Why Is Power Quality Important?

It is most desirable for electrical and electronic equipment to operate from a clean, sinusoidal voltage and current waveforms in order to achieve maximum efficiency. Sources of disturbances that can combine with the sinusoidal waveform are listed as follows:

  1. Reflections arising from reactive switching.
  2. Arcing from corrosion voltage breakdown.
  3. Induced EMI/RFI
  4. Harmonic currents arising from unbalanced or nonlinear loads.

In a power line system, any time a circuit which contains a reactive load is opened or closed by contactor actuation (switching on and off), a high frequency transient appears on the line. The voltage level of that transient can be many orders of magnitude higher than the nominal line voltage. The transient will contain a ringing tail, and contain a multitude of high frequency components. In turn, the high frequency components induce eddy currents in the magnetic cores of transformers, motors,  and generators. Thus, hysteresis power losses develop via heat buildup in the core. Overall, efficiency is measurably reduced. In a magnetic core, when AC current flows in the copper winding around the core, a magnetic field is created resulting in flux in the core. If the frequency of the current is only the pure fundamental 60Hz, then the flux density versus magnetizing force traverses a single path line, and is maximally efficient. However, when the magnetizing current contains frequencies higher than 60Hz, hysteresis occurs because these high frequency components operate with varying phase shifts between the current and driving voltage, resulting in transverse action. This action literally takes up space in the core, and is viewed as eddy swirls like that in a stream of water. Energy is lost in heat proportional to the width of the hysteresis cycle. Over a period of time the heating effect in the core will result in deterioration and eventual breakdown.

Another problem associated with high frequency noise in the power system is that of "skin effect". Skin effect in a conductor carrying an alternating current is the tendency toward crowding the current into the outer layer or "skin" of the conductor, owing to the self-inductance of the conductor. Basically, an increase in frequency causes non-uniform current density, resulting in an increase in the effective AC resistance of the conductor (and decreases its internal inductance). This is due to the fact that there are induced EMF's in a conductor in which there is alternating flux. These EMF's are greater at the center than at the circumference, so the potential difference tends to establish currents that oppose the current at the center and assist at the circumference. The current is then forced to the outside of the conductor, further reducing the effective area of the conductor. This results in an increase of the effective resistance of the conductor and a lower current rating for a given temperature rise.

High frequency noise always results from some type  of disturbance in the system, and will radiate from its' point of origin and propagate electromagnetic and radio frequency interference through the system. The wires act as antennas, coupling the energy not only to the loads, but also back to the source. This broad spectrum of energy will induce Eddy currents in every magnetic core, thus displacing to some extent the 60Hz power that otherwise would exist. As indicated before, every bit of energy occurring in the spectrum above 60Hz adds to the dissipation of available power, thus reducing efficiency and causing a deterioration in the overall system.

Another area of concern, particularly in a 3-phase power system, is the development of harmonic energy appearing at odd harmonics of 60Hz. As loads are unbalanced or nonlinear, a neutral current occurs. This unwanted current simply adds to the losses due to copper resistance due to the skin effect noted above. Heating occurs, and the effect of loss multiplies upon itself in the system.

The EP products act upon these disturbances by tracking, filtering, and absorbing the high frequency anomalies, thus presenting to the load a clean sinusoidal wave. Over time the resulting increase in efficiency gives rise to increased productivity and lower operating costs.

There are several issues that can be easily addressed to improve the overall Power Factor and quality of any electrical system. This paper looks at the ones that appear to have the most detrimental effects on environmental control units used for the poultry industry while offering solutions & improvement:

  1. GROUNDING. A low resistance ground is imperative to both surge protection designs and power quality. A regular check and upgrade (as needed) of grounding systems will reduce interference and line noise, improve power factors, reduce the risk of accidental electrocution, help decrease potentially damaging harmonics, and improve the efficiency and durability of surge protection equipment. Grounding will be covered in depth in the next section.
  2. ELECTRICAL TUNE-UP. An electrical tune-up consists of a periodic inspection and improvement of an existing system. Check grounding. Verify and tighten all connections, including Lines, Neutral, and Ground at panels, breakers, disconnects, switches and receptacles. Clean up any corrosion on connections. Verify breaker integrity (IR check). Replace worn, broken, or damaged components as needed.
  3. TVSS (TRANSIENT VOLTAGE SURGE SUPPRESSION). A properly designed and installed Softclamping™ surge protection system provides three critical power quality functions.
  • Obviously, it will reduce potential damage from spikes and surges caused by lightning, inductive loads, and utility “glitches” (including major events like a grid-shift, as well as the daily issues of capacitor switching and temporary “crossover”).
  • Additionally, since TVSS Softclamping™ systems incorporate filtering in the internal components, low level surges, line noise, and RFI/EMI will be reduced, or eliminated. This will lower the number of electronic “hiccups” a system experiences and increase the life of the equipment that is being protected.
  • Subsequently, a Matrix Energy System™ using Softclamping™ TVSS will reduce these problems with an added benefit of increasing industrial electric consumers power factor, which in and of itself increases the use efficiency of electricity within the grid.By following the simple, inexpensive procedures listed herein, the industrial electric consumer can reasonably expect to see noticeable reductions in system downtime, an improved performance from all electronic equipment with hidden rewards of a calmer more efficient electrical grid.  An added benefit will be an increase in the industrial electric consumer’s Power Factor and a return of investment that enhances electrical consumer’s bottom line, independently documented by the United States Navy.