If a fault is detected by the PQconnect board, what response is taken by the board?

For some faults, the tuned circuit contractor can be configured to open on a fault condition, specifically for tuned circuit line reactor overloads.

In other circumstances, the fault detection is informational only such as the line reactor overload. In the case of a line reactor overload opening the tuned circuit contactor can make the overload worse as it forces harmonics flowing into the tuned circuit to instead flow through the line reactor.

Why did TCI name the KMG filter “MotorGuard”?

TCI designed and developed the sine wave filter to correspond with the industry’s demand for a High Performance Output Filter. This filter must improve the power quality and greatly reduce the effects of dv/dt on motor applications. The term “MotorGuard” signifies the function of guarding the motor from damaging voltage distortion that has been known to cause premature motor failure.

Does TCI have any unique success stories using the KMG filter?

TCI has widely used these filters in deep well pumping applications. They are successfully operating in Canada, the US and Central/South America on oil and gas exploration and pumping operations. This filter has allowed the use of modern low voltage drives with step-up transformers and custom designed medium voltage motors in extremely long lead applications to accomplish tasks never before possible with standard low voltage drive technology. Please contact your TCI representative for more details.

Does the KMG High Performance Output Filter have an effect on motor shaft bearing currents?

Yes, by virtue of attenuating the high frequency components present in the PWM wave form and producing near sinusoidal voltage at the motor terminals, the amount of common mode current flowing through the motor bearings is greatly reduced. There is also a reduction in the amount of EMI when the KMG is installed.

How do I size the KMG filter?

We have selection charts listing nominal horsepower ratings with maximum continuous current ratings. If you have non-standard motors or motors other than NEMA design B with high full load amp ratings, you can use the actual motor nameplate FLA for making the selection. Contact your TCI distributor or representative if the current rating is in question.

How does the KMG vary from a dv/dt filter or line reactor on the output side of the VFD?

The V1k dv/dt output filter is designed to limit the peak voltage to approximately 1,000 volts. These filters are successful in most simple drive/motor applications where lead lengths are about 1,000 feet or less, and a modulated output waveform is acceptable to the load. In terms of a line reactor, the inductive reactance achieved with a line reactor works to slow down the rise time of the spike but can do nothing to limit the magnitude of it. The MotorGuard goes beyond this to eliminate the carrier frequency effects in the modulation process. The result is a smooth sinusoidal waveform and load friendly power supply.

How will the KMG filter protect my motor?

The filter eliminates the effects of dv/dt on the motor insulation by removing the high frequency voltage distortion generated by the drive output power semi-conductors. The modern variable frequency drive has revolutionized the use of the conventional squirrel cage induction motor; however, current drive topology can contribute to insulation problems in the motor. The KMG greatly attenuates the carrier frequency voltage distortion and lowers the level of line distortion.

What are the environmental limitations of the KMG filter?

Like most electronic equipment, heat, humidity, high elevations, and dirty environments require special considerations. The KMG Industrial filter is designed for use in protected indoor environments similar to the standard drive. Normal indoor industrial environments are specified as having a maximum ambient temperature of 40 degrees C and are protected from dirt and moisture. The KMG General Purpose filter is designed for the NEMA 1 indoor and NEMA 3R outdoor enclosure. Please contact your TCI distributor or representative if additional application assistance is required.

What benefit does the KMG filter with the board option provide?

The KMG output filter is an L-C-R, low pass filter. This is a tuned filter which combines inductance, capacitance, and resistance. Along with these fundamental components, the filter contains an optional protection monitor board. This board ensures that the filter is providing adequate dv/dt and peak voltage protection and includes a fault alarm relay for customer use. For more detailed information, please refer to the Installation, Operation and Maintenance Manual.

What level of voltage distortion can I expect from the output of a KMG?

The objective of the filter is to duplicate the efforts of typical power utilities. According to utility standards, the power quality is to limit voltage distortion to approximately 5%. The MotorGuard filter follows that challenge but limits voltage distortion to between 5 and 7%. This is well within the operating standards of any conventional squirrel cage induction motor. It is well accepted by any standard transformer as well should the load to the filter be a transformer.

What are the required drive settings to use the V1K?

Similar to the KLC, the V1K is designed for use on modern PWM drives with a diode front end power structure. While being the latest in drive technology, these fast switching electronic drives have been found to produce a high amount of dV/dt or voltage distortion on the output voltage waveform. To operate the drive and motor properly, we recommend the drive carrier frequency be adjusted to 8 kHz or less and the drive be operated at an output frequency of 60 Hz and lower. The manual can assist with the other system considerations required.

Will the output waveform of the V1K look like a sine wave?

The V1K is a very effective dV/dt filter and will provide excellent protection for your motor when use on a PWM, variable frequency drive. The output waveform will show a notable reduction in the magnitude of the voltage excursions found on a conventional drive output waveform. It is designed to limit the voltage spikes to 1000 volts per u Second or less and our tests indicate it is very effective at that goal. It is not however, a sine wave filter and it does not return the drive output square wave to a smooth sine wave profile. For this type of performance on the output of the VFD, we recommend you consider using the TCI, KMG MotorGuard Sine Wave Filter.

Should long-lead filters be “carrier stripping” devices?

No. It is not the PWM carrier energy that is causing premature insulation breakdowns in motors, it is the high overshoot voltage due to resonance (or wave reflection). Carrier stripping is an old idea with drawbacks such as high losses, large size, and undue stress on the inverter. Carrier stripping filters require huge amounts of capacitance and inductance, both of which cause problems. The inverter will have to supply large amounts of capacitive current each time it switches, and motor terminal voltage will be reduced at the fundamental frequency, resulting in degraded torque per AMP characteristics and dynamic motor response to changes in the load. Also, the impedance decreases the velocity factor of the wire, resulting in poor dynamic response of the motor. The V1K output filter is designed to minimize the impact of the filter on overall system performance (with respect to both torque/AMP and dynamic response concerns). It simply rounds the steep edges of the switched voltage in order to prevent against overshoot, and system losses are held to an almost imperceptible minimum. In addition, it’s a lot less expensive.

Are there special applications where I can’t use the KMG filter?

The MotorGuard High Performance Output Filter is designed to work on a variety of applications where the power quality of the drive output needs conditioning. It is most commonly used for motor applications involving very long lead lengths, multiple motors, power supplies for test equipment, or inputs for a step-up transformer. Care should be taken when using the filter on vector drives, due to the feedback loop from the motor to the drive. In some instances, the KMG filter is not compatible with a vector drive. If you have a unique application, please see your TCI representative or contact the Technical Support Group at TCI.

Can I get the KMG in outdoor cabinets?

The KMG Industrial filter is available in both Open Panel designs and NEMA 1 general application industrial indoor enclosures. The KMG General Purpose filter is available in NEMA 1 and NEMA 3R enclosures. TCI would be happy to assist you with the mounting of an open panel design into an enclosure of your choosing. For additional assistance, contact the TCI Technical Support Group.

Can I incorporate the KMG filter into my drive cabinet or MCC?

It is quite common to specify the KMG MotorGuard in an open panel design and install it in an open bay of the drive cabinet. TCI has worked with drive manufacturers to develop a standard set of back panel dimensions that easily incorporate into many standard drive cabinets. Please see filter dimensions and watts loss information on the TCI web site for use in your application.

Can I test a KMG and return it if I’m not satisfied?

If your specific application is discussed in advance with a TCI representative, a trial application can be arranged. If the performance of the product is in question, your TCI distributor or representative will assist you in your application. It is the intent of TCI to ensure the successful operation of the filter along with a long service life. If you purchase any TCI product, and you are not satisfied, feel free to return the product for full credit.

Can TCI guarantee the performance of the KMG filter?

TCI guarantees the output of the MotorGuard filter to greatly improve the quality of the drive output power. While drive output power does vary slightly from drive manufacturers, TCI has designed the filter to achieve near sine wave power. The outcome is guaranteed to be suitable for all standard NEMA design motors. Refer to the web site for specific Performance Guarantee information.

Do I have to buy a special drive to work with the KMG Filter?

TCI has designed and tested the MotorGuard filter with technical input from the major drive manufacturers as well as actual lab testing to ensure compatibility. TCI cannot be responsible for ongoing changes in drive topology. To date, the filter has been successfully operated with a multitude of drives. TCI feels confident the filter will be compatible with all major drive topologies. If the filter fails to function due to drive topology incompatibility, TCI will accept return of the filter for full credit.

Do I have to set up my standard drive in a special way to work with the KMG?

The KMG requires the drive to have a carrier frequency of between 2 and 4 kHz. If the drive has a variable carrier, the average operating frequency must remain between 2 and 4 kHz. The drive should be operated in scalar mode. The maximum drive output operating frequency must be 80 Hz or less. There are no special drive requirements or modifications necessary for the successful operation of the KMG filter.

Do you have customers who have standardized the KMG for the output of long lead applications?

TCI has collaborated with major drive manufacturers as well as equipment companies to install these filters. Drive OEMs, as well as Pump, Drilling equipment, HVAC and other equipment manufacturers are utilizing the TCI filter for successful system operation. Contact your local TCI representative for more application information.

Can I use the V1K on a single-phase voltage input system?

The V1K is made for three phase drive systems. If the drive is being fed by a single phase input power, the output will be three phase and the system will utilize a three phase motor. Because the output of the drive is three phase, the system will experience the same effects of dV/dt that a conventional three phase input power system will have. Yes, the V1K is well suited for this application to protect the motor from the effects of dV/dt.

Can I use the V1k on SCR based drives as well as diode front end drives?

The V1K is designed for use with modern PWM drives where dv/dt and the reflected wave phenomenon is a prevalent issue. Older series current source and SCR based drives incorporate early technology and switching speeds that do not produce as harmful a content of dv/dt and thus would not require this type of device for motor protection. Your drive manufacturer can respond to this question should you be using an earlier series of drive technology.

Do I size the V1K output filter to match the drive input current or the motor full load current rating?

Output devices are sized based on the load itself. The load determines the current that will be drawn through the filter. Merely size the filter based on the full load amp, (FLA) rating of the motor. We suggest you size the filter no more than 110% of the motor FLA to ensure a proper match between drive, load, and filter.

Do I still need to purchase a V1K filter for the output of my drive if I am using an inverter duty motor?

If you can add the low cost of the filter to your long lead drive application to preserve and extend the life of your drive system, it is typically very well spent dollars. Considering the cost of the motor, removal, re-installation, and the associated downtime and cost of frustration, the cost of the filter is minimal. Regardless if the motor’s insulation system can handle the spike voltage, it will be much less stressed and burdened with the filter in place. This will always help extend the service life of the system.

Does the V1K help prevent motor bearing currents?

A very positive effect of the V1K output filter is to greatly reduce the amount of common mode current on the line. Common mode current is the phenomenon which causes motor shaft bearing currents and the resulting motor bearing failures. By reducing this current, motor bearings can enjoy a longer service life. The V1K filter will not eliminate this current but will reduce the line content between 30 and 40%. This is notable and very much needed in motor and drive applications.

Does the V1K help with common mode current problems?

The main purpose of the V1K is to address and control the effects of dV/dt on the VFD output. Because of the circuit used, the V1K also reduces the content of common mode current on the line by 30-40%. This is especially useful in the prevention of motor shaft bearing currents which are known to cause premature motor bearing failures in adjustable frequency drive applications.

How does the V1K compare to the KLC output filter?

Essentially both are comparable dV/dt filters. Many of our customers have been asking us to reduce the required panel space for the filter and eliminate the “L” style base bracket used on the KLC. The V1K is an updated design responding to that request which focuses on mounting and installation convenience. They are very close in circuit design and thus both utilize the success of that filter on controlling dV/dt.

If I need a V1K above 750 amps, what do I do?

TCI has designed and developed the V1K to cover the vast majority of NEMA frame motor applications through 600 HP at 480 volts. Above that current level the V1K can be paralleled to achieve the performance of using a single device. For example if 1,500 amps is required, two 750 amp units can be wired in parallel and connected through a common power block on both the line and load side of the filter. While TCI does not provide this configuration, TCI Technical Support will assist you in these applications.

Is the V1K a 600 volt product?

The product has a 600 volt class of insulation and is safe for operation on 600 volt drive systems. Because this product focuses on the 480 volt product, it will operate safely on a 600 volt line but the level of dV/dt will be slightly higher than on a 480 volt system. Performance tests resulted in distortion voltage peaks of around 1,200 volts instead of the 1,000 volt limits on a 480 volt system. This level is still considerably less than the typical peak distortion voltage of up to 2,100 volts found on 600 volt systems and should greatly assist in extending the life of the electric motor.

Is the V1K connected the same way as the KLC output filter?

The V1K is connected in the same fashion as the KLC filter. It is a simple series connection between the drive and motor. Again, the filter is designed to be installed directly next to the drive and simply connected to the drive output terminals. Unlike some output filters that are installed at the motor end, the V1K is conveniently located along side the drive and is useful at protecting both the motor and lead cables.

Is the V1K the same as a sine wave filter?

The V1K is a drive output filter that addresses dV/dt. This filter is very effective in this cause and can protect standard and special service electric motors from the damaging affects of dV/dt. The V1K filter, however, does not return the drive output square wave to a sinusoidal waveform and thus is not referred to as a sine wave filter. TCI has designed a specific filter for those applications where extremely low distortion and near perfect sine wave performance is required. For those applications, please refer to the KMG MotorGuard sine wave filter.

What are the key components of the V1K output filter?

The V1K consists of two major components. The first part of the filter is a series line reactor which dampens the voltage distortion on the output of the VFD. The second component is a snubber circuit which effectively reduces the voltage distortion, dV/dt, to 1,000 volts per micro second on a typical 480 volt system. These two components are very effective at protecting the electric motor and the affects of dV/dt on the output side of the drive.

What is the lowest ambient temperature the V1k can be used in?

In most applications this is not a critical question. When an application does arise where the ambient temperature can be excessively low, we suggest the filter be exposed to a temperature of no lower than minus 15 degrees Fahrenheit unless special provisions are made. In some cases devices such as space heaters may be required when the device is not in operation. This follows true to most electronic equipment incorporating capacitors and other extreme-temperature sensitive components.

What is the maximum ambient temperature rating of the V1k?

Like most electrical equipment, all testing and rating data has been established having an ambient temperature of 40 degrees Celsius. Operating the filter in an ambient temperature above this should only be practiced when conferring with TCI Technical support to ensure the service life of the filter and the integrity of the filter performance is not in jeopardy.

Is there a difference between EMI and RFI?

The terms EMI and RFI are often used interchangeably. EMI is actually any frequency of electrical noise, whereas RFI is a specific subset of electrical noise on the EMI spectrum. There are two types of EMI. Conducted EMI is unwanted high frequencies that ride on the AC wave form. Radiated EMI is similar to an unwanted radio broadcast being emitted from the power lines. There are many pieces of equipment that can generate EMI, variable frequency drives included. In the case of variable frequency drives, the electrical noise produced is primarily contained in the switching edges of the PWM controller. As the technology of drives evolves, switching frequencies increase. These increases also increase the effective edge frequencies produced, thereby increasing the amount of electrical noise.

What is the difference between Common Mode noise and Differential Mode noise?

Common mode noise is the electrical noise on all power lines with respect to ground. Differential mode noise is the electrical noise on one line with respect to another line. When considering a filter for use in a variable speed drive application, it is important to note that common mode noise reduction is the most important factor. Variable frequency drives produce very little differential mode, or line to line, electrical noise due to the presence of DC bus capacitors.

Are there any guarantees with the V1K that my motor will not fail on my drive from dV/dt?

Power system dynamics are very difficult to quantitatively evaluate due to a variety of power system dynamics that can add to the harmful effects of dV/dt. Such components as line capacitance, parasitic capacitance, induced voltages and the like can intensify the voltage distortion on the line and contribute to the degradation of the motors insulation system. The V1K filter does an outstanding job of controlling these elements and bringing the distortion voltage down to a level that can be supported by the motors insulation system. Even standard electric motors can be used on drives with the V1K output filter.

Are there considerable line losses with the V1K?

Line losses from the V1K are not published because they vary greatly due to the system dynamics and such settings as drive carrier frequency. From independent testing done by a major drive manufacturer, the V1K was found to be 98% efficient in operation. From a line voltage drop consideration, the impedance of the filter is 1.5% at rated load. For example, a 21 amp V1K will have a line voltage drop of approximately 1.5% when applied to a 480 volt line at 21 amps. Because impedance is proportionate to the load, the line voltage drop will decrease as the percent of load decreases.

Can I place the V1K anywhere on the output side of the drive?

The V1K output filter is designed to be located directly next to the VFD. TCI recommends the filter be located within 10 feet of the drive to properly handle the voltage distortion, dV/dt, before it escalates on the line and causes damage to the motor and lead cables. If this is not possible due to the location or configuration of the drive system, we recommend our customers contact TCI Technical Support to discuss the application and ways to address this situation.

I have a harmonic limit requirement for my facility. What size HG7 filter do I use?

The best way to address specification and harmonic limits is to do a proper analysis of your power system to establish a base line value of the harmonics presently on the power system at the point of common coupling, (PCC). Once that value is found, a proper solution can be formulated for your facility. For specifications that state a specific value at the drive or filter terminals, TCI can typically provide an HG7 that will meet the limits of most power quality specifications. Most industry power quality people today rely on the committee studies and findings of IEEE. The guideline that IEEE established is their standard 519-1992. TCI complies with this standard on the HG7 drive-applied harmonic filter when the customer evaluates the harmonic content at the point of the drive or filter terminals. This standard has reached an industry wide level of acceptance, and most power quality Engineers will reference this standard and openly accept the performance of the TCI HG7 filter for drive applied applications. For additional information of IEEE-519 requirements and how the TCI HG7 filter complies, contact the TCI Technical Support staff or you local TCI Territory Manager.

What is included with the HG7 Power Monitor Option?

The Power Monitor package includes contactors and filter monitoring equipment. For units rated at 60 horsepower and below, the XM package utilizes indicator lights for filter operation and fuse failure. From 75 HP through 350 HP, the XM package uses the HG2™ Protection Monitor/Harmonic-Power Factor meter. The HG2™ Monitor Board displays operating information such as ITHD, VTHD, total filter amps, true power factor, and a series of fault and protection codes including over-current, over-voltage, and phase imbalance. It is also a programmable safety monitor, capable of bringing the filter off-line in a fault condition, or when the drive goes into a fault condition. For those applications that require the removal of capacitance for the start-up of stand-by generators, the contactors can remove the harmonic duty capacitors. Above 400 HP, the XM package includes a monitor board which has indicator lights to advise the mode of operation and when a fault should occur.

What is included with the HG7 Standard Package Option?

The Standard Package includes everything necessary for an application to meet IEEE 519 standards. From the highest quality harmonic grade capacitors on the market to the extraordinary reactors, this filter will meet the majority of application requirements found today. This cost effective product is available as either an open panel version or in a UL Type 1 enclosure. The open panel is perfect for inclusion in a MCC section or easy installation into industry standard enclosures. The UL Type 1 enclosed units maintain the same vertical profile as the open panel design. This design is perfect for applications where floor space is at a premium.

What kinds of problems are caused by harmonic distortion?

Harmonic distortion can cause poor power factor, transformer and distribution equipment overheating, random breaker tripping, or even sensitive equipment failure. Since harmonics affect the overall power distribution system, the power utility may even levy heavy fines when a facility is affecting the utilities’ ability to efficiently supply power to all of its customers.

When should I consider buying the “XM” Option over the standard HG7 filter?

The HG7 standard product is a high performance filter that will perform the function of mitigating excessive harmonics related to the drive system. The “XM” Option goes beyond that to allow additional control, alarm, and monitor features. The “XM” Option would be the desired version to specify if the customer is looking for alarm features should a filter fault occur or be able to turn off the filter circuit without shutting down the drive.

What’s the difference between NEMA and UL enclosures for KDR or KLR?

The National Electrical Manufacturers Association (NEMA) develops standards for the electrical manufacturing industry. Underwriters Laboratories Inc. (UL) is an independent, non-profit, product-safety testing and certification organization. Their ratings are based on similar application descriptions and expected performance. Installations require varying levels of standards and ratings to which TCI offers a range of products that meets those requirements.

Can I get design assistance if I purchase the HG7 Component Package “CP” filter?

The “CP” Option is designed for the very experienced panel builder and systems integrator. TCI can provide technical guidance but reserves the right of filter design to the experienced shop. Contact your TCI Territory or Regional Sales Manager for the required qualifications. If you are not familiar with your Territory or Regional Sales Manager, contact TCI Customer Service for a complete listing.

Can I order an HG7 with custom features not listed in the brochure?

TCI builds custom equipment for many customers and OEMs. It is in the best interest of everyone that a standard product be selected if possible. Often times, a small, seemingly simple modification can require added Engineering design time, drawings, and a list of special parts to be added. This results in added cost and lead time to acquire the equipment. TCI is sensitive to the needs of the application and suggests the solution product that is the most readily available and cost effective for the customer. If the standard product is not suited for the application or the customer requires special modifications, the TCI Technical Support staff can make suggestions and present ideas for the best solution available. TCI is interested in hearing the needs and requirements of our customers. Contact TCI at (414) 357-4480 or (800) TCI-8282 for more information on power quality and harmonic mitigation equipment.

Can I use the HG7 on a generator power source or is this strictly for use on utility power?

You can use the HG7 on generator power; however it is more critical to size the device properly. If the non-linear load represents a great portion of the total generator load and the drive is very lightly loaded, the filter capacitance may cause the generator to experience voltage regulation issues. Contact TCI Technical Support for a system evaluation. You may also contact the generator provider for their guidelines on the use of harmonic mitigation and capacitive equipment on their systems.

Can I use the HG7 on drive bypass applications?

Yes, an independent third party test was conducted to evaluate the use of the HG7 on bypass systems. The concern is to ensure the series inductor does not provide too excessive of a line voltage drop to prevent proper operation of the bypass control contactors. A 75 HP NEMA design A motor and drive package with a bypass option was tested. Extensive testing showed that the voltage drop across the 480/120 volt control power transformer being caused by the series reactor was approximately 10% at full load which was well within the contactor coils dropout rating. The bypass circuit worked very well and the results concluded the HG7 can be used with a standard drive/bypass configuration without any special system modifications.

Does the drive require special adjustments in order to use the HG7 filter?

TCI has studied the standard drive product offerings used in industry today. Standard, 6 pulse, PWM drives and standard NEMA design motors are compatible packages. The drives typically need no special adjustment when using the HG7 harmonic filter. If your drive application is utilizing unique drive components, contact your drive manufacturer’s technical support staff for clarification on limitations to harmonic mitigation equipment.

How can a harmonic filter improve my system power factor?

“Real” or True power is used to perform real work. Inductive loads require Real and Reactive power. Utilities provide apparent power. Apparent power is a geometric combination of Real and Reactive (or imaginary) power. Reactive power performs no work. However, the flow of reactive current, a component of reactive power, does consume energy as it passes through resistive elements of the power system, thus reducing overall system efficiency. This reactive power is used to generate magnetic fields within motors, transformers, and other magnetic devices. Reactive power, combined with harmonic currents, contribute to poor power factor in electrical systems. The capacitors inherent in the HG7 design supply the necessary reactive power so the utility doesn’t have to. The reduction in harmonic currents further improves the ratio of active power to apparent power. This overall improvement to true power factor assists in the efficient operation of facilities and the avoidance of possible fines due to poor power factor.

How can I find out if the filter will bring my power system into compliance with IEEE-519?

The best way for true power system evaluation is to have an actual power measurement taken at the facility. For the sake of an informal, computer assisted power system review, the Analyzer Program can be found on the TCI website. Contact TCI Technical Support for assistance on this and other thoughts on compliance with IEEE-519 standards.

Can reactors be considered “IGBT-protected” by passing a 4000V hipot test?

“IGBT protected” is a fabrication. A reactor applied at the output terminals of an IGBT based drive will see a maximum of 680V for a 480V system. A hipot test is a method of testing insulation integrity, and is a destructive test. In the real world, the only time that a reactor might see excessive voltages is when it is applied at the end of a long set of motor leads, which is an ill-advised and improper installation. This technique is used as a last ditch effort, in an attempt to batter the reactor with high overshoot voltages, instead of the motor. It will eventually lead to insulation destruction in the reactor, regardless of the reactor’s ability to pass a one or two-time 4000V hipot test back at the factory. In addition, this sacrificial lamb technique does nothing to protect the insulation of the motor lead wires, another susceptible system component. The appropriate solution to dv/dt longlead motor failures is the V1k output filter.

Is a DC bus choke the same thing as a line reactor?

No, they’re very different. The addition of DC bus chokes of significant inductance in 6 pulse AC drives will result in lower harmonic line currents as compared to drives without those chokes. However, the DC bus choke does not guarantee against the possibility of inverter shut down on DC bus over-voltage trips becuase in normal operation the magnetic structure is near saturation. (The inrush current that is delivered to the bus capacitor when a 2000V AC line voltage transient occurs easily saturates the DC choke, resulting in no circuit inductance.) The drive still trips, bus choke or no bus choke. Drives have a bus over-voltage trip mechanism to prevent against high bus voltages seen when the motor tries to regenerate, and to protect the diode bridge from high line-side voltages. Since the bus choke is not positioned in front of the diode bridge, it is unable to protect the drive from the former. A line reactor drops the high frequency transients that cause short DC bus over-voltage conditions, allowing the drive to continue operation through the transient period.

What is the advantage of having a UL Listed KDR or KLR Reactor?

The UL Listed mark provides a higher level of acceptability. KDR Optimized Drive Reactors that are UL Listed or UL Recognized meet the same safety standards but are viewed differently by Underwriters Laboratories. They consider UL Listed products as being complete end-products, versus components that will be used as part of a larger system. While a UL Recognized Reactor may adequately address a system’s needs, the field inspection may require UL Listed products in a given installation. UL Listed Reactors meet a broad range of installation requirements. UL Recognized products may require an addition to a user’s UL file, whereas UL Listed products may not.

What is the difference between KDR and KLR reactors that are UL Listed and UL Recognized?

The UL Listed Mark on a product is the manufacturer’s representation that samples of that complete product have been tested by UL to nationally recognized safety standards and found to be free from reasonably foreseeable risk of fire, electric shock and related hazards. UL’s Component Recognition Service covers the testing and evaluation of component products that are incomplete or restricted in performance capabilities. These components will later be used in complete end-products or systems Listed by UL.