consumption in voltage-dependent loads. It reduces or controls the voltage levels within the equipment manufacturer’s specifications to deliver energy savings. As more efficient loads are installed at a transformer, the voltage in the system may rise or may be incorrectly controlled. The Fluke 1777 power quality analyser can be used to catch voltage regulation issues, checking for transient volt ages or voltage imbalance. Both issues can lead to failure, unplanned downtime, and expensive repairs.

Harmonics Harmonics distort voltage and current so that the ideal sine

Using power quality analysers, energy managers can locate energy waste and act to gain energy savings.

18 Electricity + Control APRIL 2024