Distribution System Efficiency

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Electrical Distribution Systems are Inherently Inefficient

AC Motors, also known as Inductive Loads, consume as much as 80% or more of the total energy in a manufacturing plant. To do work, AC motors require a supply of 2 types of energy or “Current” (“I”); Real (Active) Energy and Reactive (Apparent) Energy. Real Energy is consumed as motors do work. Reactive Energy is required during every alternating cycle for the inductance of motor windings that motors need to rotate and do work. However, Reactive Energy is not consumed so it is released by the motor during every alternating cycle when some is stored in the downstream distribution system but much of it dissipates as “waste” in the form of heat losses. Reactive Energy is measured as Volt Amperes Reactive, or VAr.

Typical Industrial Distribution System

Microsoft Word - 120723 Legacy Performance Evalution Report - Mu

Electric motors, in their natural state, draw 20-25% more current from the generating plant than is actually consumed by them. This obviously increases kW Demand billing by 15-20% and also causes exponentially increased transmission resistance (I2R) and heat stress on the Electrical Distribution System which can cause a 10% or higher increase in billed kWh energy consumption.

Reactive Energy Correction

We can save significant electrical consumption and waste by reducing the current drawn by inductive loads. By installing a customized capacitive device (LegacyLiner) near the load, the reactive current released by the motor is temporarily captured and stored and then released back to the motor during the next cycle. Thereby we can provide a “recycling” benefit for Reactive Energy and reduce the total current supplied through the distribution system which exponentially reduces losses (I2R)

Legacy improves Distribution System efficiencies

Microsoft Word - 120723 Legacy Performance Evalution Report - Mu

Legacy EnerSave achieves Energy Savings by installing a LegacyLiner as close as possible to the operating motor load. The Liner is custom-matched for the exact VAr needed for the motor to operate optimally. For standard electric motors, the Liner is installed on the “load side” where it is energized whenever the motor operates. For motors equipped with soft-starts or other electronics, the Liner is installed on the “line side” and it is activated by using a contactor only when the motor operates. There are no moving parts and useful life is estimated to exceed 20 years.

The positive benefit of the Liner is immediate after installation. The net benefit is a 15-25% reduction in distribution system current and the associated reduction in kW Demand billing.  Reduced resistance, heat and waste result in overall kWh Energy Savings of as much as 10 - 12% or more.

Proven Energy Efficiency Legacy has thoroughly measured and verified the results from Liner installations at a large number of project sites. Table 1 below shows a summary of the “line-side” changes in electrical conditions as measured at 3 different installation sites. The improvements in electrical supply conditions and energy efficiency are abundantly evident. Savings TableThe kWh energy savings are a result of a reduction in Distribution System Losses and increased motor efficiency. Pumps Average kWh/m3 was reduced by 7.32%. With annual flow of 4.5 Million m3, this will save 54,000 kWh, a saving of as much as $7,020 per year. Average kVA reduction of 23.5% and average Power Factor increased from 0.74 to 0.94. This reduces monthly Peak kW Demand by an estimated 70-76 kW, a saving of up to $9,500 per year. Reduced Operating and Maintenance Costs In addition to energy savings, lower loading of the electrical distribution system and improvements in Power Quality results in these other benefits:
  • Improvements in the electrical supply such as higher and more stable voltage with fewer sags;
  • Reduced Harmonics and reduced breaker tripping and electronic equipment failure;
  • Extended capacity and life of transformers, contactors and all other electrical components.
  • Electric motors and drives that operate closer to design specifications are more efficient, reducing energy use, down-time and maintenance.
kWh Energy Savings and Operational savings that are achieved by Reactive Energy Correction tend to be larger than any that can be achieved by implementing other types of measures.   back to top