Manage Your Electric Bill By Managing Voltage

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Manage Your Electric Bill By Managing Voltage

By Greg Wiegand, founder of MicroPlanet - 12/21/2009
If you are like most people, the extent of your knowledge about electricity is you either have it or you don't. When you don't have electricity the voltage is zero. When you have it, the voltage averages around 120 volts. However, in between those two extremes are imperceptible differences in voltage that affect your electricity bill.

This is not common knowledge, and if you ask your local utility representative they will most likely tell you it does not make any difference. It's not that they are trying to mislead you; it's just that they don't have any way of controlling the voltage to individual customers, so they won't pay any attention to it as long as it's within their allowable range. In the USA, the allowable voltage delivery range is 114 V to 126 V, and voltage rises and falls on a daily cycle. For most customers, the average voltage is between 120 and 121 volts, and customers close to the substation will have a higher average voltage than those at the end of line. This is the physics of how electricity works.

For example, If you had two identical stores -- one near the utility substation (high voltage) and one at the end of a feeder line (low voltage), the energy charges for the store near the substation would typically be between 6 percent and 10 percent higher than the other store, even if its an identical business.

Considering electricity is usually the second highest expense for a convenience store operation, voltage represents a variable expense that should be managed.

Managing your voltage will save you money.

Why does this happen? Without getting too technical, it basically boils down to the fact that losses in electrical devices are largely proportional to the voltage. As an electrical appliance converts electricity into light or some form of work, a percentage of the total energy is lost in the conversion process causing the device to heat up. Higher voltage increases these conversion losses, which is converted into waste heat, increasing your bill.

Why is extra heat a problem? The primary issue is the additional heat decreases the life of your equipment. A rule of thumb in engineering is that whenever you raise the operating temperature of an electrical device 10°C, you cut the lifetime of that equipment in half. Small motors common to convenience stores, will typically increase their operating temperature by 8°C when the voltage increases from 114 to 126V. The higher the voltage, the higher the maintenance costs. Secondarily, in the summer the extra wasted heat increases your air conditioning load. In the winter it may appear to be beneficial; however, other forms of space heating are more cost effective than resistive electric heat, and they don't reduce the operating life of your equipment.

How can voltage be managed? There are new kinds of high efficient buck/boost voltage regulators, which offer unique qualities making them perfect for this application. These voltage regulators are not power factor correction devices. They are high efficiency, precision voltage regulators. For 120 V systems, the ideal voltage is 114 V as long as the voltage is dynamically regulated and held precisely at 114 V. The standard for utility voltage delivery in North America is anywhere between 114 V to 126 V.

Many electricians will tell you that 114 V is too low because they know the utility voltage changes significantly throughout the day. If your utility voltage averages 114 V, that means sometimes the voltage would be higher and sometimes it would be too low, which will damage your equipment. However, this is a distinctly different situation than having dynamically regulated voltage held constant at 114 V.

What else happens when you regulate utility voltage? Regulating the incoming voltage reduces three-phase voltage imbalance, one of the leading causes of three-phase motor overheating and failure. Managing each phase independently optimizes motors efficiency and extends their usable life. Voltage regulation also provides transient protection, which protects internal loads from quick high voltage spikes. Another advantage is process control. Voltage sensitive equipment, such as slushy dispensers, will put out a consistent product because the voltage is not fluctuating throughout the day.

If this is a good idea, why isn't it common practice? Obviously voltage regulators have been around a long time in one form or another. Most voltage regulation technologies lose 3 percent to 6 percent of the energy that goes through them, making them impractical for this application. Other voltage regulation technologies are efficient; however, they distort the voltage sine wave. This is not good for your equipment or the utility.

Advances in technology and optimization of the design have produced voltage regulators, which can average a loss of less than 1 percent. Not only are the new regulators efficient, they have fast response, high accuracy and no voltage distortion. They are ideally suited for improving power quality and the electrical efficiency of convenience stores and lowering their overall utility usage.

Greg Wiegand is a founder of MicroPlanet and one of the inventors of MicroPlanet’s technology. He was a research engineer with LifeSpan BioScience and the founder of Zero Gravity Inc., a company that provided electro-mechanical design and technology development services for the motion picture industry. Wiegand acted as the lead design engineer and project manager, directing multiple consulting engineers on various projects ranging from motion control in the special effects field to specialty lighting projects. He has been granted numerous patents related to his projects.