All Power is NOT Created (or Used) Equally
Power quality refers to the ability of electrical equipment to consume the energy being supplied to it. A number of power quality issues including electrical harmonics, poor power factor, voltage instability and imbalance impact the efficiency of electrical equipment. The consequences of these include:
- Higher energy usage and costs
- Higher maintenance costs
- Equipment instability and pre-mature failure
It is critical that power quality be assessed as part of any energy management strategy. Generally, power quality issues fall into three somewhat broad categories.
- Poor power factor – refers to an excess of reactive power in the system. This reactive power does not perform any real work and as such is wasteful and costly. Power Factor Conditioning (PFC) reduces and can almost eliminate this reactive power and thereby reducing energy costs, stop equipment overheating problems, nuisance tripping and even motor failures.
- Harmonic voltages and currents – are introduced by a range of common electrical devices which distorts the AC wave form supplied and increases power usage. By introducing harmonic filters (or reactors) the harmonics are eliminated and the result is more efficient power usage and cost savings.
- Voltage instability – is in part a side effect of the high or low voltage electricity supply from the network. High voltage does not increase equipment power, but instead is detrimental to equipment performance and longevity. Low voltage can cause brown outs and reduced productivity. Voltage optimization ensures the voltage supplied to the system is stable as required by the equipment.
Power Factor Explained
To understand power factor, visualize a horse pulling a railroad car down a railroad track (as illustrated below). Because the cross braces between the railroad ties are uneven, the horse must pull the car from the side of the track. The horse is pulling the railroad car at an angle to the direction of the car’s travel.
The power required to move the car down the track is the working (real) power. The effort of the horse is the total (apparent) power. Because of the angle of the horse’s pull, not all of the horse’s effort is used to move the car down the track. The car will not move sideways because of the steel rails; therefore, the sideways pull of the horse is wasted effort or nonworking (reactive) power.
The angle of the horse’s pull is related to power factor which is defined as the ratio of real (working) power to apparent (total) power. If the horse is led closer to the center of the track, the angle of side pull decreases and the real power approaches the value of the apparent power. Therefore, the ratio of real power to apparent power (the power factor) approaches 1. As the power factor approaches 1, the reactive (non-working) power approaches 0. Both of these are optimum power scenarios.
Negative Effects of Low Power Factor
Many utilities penalize their customers when the power factor drops below a certain predetermined level (i.e., levels of .9 or .95 are common penalty thresholds). Utility customers are then billed for this discrepancy based on how low the actual power factor is measured at the metering point during any given month. Low power factor also reduces a company’s electrical system distribution capacity by increasing current flow and causing voltage drops.
Bulk power factor correction is a tool that electrical utilities and plant engineering personnel use to improve the KVAR (Kilovolts-Amps Reactive) within a facility. This is usually accomplished by adding capacitor banks to raise the power factor value at the facility being serviced. Reactive energy provided from the capacitor bank will offset the opposing inductive loads created by motors, transformers, lighting ballasts, or other inductive loads. Placement of the capacitor bank determines who benefits from the power factor correction. Placement of the bank before the meter benefits the power supplier. Placement of the bank after the meter benefits the consumer.
Bulk correction does not necessarily address the low power factor problem by itself. Static correction involves placing smaller Power Conditioning nearer to the actual electrical equipment. This allows for better power factor improvement for individual inductive loads. Because of improvements in decreasing heat losses associated with I2R line loses (Power Loss = Current2 x Resistance), it will also reduce actual kW consumption as well. Out of phase I/E (current/voltage) waveforms create heat losses on the same conductor. When the I/E waveforms are adjusted to closer operating tolerance, the heat losses (created by opposing energy transfers) will be reduced on that particular line, resulting in greater potential for kW savings.
It might be concluded that power factor correction by itself may be a great way to improve electrical energy usage, but there are some draw backs to the bulk methods.
- A harmonic is identified as a multiple of the fundamental frequency (60 hz). One main disadvantage is that odd harmonics (especially 3rd, 5th, 7th and 9th) are generated and much of the time amplified by capacitors, while at the same time working against various inductive loads. Even numbered harmonics need not be discussed as they tend to cancel out and are less of an interference problem. Odd harmonics (especially the 3rd and 5th) tend to generate excessive heat and thus can actually shorten service life of inductive equipment. They often also interfere with sensitive electronics in motor controllers associated with VFDs (variable Frequency drives) and soft start equipment.
- Capacitors are costly. Many capacitor systems are sold with a Return on Investment (ROI) conservatively figured between 8 to 10 years.
- Capacitors, when used in a power factor configuration, have no transient or surge suppression capabilities. Surges and transient voltages actually can be amplified by capacitors and offer the customer no benefit to these adverse effects or damages caused therein.
- Capacitors tend to self-destruct over a short amount of time, although the newer capacitors tend to hold up a bit longer under adverse line conditions. The internal dielectric material can only take so much rapid discharge punishment before the device will arc through and discontinue working, either partially or entirely. The average life expectancy of a typical capacitor is 8 years, which is about the same time the device finally pays for itself.
Overview of the Power Correction Unit Technology
The Power Conditioning Unit is designed and built to provide reliable and sustainable power filtering, surge suppression and harmonic filtering in a single device. Working together as a system, the result of this Power Conditioning Unit (PCU) technology is greatly improved power quality to end user loads (i.e., rotating motors, compressors etc.). In addition, the 3- phase PCU is designed to work on any voltage, from 110V up through 480V. This sets Power Conditioning Unit PCU apart from all other previous products that typically address just one aspect of power line quality. Based on directly sub-metered installations, the Power Conditioning Unit PCU technology provides monthly electric energy cost reductions which normally average 10% or more. Some installations have reported reductions of 18-20% or more in total energy costs.
When compared to the cost of regular power factor correction, as stated further above, load bank capacitors have a much higher ROI than Power Conditioning Unit, which has an average ROI of about 18
months when correctly engineered and subsequently installed. With an average 10-year equipment life under normal use, Power Conditioning Unit PCU delivers the end user a long-term ROI of 650% or more.
Once the appropriate Power Conditioning Unit PCU has been engineered for each application, installation is relatively easy. A licensed electrician can usually install a device in under 30 minutes. Once installed, savings are realized immediately. Since the device is installed in parallel to the existing inductive load, if the Power Conditioning Unit PCU would ever fail, the inductive load continues to receive power and operate. It just reverts back to using the same dirty power it did before.
Details of Enhanced Power Filtering
The Power Conditioning Unit PCU integrated Enhanced Power Control Unit approach to achieving electrical energy cost savings for customers overcomes the issues associated with bulk Conditioning. The individual components of the Power Conditioning Unit PCU design include:
- Harmonic Filtering/Blocking
- Voltage Surge Suppression
- Proprietary circuitry allowing individual components to work together more effectively
The patented Power
Conditioning Unit PCU system gathers
the back electromagnetic flux generated by the motor.
VARs (Volts-Amps Reactive), phase matches it, filters the power harmonics, first stores and then releases the power stored in the capacitors for use by the load. This proprietary process ultimately reduces the amount of electric power drawn from the utility while improving the power factor at the meter.
Power Conditioning Unit PCU also comes with special line filter conditioning features to reduce harmful harmonics. Part of the internal circuit board design is dedicated to filtering out and reducing the odd harmonics associated with the harmful effects produced in the CEMF (counter electromagnetic force). These CEMF’s are produced by inductive loads working in conjunction with power Conditioning. Because excessive heat is the biggest enemy of nearly all types of equipment, by reducing the temperature of the downline operating motor by 3 – 5 degrees F on average, equipment life is extended up to 20% or more.
Power Conditioning Unit PCU also incorporates surge and transient voltage components with highly reliable, state- of-the-art voltage surge suppression components. These unique features attenuate (reduce) line noise and voltage spikes associated with surges and transients. Normally line transients and surges are dispersed as excess heat in the inductive loads, thereby shortening the service life and using more energy to run. Power Conditioning Unit PCU reduces this problem considerably.
Because Power Conditioning Unit PCU devices are “Enhanced” with voltage surge suppression and line filtering components, the power factor capacitors are better protected against early failure, hence the term “Enhanced Power Control Unit”. Early or premature failure occurs when the dielectric breaks down in normal power factor correction capacitors. Power Conditioning Unit PCU employs the finest, self- healing capacitors available in its design.
Power Conditioning Unit Delivers Tangible Results
The Power Conditioning Unit PCU can reduce utility costs even when a given power factor is already high, even as much as .95. A more common scenario however is demonstrated in the example below.
An inductive load with a power factor of .70 requires 142 KVA to deliver 100 KW for consumption, while an inductive load with a power factor of .95 requires only 105 KVA to deliver the same 100 kW for consumption. Since KVA is the measurement used to calculate utility demand charges, lowering KVA will also lower demand charges proportionately.Follow Us on Social