Finding energy waste with Power Quality Management

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Benchmarking electrical energy consumption

The first step in developing a power quality management program is benchmarking
your current electrical energy consumption across the facility. Through that initial survey, you can look for quick and easy solutions to start with, like areas that are typically closed on the weekends and can be shut down. Track areas that contribute to your energy usage outside significant assets, like supplementary electrical heating, lighting being left on, and computers not being switched off.

Once you’ve identified and implemented those quick wins, continue with more detailed studies throughout the building or campus. Run load studies on assets throughout the area using the Fluke 1777 Three-Phase Power Quality Analyser. These measurements can show where you could see significant energy-saving opportunities from 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 leave you with a problem:

• Lower current (I) and the load will not operate correctly
• Reduce 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 a lot of 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 you’re 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 your 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.

To catch voltage regulation issues, use a Fluke 1777 Power Quality Analyser to look for transient voltages and voltage imbalance. 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.”

The additional heat causes cable runs, motor windings, and transformer issues. The overheating can cause significant damage or complete failure, either of which could lead to unplanned downtime and expensive repairs. To measure and diagnose harmonics, use a Fluke 1770 Series Three-Phase Power Quality Analyzer.

Unbalanced load

The additional heat causes cable runs, motor windings, and transformer issues. The overheating can cause significant damage or complete failure, either of which could lead to unplanned downtime and expensive repairs. To measure and diagnose harmonics, use a Fluke 1770 Series Three-Phase Power Quality Analyzer.

Benefits of Power Quality Studies

Once power quality studies reveal areas where energy is being wasted, you can take steps to fix the issues:

1. Set up a preventive maintenance routine so you can continue to measure against your benchmark and catch issues as they arise
2. Install harmonic filters on loads that add to your facility’s harmonic distortion.
3. Address the sources of unbalance. This may mean setting up a repair or replacement schedule for large motors with mechanical unbalance issues.
4. Mitigate unbalanced load issues. In some cases, this may mean adjusting single-phase loads to be more equally distributed across the phases.
5. Replace blown fuses where necessary. A blown fuse on a bank of three-phase power factor improvement capacitors could also cause the problem; simply replacing the fuse can resolve a major unbalance.

Power quality studies highlight much of what can be done to save energy, reduce energy losses due to issues throughout a facility, and lower energy costs.

Power quality monitoring can show where the issues you’re experiencing are coming from and how to fix them.

Beyond the energy savings, power quality studies have been shown to lead to some additional benefits:

• Discovering potential failure points in assets that can cause major disruption
• Mixed air temperature
• Came across improperly installed breakers prone to accidental tripping