SAVING energy and minimising energy waste are two of the most critical aspects of energy use. In every industry, looking for energy savings means looking at power consumption rates and developing a power quality management energy-saving plan.
The first step in developing a power quality management program is benchmarking current electrical energy consumption across the facility. Through the initial survey, quick and easy solutions, like areas that are typically closed on the weekends and can be shut down, can be found. Areas that contribute to energy usage outside significant assets, like supplementary electrical heating, lighting being left on, and computers not being switched off, should be tracked.
Once ‘quick wins’ have been identified and implemented, more detailed studies throughout the building or campus should be conducted. These include load studies on assets throughout the area, which can be done using the Fluke 1777 Three-Phase Power Quality Analyser. These measurements can show where significant energy-saving can be gained by switching some systems off during the night on non-operating times.
Advanced power quality considerations
As current flows, some generated energy will inevitably become wasted as heat. 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 turn into wasted energy as heat.
Figuring out how to level this issue returns to the fundamental I2R equation indicating the power delivered. But this leaves two possible solutions: reduce the current flow (I) so there is less kW or reduce the resistance (R). Both solutions result in a problem: Lowering the current (I) will cause the load to not operate correctly. Reducing the resistance (R) can cost more because it requires the installation of copper or aluminium conductors. So, what is the best solution?
Consider the conductor sizing. Following the National Electric Code (NFPA 70 or NEC 100) gives useful guidance toward the size of a conductor, describing the ideal conductor size for almost any circumstance. 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 can provide minimised energy losses, typically 2% or less, and an acceptable voltage drop in the conductor. Some additional possibilities would be installing higher efficiency loads and considering checking to see if motors might be oversized for the current application.
Wasted power
These codes and guidelines are great when putting in new work, but it doesn’t always work out ideally once the cabling installation is completed and the loads are installed. Over time, the equipment may change with additions or adjustments; moves and age can significantly affect waste energy. Key areas where energy 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 return energy savings. As more efficient loads are installed at a transformer, the voltage in the system may rise or be incorrectly controlled.
A Fluke 1777 Power Quality Analyser can be used to look for transient voltages and voltage imbalance issues. Both issues can lead to failure, unplanned downtime, and expensive repairs.
Harmonics
Harmonics distort the voltage and current so that the ideal sine wave for voltage is not maintained. One of the most recognised effects of harmonics in electrical systems is the excess heat they create in the conductors carrying them. This results in overheating in phase and neutral conductors, known as “triplen harmonics.”
Unbalanced load
The additional heat from an unbalanced load causes cable runs, motor windings, and transformer issues.
In both these instances, overheating can cause significant damage or complete failure, either of which could lead to unplanned downtime and expensive repairs. To measure and diagnose harmonics, a Fluke 1770 Series Three-Phase Power Quality Analyser can be used.
Once power quality studies reveal areas where energy is being wasted, steps can be taken to fix the issueslance. This may mean setting up a repair or replacement schedule for large motors with mechanical unbalance issues.
