Harmonic Cancellation

See also;   Acme Harmonic Mitigating Transformers & TEMCo Harmonic Cancellation Transformers

To Order Harmonic Cancellation Transformers & Systems We Recommend TEMCo Ph: 1-800-613-2290 Or 1-510-490-2187 Link: Harmonic Cancellation Transformers Link: Harmonic Cancellation Motor Generator Sets

Harmonic cancellation is performed with harmonic canceling transformers also known as phase-shifting transformers. A harmonic canceling transformer is a relatively new power quality product for mitigating harmonic problems in electrical distribution systems. This type of transformer has patented built-in electromagnetic technology designed to remove high neutral current and the most harmful harmonics from the 3rd through 21st.

Electronic nonlinear loads as the reason for the generation of harmonics. Nonlinear loads range from the little plug-in power sources to the massive automation equipment in factories. Harmonics slowly erode the electrical environment causing high maintenance, premature failures and fires. It is important that they are addressed.

1. What problems do harmonics create in a electrical distribution system??
   
   
   1. Large load currents in the neutral wires of a 3 phase system. Theoretically the neutral current can be up to the sum of all 3 phases therefore causing overheating of the neutral wires. Since only the phase wires are protected by circuit breakers of fuses, this can result in a potential fire hazard.
   
   2. Overheating of standard electrical supply transformers which shortens the life of a transformer and will eventually destroy it. When a transformer fails, the cost of lost productivity during the emergency repair far exceeds the replacement cost of the transformer itself.
   
   3. High voltage distortion exceeding IEEE Standard 1100-1992 "Recommended Practice for Powering and Grounding Sensitive Electronic Equipment" and manufacturer’s equipment specifications.
   
   4. High current distortion and excessive current draw on branch circuits exceeding IEEE Standard 1100-1992 "Recommended Practice for Powering and Grounding Sensitive Electronic Equipment" and manufacturer’s equipment specifications.
   
   5. High neutral-to-ground voltage often greater than 2 volts exceeding IEEE Standard 1100-1992 "Recommended Practice for Powering and Grounding Sensitive Electronic Equipment."
   
   6. High voltage and current distortions exceeding IEEE Std. 519-1992 "Recommended Practices and Requirements for Harmonic Control in Electrical Power Systems."
   
   7. Poor power factor conditions that result in monthly utility penalty fees for major users (factories, manufacturing, and industrial) with a power factor less than 0.9.
   
   8. Resonance that produces over-current surges. In comparison, this is equivalent to continuous audio feedback through a PA system. This results in destroyed capacitors and their fuses and damaged surge suppressors which will cause an electrical system shutdown.
   
   9. False tripping of branch circuit breakers.

How do harmonics affect a  site or facility?

Voltage distortion and voltage drop as mentioned in above items #3 and #6 cause the equipment connected to the branch circuit to draw more current to maintain the power rating (watts) of the unit. The bigger the current draw from the unit, the more it produces excess heat within the unit that was not factored for by its original design. In turn, the excessive heat causes premature component level failures within the unit. Additionally, you will experience computers locking up and other operational malfunctions that are unexplainable. Think about how many times we have experienced the "no problem found" syndrome with our computers! The excessive heat produced can directly contribute to downtime. Therefore, downtime is identified as any event that incurs or contributes to lost productivity, lost revenues, lost savings, and more importantly lost time. As we all have heard in the business world, "Time is Money".

In special facilities such as call centers or data centers, the excessive heat produced due to the large concentration of monitors and PCs will also cost  money in energy dollars. The air computer room (CRAC) or building air conditioning system will run longer or harder, therefore requiring more energy to maintain the desired temperature.

Telecommunications cabling is commonly run right next to power cables. If harmonics are above normal tolerances (more than 5% THD) as outlined in IEEE Standard 519-1992, then high frequency harmonics can be induced into phone lines and data cabling. The end result is noisy phone lines and unexplained data lose or data corruption in your LAN or WAN.

Why are harmonics unknown or untreated in electrical distribution systems?

First, one must understand that the electrical distribution system of most sites or facilities was never designed to deal with an abundance of non-linear loads. It’s a problem that has only recently begun to be recognized in the building industry. Within the last decade, the widespread use of computers and SMPS equipment is turning modern office buildings, factories, and industrial plants into high-tech computer environments. Even older buildings that are renovated are not retrofitted with modern harmonic treatment or cancellation. The end result is a building or facility unable to fully support today’s technology and the high-tech problems that it brings along with it. Obviously, given the problems harmonics can cause, it is imperative that today’s electrical distribution systems be designed for non-linear electronic loads, not just linear electrical loads. Unfortunately standard building codes and engineering designs do not meet the requirements of today’s technology. With the advent of newer SMPS equipment the harmonic problem will continue to get worse along with inadequate facility grounding.

 How can we wire electrical distribution systems for harmonics?

These are recommended ways to wire for the harmful effects that harmonics cause. However, these recommendations only keep the electrical distribution systems safe. These wiring recommendations do not eliminate or cancel high levels of harmonics.

 1. Use double-size neutral wires or separate neutrals for each phase.

2. Specify a separate full-size insulated ground wire rather than relying on the conduit alone as a return ground path.

3. On a branch circuit use an isolated ground wire for sensitive electronic and computer equipment.

4. Segregate sensitive electronic and computer loads on separate branch circuits all the way back to the electrical panel.

5. Run a separate branch circuit for every 10 Amps of load.

6. Install a comprehensive exterior copper ground ring and multiple deep driven ground rods as part of the grounding system to achieve 5 ohms or less resistance to earth ground.

7. Oversize phase wires to minimize voltage drop on branch circuits.

8. Shorten the distance on branch circuits from the power panel to minimize voltage drop.

The elimination of harmonics can be accomplished through a variety of techniques and applications. First, know that power factor correction capacitors do not remove harmonics. The inclusion of power factor capacitors can make the matter worse. Active filters are good, but are the most expensive and complex. Active filters digitally create and control reactive power to cancel the harmonics.

The most effective, basic method to take care of harmonics is through transformers. The principal is to take harmonics generated from separate sources, shift one source of harmonics 180 degrees with respect to the other and then combine them together; this will result in cancellation.

In a three-phase power distribution system, the 5th and 7th harmonics are the most predominant causes of distortion and heating problems. These harmonics  will easily cause standard distribution transformers to overheat, burn neutral conductors and naturally fail at the worst possible time.

Picture a sinewave, which contains the 5th and 7th order harmonics with the waveform. The K-Factor transformer shifts the 5th harmonic 150 degrees and the shifts the 7th harmonic 210 degrees. When the shifted harmonics return back onto the line, the shifted 5th will be approximately 30 degrees away from a perfect 180 degrees with respect to the non-shifted 5th. Likewise the 7th will be 30 degrees from 180 with respect to the non-shifted 7th. This is an excellent blend for these two most corruptive harmonics. Now, within the electrical distribution system, the shifted 5th harmonics are opposite in phase and cancel with each other, as do the shifted 7th harmonics.

In closing, it is important to consult with a power quality manufacturer before applying any of the recommendations or methods as discussed throughout this paper. A manufacturer consultant will be able to analyze the severity of the harmonics problem and design a plan tailored to your specific harmonics situation.
 

Power Transformer Sources: Power Transformer * Step Up Transformer * Step Down Transformer * Electrical Transformer * Isolation Transformer * Toroidal Transformer * Acme Transformer * High Voltage Transformer * Distribution Transformer * Transformer Manufacturer * Three Phase Transformer * Dry Type Transformer * 3 Phase Transformer * Cast Transformer * Voltage Transformers * Variac * Voltage Stabilizer * Voltage Regulators

 Power Transformer Information:

Power Transformer Manufacturer

• ACME Transformers - With Acme Electric being in business over 80 years, they have always believed in offering there customers superior service, quality and technical expertise in the transformer market.
• AMVECO Transformers - AMVECO designs and manufactures toroids transformers, current transformers, and auto transformers. Most AMVECO products are custom designed utilizing their state-of-art proprietary CAD programs.  The AMVECO engineers can quickly generate designs in a matter of hours, if needed.
• Federal Pacific Transformers -  Federal Pacific is a division of Electro- Mechanical Corporation, a privately held, American owned company founded in 1958. Federal pacific offers dry-type transformers from .050 KVA through 10,000 KVA single and three phase, up to 34.5 KV, 150 KV BIL with UL approval through 15 KV.
• Marcus Transformer - Ever since they opened their doors for business a half a century ago, they have been a leader in innovative transformer design. As a family-owned company they are proud of the reputation they have earned for making quality-built transformers that deliver exceptional performance and savings.
• Hammond Transformers -  Hammond Manufacturing was founded in 1917 in Guelph, Ontario, Canada. In the last 3 decades it has expanded to the US and the international markets offering many types of power transformers. 
• TEMCo Transformers - TEMCo Transformer, a family-owned business which has been manufacturing and distributing electrical products since 1968. They focus on transformers that significantly reduce power consumption over 30 percent compared to competitive makes.
• GE Transformers - GE has been a key player in the energy industry for more than a century.  Since the installation of their first steam turbine in 1901. They have become number one provider of high-technology power generation and distribution equipment.
• Jefferson Electric Transformers - Jefferson Electric has been a pioneer and innovator of magnetic products since 1915. Jefferson broad line of dry-type transformers are backed by quality assurance systems so stringent that each and every unit gets thoroughly tested before it goes out there door.
• More power transformer brands - Check out more companies by clinking this link.

 Power Transformer Types

• Distribution Transformers - Distribution transformers are generally used in electrical power distribution and transmission power. This class of transformer has the highest power, or volt-ampere ratings. and the highest continuous  voltage rating.
• Substation Transformers - Substation Transformers are large devices which usually weigh tens of thousands of pounds.   They are filled with tens of thousands of gallons of heat transfer fluid.  Although they are typically 99.8% efficient in the transforming of electricity from one voltage to another, processing hundreds of Mega Volts-Amps of electricity force the liberation of hundreds of BTUs per second.
• Medical Grade Isolation
   Transformer - Medical Grade Transformers generally refer to the transformers used in medical devices as well as hospital, biomedical and patient care equipment. There are a number of strict safety rules, guidelines and laws governing the design, construction and the test of these transformers.
• Drive Isolation Transformer - They are used to isolate a drive from a main power line to prevent the transmission of harmonics that the drives produce back into the power line.  They stop drive harmonics from disrupting computers and other sensitive equipment.
• Toroidal Transformers - Toroidal Transformers are more efficient than the cheaper laminated EI types of similar power level. Some of the advantages are smaller size, lower weight, less mechanical hum, (making them superior in audio amplifier), low-off-load loss.

• Starting Capacitor For use with single phase motors and gearmotor applications.
• Run Capacitor For use with 1 and 3 phase motors.
• Start Cap TEMCo offers a wide selection of start caps.
• Air Conditioner Capacitor For use with air conditioners.
• Replacement Capacitor Learn when you need to replace a capacitor and how to pick a new one.
• Motor Capacitor Need help with motor capacitor facts? Check out our FAQ here.
• Test Capacitor Need help with testing a capacitor? Check out our tutorial here.

Power Transformer Types

• Step-Up Transformers - A Step-Up Transformer is one whose secondary voltage is greater than its primary voltage.  This kind of transformer "steps up" the voltage applied to it. -
• Step-Down Transformers - A Step-Down Transformer is  designed to reduce voltage from primary to secondary.  They can range from sizes from .05 KVA to 500 KVA
• Isolation Transformers - An Isolation Transformer is a device that transfers energy from the alternating current (AC) supply to an electrical or electronic load.  It isolates the windings to prevent transmitting certain types of harmonics.
• Buck Boost Transformers - Buck Boost Transformers make small adjustments to the incoming voltage. They are often used to change voltage from 208v to 240v for lighting applications.  Major advantages of Buck boost transformers include; low cost, compact size and light weight. 
• High Voltage Transformer - There are many different types of voltage transformers. A High Voltage Transformer operates with high voltages. Typically, these voltage transformers are used in power transmission applications, where voltages are high enough to present a safety hazard.
• Medium Voltage Transformers - A Medium Voltage Transformer can be connected directly to a primary distribution circuit and generally has the most load diversity. These voltage transformers have installation practices that are generally in accordance with application recommendations from the Institute of Electrical and Electronic Engineers (IEEE).
• Low Voltage Transformers - A Low Voltage Transformer is an electrical device that transforms 120 volts (line voltage) into 12 volts or 24 volts (low voltage). Some uses for low voltage transformer are in landscaping lighting.
• Single Phase Transformers - In electrical engineering, single-phase electric power refers to the distribution of electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors.
• Three Phase Transformers - Three Phase Transformers must have 3 coils or windings connected in the proper sequence in order to match the incoming power and therefore transform the power company voltage to the level of voltage needed while maintaining the proper phasing or polarity.
• Custom Transformers - Custom Transformers are designed for a certain performance specifications and size requirements.  The company works with your engineering specification. 
• Industrial Control Transformers - Industrial Control Transformers are used to convert the available supply voltage to the required voltage to supply industrial control circuits and motor control loads.
• Pad Mounted Transformers - Pad Mounted Transformers are usually single phase, or three phase, and used where safety is a main concern. Typical applications; restaurant, commercial building, shopping mall, institutional. 
• Pole Mounted Transformers - Pole Mounted Transformers are used for distribution in areas with overhead primary lines. Outside a typical house one can see one of these devices mounted on the top of an electrical pole.
• Oil Filled Transformers - Oil Filled Transformers are transformers that use insulating oil as insulating materials.  The oil helps cool the transformer. Because it also provides part of the electrical insulation between internal live parts, transformer oil must remain stable at high temperatures over an extended period.
• Dry Type Transformers - Dry-Type Transformers are available for voltages up through 34.5 kV (although the most common upper limit is 15) and KVA ratings up through 10,000 (with 5000 as the usual limit). Dry-type use air as a coolant, lowering health and environmentally concerns.
• Auto Transformers - An Autotransformer is an electrical transformer with only one winding. The winding has at least three electrical connection points called taps. Autotransformers are frequently used in power applications to interconnect systems operating at different voltage classes, for example 138 kV to 66 kV for transmission. Another application is in industry to adapt machinery built for 480 V supplies to operate on the local 600 V supply.
• More power transformer types - Read further about additional transformer types and their uses.

 Power Transformer Term Definitions

• Electrical Transformers - Electrical Transformers are devices used to raise or lower the voltage of alternating current. For instance, power is transported over long distance in high voltage power lines and then transformers lower the voltage so that the power can be used by a business or household.
• Isolating Transformers - An Isolating Transformer is a transformer, often with symmetrical windings, which is used to decouple two circuits.  An Isolation transformer allows an AC signal or power to be taken from one device and fed into another without electrically connecting the two circuits. Isolation transformers block transmission of DC signals from one circuit to the other, but allow AC signals to pass. 
• Transmission Power Lines - A Transmission Line is the material medium or structure that forms all or part of a path from one place to another for directing the transmission of energy, such as electromagnetic or acoustic waves as well as electric power transmission. Components of transmission lines include wires, coaxial cables,  dielectric slabs, option fibers, electric power lines, and waveguides.
• Transformer Voltage - The measure of the amount of force on a unit charge because of the surrounding charge.
• Transformer Phase - Most transformer are either single phase or three phase.
• Transformer Frequency - The transformer cannot change the frequency of the supply. If the supply is 60 hertz, the output will also be 60 hertz.
• Transformer K Factor - Some transformers are now being offered with a k-factor rating. This measure the transformer's ability to withstand the heating effects of non-sinusoidal harmonic currents produced by much of today's electronic equipment and certain electrical equipment.
• Primary Voltage - The coil winding that is directly connected to the input power.
• Secondary Voltage - The coil winding  supplying the output voltage.
• Harmonic Cancellation - Harmonic cancellation is performed with harmonic canceling transformers also known as phase-shifting transformers. A harmonic canceling transformer is a relatively new power quality product for mitigating harmonic problems in electrical distribution systems. This type of transformer has patented built-in electromagnetic technology designed to remove high neutral current and the most harmful harmonics from the 3rd through 21st.
• Weatherproof - Enclosed transformers come with a weatherproof standard set by NEMA.
• Epoxy Encapsulated - A process in which a transformer or one of its components is completely sealed with epoxy or a similar material. This process is normally preferred when a unit might encounter harsh environmental conditions.
• More power transformer terms - Such as inductor, ground fault, core saturation, current transformer, faraday shield, etc.

Related Transformer Products

• Voltage Regulators - A Voltage Regulator is an electrical regulator designed to automatically maintain a constant voltage level.  It may use an electromechanical mechanism, or passive or active electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
• AC Line Reactor - AC Line Reactors is a three phase transformer used in conjunction with AC variable frequency and DC motor drive. They are a bi-directional protective filtering device.
• Line Power Conditioners - Power or Line Conditioners regulate, filter, and suppress noise in AC power for sensitive computer and other solid state equipment.
• DC Power Supplies - Conversion of one form of electrical power to another desired form and voltage. This typically involves converting 120 or 240 volt AC supplied by a utility company to a well-regulated lower voltage DC for electronic devices.
• Rotary Phase Converters - Rotary Phase Converters are commonly used in home or small commercial or industrial settings. Rotary phase converters convert single-phase power into three-phase power. This is a very cost-effective way to power three-phase electric motors and other three phase equipment.
• Frequency Converters - A Frequency Changer or Frequency Converter is an electronic device that converts alternating current (AC) of one frequency to alternating current of another frequency.
• Voltage Converters - A Voltage Converter changes the voltage of an electrical power source and is usually combined with other components to create a power supply.
• Magnetic Motor Starters - Magnetic Motor Starters are essentially heavy duty relays mounted in boxes, often equipped with heater/thermal overloads matched to the motor they start.
• Motor Starting Auto Transformers - An Auto Transformer starter uses an auto transformer to reduce the voltage applied to a motor during start. The auto transformer may have a number of output taps and be set-up to provide a single stage starter, or a multistage starter.

For an additional resource the Best of Industry Web Directory : Electrical Power Transformer Directory section is quite useful.