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28.08.2015
XP Power announces the BCS series of industrial supplies aimed at a broad range of applications that use battery backup to maintain equipment operation during a mains failure. In the event of a power loss on the AC input, the battery charging output switches to an input from the battery source providing a power source to the load. XP Power announces the EPL225 series of high-efficiency, up to 95%, open-frame AC-DC power supplies approved for industrial, IT and medical applications. BACKUP ELECTRICAL GENERATORS - CONTENTS: Emergency electrical power generators for residential use - hookup basics.
We explain how to hook up or wire an electrical generator at a building, and we describe the transfer switch or isolation switch necessary to avoid dangerous electrical shock or fire hazards. We describe several methods for obtaining temporary or emergency electrical power from a car, RV or other 12-V or 24-V vehicle or system. At above left we illustrate an electrical transfer switch required for safe connection of a backup generator to a building's electrical system. A common exception to the practice of using only a single power source at an electrical sub panel is the provision for backup electrical generator power that feeds an electrical sub panel (or panel) that contains critical electrical circuits for a building (such as heat, refrigeration, communications equipment, medical equipment). In that case indeed there are two electrical power sources that in a sense "feed" an individual panel or sub panel but only one power source can be connected at a time. Watch out: Emergency backup electrical generators produce 120V and 240V which may cause fatal electrical shock if precautions are not followed. DO NOT under any circumstances connect your electrical generator to any circuit or receptacle that is receiving electrical power (home, office, etc) from any other sources as this is likely to result in a fire and damage all electrical systems and could also shock someone working on the system.
Other key safety warnings include the warning that the backup generator should not be operated indoors nor in an enclosed area - there are fire and also potentially fatal carbon monoxide hazard risks. Key in making that a safe installation is the use of an isolation switch that switches to provide an electrical power feed into the panel (or sub panel) from EITHER the electrical service entry from the utility company OR from the backup electrical generator. Our photo (left) shows a close-up view of the same isolation switch in our earlier picture.
An isolation switch allows only one electrical power source to be connected to feed a sub panel at a given time.
As an example of an isolation switch set-up for an auxiliary electrical power generator hookup at a private home, our photo (above left) shows the backup generator hookup that provides limited electrical power for critical building circuits during a power outage from the electrical utility.
Electrical Code" and acceptable for load transfer use on optional standby systems only.
We do not hook up multiple electrical power sources to a single electrical sub panel without using an isolation switch. In our photograph of an isolation switch hook-up (above left), the main electrical panel (1) is at left.
The sub panel shown at right (next to our client) was an addition to the original electrical system to support central air conditioning and is not part of this discussion.
O'Connor also warns that the generator must be located where exhaust fumes cannot enter the building (a carbon monoxide hazard), and about unsafe storage of fuel containers for the backup generator. The commercial backup electrical power generator shown at left includes its own fuel storage tank (at left in the photo). In the event of a power failure the system may start automatically and the necessary isolation switch may also be switched automatically to keep critical equipment in operation. A significant portion of the cost of installing a backup generator system will involve the provision for fuel storage, transfer switches, and the establishment & connection of the system to critical electrical circuits in the building. In a separate article found at ELECTRIC GENERATOR CAPACITY REQUIREMENTS [live link just below] we give backup generator size requirements tables for both backup electrical generators for home or commercial use and for smaller car or truck AC adapters. Continue reading at ELECTRIC GENERATOR CAPACITY REQUIREMENTS or select a topic from the More Reading links or topic ARTICLE INDEX shown below.
Now I am told that this panel cannot use the existing breakers as they are CH and it take BR. A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem or in this case to make recommendations for what you actually need. Eaton Corp., Cutler Hammer Products Adjustable Retrofit Kits, E-CH Load Centers and load center parts can be purchased through any E-CH distributor. But in my OPINION, if your panel is an older one, it would be safer not to re-use the old circuit breakers during a new panel replacement, even if they fit onto the new panel bus.
Before you replace your existing panel to expand the existing unit you first have a clear and correct plan for how you're going to hook up your generator to the existing house circuits.
Safe hookup of a generator requires an isolation switch that isolates the subset of circuits and original panel from the incoming electrical service mains when you are running the generator - it's got to be an exclusive OR - setup.
Finally, while I prefer to completely replace an older, obsolete, under-sized existing electrical panel, and while I will often upgrade the entire electrical service (incoming mains, main disconnect) at the same time (to be better able to meet contemporary electricity usage and the expanded number of circuits found in modern or upgraded homes) there are other options. Do you suggest I shop for the breakers, or just get a list of what I need and get them at the electrical parts distributor where I purchased the panel? If money's tight it may be worth comparing prices between the electrical supplier and Home Depot. Anon, if you mean can you use SEC grade or weight wire, sure, though depending on your generator size (output capacity) and distance from the building it may be overkill in wire size. If you mean can you connect the generator to the same lugs in the electric panel as the entering SEC wires, absolutely not. I considered installing the standard transfer panel when I got a backup generator, but my main panel was already way too crowded. The transfer switch is fed by a 60amp dual breaker in the main and the transfer switch has a 60amp dual breaker for supplying the sub panel I installed with 8 circuits in it. I used a couple of junction boxes to accomplish this since some of the wires were too short to reach the sub. Contact information for Reliance Controls who sells this product can be found in our reference listing just below.
As life and safety issues as well as permit and code issues are involved I'd expect one to use a licensed electrician who is familiar with aux generator and transfer switch wiring.
Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Recommended books on electrical inspection, electrical wiring, electrical problem diagnosis, and electrical repair can be found in the Electrical Books section of the InspectAPedia Bookstore. The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Dynamically designed by you based off your unique search, this customizable, casual and loose fitting t-shirt will quickly become one of your favorites. In low-power applications, vehicle, medicine, and household devices, where there is no ac supply or where reactive current and harmonics caused by a line commutation would be unreachable, it is accepted to employ forced commutatedconverters having a more complex circuitry and sometimes involving higher losses. Rectifiers differ by the shape of dc signal, ripples, and efficiency that depends on rms, average, and amplitude values of voltage, current, and power. The apparent rms power Ps, phase voltage Us, and current Is supply the rectifier directly, through chokes, or via a transformer. The ripple factor kr of the output waveform is usually determined by the rectified peak-to-peak ripple voltage swing Ur (see Fig. At power levels below a few kilowatts, for example in residential applications, the loads are supplied by a single-phase supply source. In the case of resistive load, Ud is always positive and ac line current (the same as the rectified current Id) has the half-sine shape and flows in phase with voltage. The two-thyristor single-phase full-wave rectifier (midpoint rectifier or M2) is shown in Fig. By adjusting the thyristor firing angle ? between 0 and ?, a user can run the machine in both directions, but the load current and the motor torque are unidirectional as Fig. To form a full-wave single-phase bridge rectifier (B2), four diodes or thyristors have to be interconnected, as Fig. The three-phase three-diode rectifier circuit (midpoint rectifier, M3) produces a purer direct voltage than the single-phase rectifier circuits do, thus wasting less power.
In the previous circuits, the polarity of the load voltage may be changed, but the direction of the load current remains constant.
Today, dual converters with anti-parallel thyristors are produced in large numbers in the form of very compact units covering a wide power range from a few kilowatts to tens of megawatts. The use of diode and thyristor rectifiers leads to the problems of electromagnetic compatibility (EMC).
Along with the growing pulse number of rectifiers, the frequencies of high order harmonics increase whereas their relative magnitude decreases.
The recent standardization in EMC specifies limits for harmonic distortion, which may be met with a diode and thyristor rectifier circuit, accomplished by passive filters on the mains side.
A variety of control strategies have been invented for this type of converters and their operational principles differ essentially. The main disadvantage of the two-diode midpoint rectifier is the requirement of a center-taped transformer.
A single-phase bridge rectifier uses the transformer and semiconductor devices more effectively; its current shape is more sinusoidal. Single-phase rectification results in two identical pulses per cycle in the rectified dc-side voltage, whereas three-phase rectification in three and more such pulses occurs. The three-phase bridge rectifiers are predominant because of their good technical properties: low ripple, high power factor, simple topology, and low price. It can be expected that this technique, which up to now is used rather seldom, will gain importance in the near future.


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They're as thick and strong as railroad tracks and could easily carry the equivalent of four TGVs, two Eurostars or 15 steam locomotives. Protection features of the BCS series include battery overload, reverse polarity, output overvoltage, and output short-circuit that prevent damage to the load, the external batteries and the power supply itself. We describe how to determine how much back up generator capacity or power in watts you'll require. Photo courtesy of Davies Hardware, Poughkeepsie, NY.[12] Similar models found at building suppliers range in capacity with common sizes in the 10,000 - 12,500 watt range for residential use. Some owners connect an extension cord to the generator's electrical supply receptacle and connect the other cord end to a tool or appliance - which may be safe.
Note that other safety precautions also apply - be sure to see the instructions provided with the generator. This avoids, for example, the hazard of shocking electrical workers who might be repairing the main electrical service. In general it is very dangerous to have multiple sources of power into a single panel or sub panel because of the possibility of back feeding and shocking someone who thinks power is off from a given source.
In the photo center is an isolation switch (2) that allows the homeowner to switch individual circuits from being powered either by the main electrical panel's service entry mains or by an electrical generator (located outdoors) that is connected to the isolation switch by a removable plug shown hanging on the wall (3). Rebuild and Floodproof, locating a backup generator onto upper building floors or the rooftop may not be enough to assure that the system can continue to operate during times of area flooding. A whole new larger electrical panel with new circuit breakers can often be obtained for economically from your local electrical or building suppliers. But watch out for third party "look alike" breakers - the panel manufacturer may object to their use, and indeed some substitute breakers made in China have performed poorly. The only draw back is that I had to physically remove the wiring for 8 circuits from the main panel and move them to the sub panel.
The interlinked circuit breakers keep the generator isolated from the utility at all times, even with the deadfront removed. The TCA is suitable for service entrance and may be used as a main panel for a single load or to feed a sub-panel. The text is intended as a reference guide to help building owners operate and maintain their home effectively. They convert ac to dc in a number of industrial, domestic, agricultural, and other applications.
This is due to simplicity of the circuits requiring a minimum number of active and passive components.
A special situation exists also with dc and ac loads, where the response of a line-commutated converter may be insufficient to cope with the stringent dynamic and energy efficiency demands and where an additional converter supplied by a dc link and operated with a high switching frequency is necessary. The current flows through the utility distribution and transmission lines, transformers and so on exciting the losses in their resistances. Commonly used simple half-wave single-phase rectifier circuits (M1) are represented in Fig. During the positive alternation of the ac sinusoidal wave, the anode of the diode VD is positive and the cathode is negative, the diode conducts since it is forward-biased.
The loads like motors have the properties of the resistive-inductive load; hence, Ud goes negative shortly, and ac line current (the same as Id) is out of phase with the voltage.
It is preferable to use a three-phase supply source, except at a fractional kilowatt, if such supply is available.
4, the anti-parallel connection of the two bridge rectifiers has been arranged to provide the four-quadrant operation. For the highest ratings, modular designs with air- and water-cooled heat sinks are available. Diodes and thyristors are the major contributors to power and current distortion problems, resulting in poor overall power factor, heating effects, device malfunction, and destruction of other equipment. Therefore, the trace of the input current becomes more sinusoidal, and the output current is smoothed better. Interest in active rectifiers has grown rapidly over the decade due to some of their important advantages, such as power regenerative capabilities, dc voltage adjustment, low harmonic distortion of input currents, and high power factor. 5, b, are built on transistors, which, unlike diodes and thyristors, are the full-controlled electronic devices with possible high-frequency performance. Although many control methods are known and implemented, there are two ways of circuit performance in terms of the active rectifier. Nevertheless, it has inadequate secondary current shape, very high ripple level, and very low power factor.
Therefore, three-phase rectifiers are superior in terms of minimizing distortion in line currents and ripple of the load voltage. We describe electrical grounding and other wiring & control or installation procedures backup electrical generators. So we don't hookup simultaneous live electrical power sources to a single electrical sub panel or main panel. You can see the receiving plug receptacle at the bottom center of the isolation switch (2). The fuel supply and isolation or transfer switches must also be located where they are protected from flood waters.
Indeed a common solution to wiring a backup generator is to feed a sub panel through an individual transfer switch, then wiring the critical building circuits out of the sub panel. The bottom of the bus has lugs that feed the house sub panel without any breakers between the disconnect and the house sub. One does not normally install a standby generator to power all of the circuits in a building nor a main panel nor a house sub panel that is really running all of the house circuits.
Rectifiers are used as stand-alone units feeding single and multiple dc loads and as input stages of ac systems because of their virtually unlimited output power and fine controllability. The systems built on diodes are called uncontrolled rectifiers, and those built on thyristors and transistors are known as controlled rectifiers because their dc output can be changed. Low-power devices operate usually from a single-phase supply while high-power rectifiers are mainly used in a three-phase configuration. The average rectified load power Pd, voltage Ud, and current Id are the pulsating dc signals with 1, 2, 3, or 6 pulses per supply period T. The peak inverse voltage UR and forward current IF of each rectifier device depends on the circuit type.
If the losses grow, possibly to the point of overloading, harmonic currents may cause resonance conditions in transmission lines.
When inductance aspires to infinity, the current waveform distorts and becomes almost rectangle. It produces a rectified rippled output voltage and current for each alternation of the ac input, as shows Fig. Thus, the rectifier is capable of operating in two quadrants of the current-voltage plane: the first quadrant is the rectifying mode of operation and the fourth quadrant supports the inverting mode of the operation.
VD1 charges C1 during the positive alternation of the supply voltage andVD2 charges C2 during the negative alternation. In the case of resistive-inductive load, the current continues through the diode or thyristor after the voltage has changed its sign. 3, a, the back-to-back connection of the two midpoint rectifiers has been produced to build a dual-controlled system. Such circuit is by far the most common industrial four-quadrant dc system and is used in many demanding applications where rapid control is required. It is remarkable that harmonics generated by rectifiers fall into the frequency spectrum up to about 3 kHz. On the contrary, when the firing angle of the rectifier grows, harmonic frequencies and their magnitude do not change, but the phase shift of harmonics increases relative to the supply voltage.
Further, in some EMC sensitive applications, the occurrence of harmonics in the rectifier, although filtered towards the supply mains, may disturb the operation of the whole system.
Mains would be connected here via inductors to the phase terminals Us while Ud represents the dc output. According to the first of them, the classical self-commutated bridge rectifier passes a positive current without affording any control function. When turned on, they connect the respective mains phase to the dc center point via the two diodes and the inductor, which makes the letter magnetize. Contrary to the Vienna rectifier, capacitors are located on the mains side of the converter and a dc voltage is adjusted between the positive and negative load terminals on the output side of the rectifier.
Low degree of the transformer use and low power factor are the main disadvantages of the three-phase three-diode rectifier. In advance of the meeting—in addition to the routine duties of reviewing design documentation submitted by the Chinese Domestic Agency and its suppliers—the review panel headed by chair Ivone Benfatto of ITER's Electrical Engineering Division faced the difficult challenge of finding flights to China in the context of a major Air France strike.
Our electrician tells me that our panel is full and to get a panel with at lest 24 circuits.
My question is can I remove the bus bars and route 4awgcu from the disconnect to the transfer switch and then the load from the switch to the breaker bus? To do so would require a larger standby generator than we usually find at residential properties.


Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Their speed of response is usually adequate to handle electromechanical transients occurring in motor drives and power suppliers.
In the table below, the main data of different non-controlled rectifier circuits with a resistive load are given. The power factor of a rectifier defines the ratio of the real average active power Pd to the apparent power Ps, which is the product of the rms voltage and the rms current, therefore ? is a phase displacement angle of current relative to voltage. The supply voltage waveform will also be distorted, adversely affecting other linear loads, if a significant portion of the load supplied by the consumer absorbs power by mean of distorted currents.
The resulting output voltage and current waveforms of the half-wave diode rectifier are shown in Fig. During the negative alternation of ac cycle, the anode becomes negative while the cathode is positive. During the performance of a bridge rectifier, two diodes are forward-biased in each alternation of the ac input voltage. 1, e, the phases L 1, L2, and L3 of the three-phase source are connected to the anodes of thyristors VS1, VS2, and VS3 via the transformer. For that reason, the thyristor does not close at the zero-voltage instant, but remains open.
The anodes of thyristors VS4, VS5, and VS6 are connected together at one point, while the cathodes of VS1, VS2, and VS3 are joined at the other point.
This is a four-quadrant dual rectifier because the negative current as well as the negative voltage may be produced here by the properly firing angle control (Fig. Usually, they incorporate additional features to enhance the safety of operation and to improve the control transients. They are conducted back into the power system producing a continuous distortion of the normal sinusoidal current waveform.
This effect causes the consumption of reactive power from the supply lines with the power factor decreasing. This single-phase full bridge can be used as a rectifier and an inverter; thus, it permits bi-directional energy transfer, which is useful for applications with energy recovery.
To pass a negative current for the motor braking, the transistors must be open in the switching mode. Furthermore, the zeroing phase angle between voltage and current traces avoids the occurrence of first harmonic reactive power. When turned off, the inductor demagnetizes into the dc load through the freewheeling diodes connected to the positive and negative load terminals, respectively. The circuit uses bi-directional switches consisting of diodes and transistors: IGBTs are depicted in this case. Nevertheless, sufficiently high quality of rectified voltage with small ripples is its main advantage.
Fortunately, all participants were able to arrive on time and the meeting was completed according to schedule. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. This is the reason why consumers prefer unity power factor that draws power at the minimum value of the rms current. The diode is reverse-biased by this voltage and practically no current will flow through the load.
When the positive alternation occurs, devices VS2 and VS3 are forward-biased, while VS1 and VS4 are reverse-biased. The load motor M is connected between the cathodes of the thyristors and the neutral of the transformer. By adjusting the thyristors firing angle, the negative voltage may be obtained, thus it is a two-quadrant converter again.
As a result, the demand for high quality power supply grows in the provision of unity power factor.
However, the circuit contains twice the amount of the switches compared to the passive rectifier.
As far as the second way is concerned, the transistor bridge rectifies a current and controls the rectified voltage, whilst the freewheeling diodes pass the negative current in the regeneration period without voltage control, as shows Fig. At the same rectified power, the rectifier input current has a significantly lower amplitude and rms value compared to a passive rectifier. It is advantageous that due to this division of the output voltage, the switches will need lower blocking voltage and thus better conduction characteristics can be used.
Rectifying and inverting modes of operation are possible here, similarly to the previous circuit. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The rectifier utilizes a center-tapped transformer that transfers alternating source voltage to the diode rectifier circuit.
As long as the converter cannot produce the negative output current, the motor control signals and braking modes should be limited. The conduction path follows from the ac source, through VS2, the load, then through VS3, and back to the source. When the phase L 1 is at its positive value, maximum conduction occurs through VS1 since it is forward-biased.
Therefore, the device connected to the most positive voltage will conduct in cathode group; the other two will be reverse-biased.
Here, while thyristors VS1, VS2, and VS3 pass the current, a rectifier operates in the first and fourth quadrants whereas since thyristors VS4, VS5, and VS6 pass the current, the second and the third quadrants are active. In the rectifying phase, the switches are off, whereas during the inverting phase a pair of switches is on.
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Such type of the converter is called a half-wave rectifier because the negative half cycles have been clipped off. The anodes of each device VS1 and VS2 are connected to the opposite ends of the transformer secondary winding. In the inverting mode, it is more convenient to express the firing angle in terms of the angle of advance from the end limit of the interval available for successful commutation than as a delay a from the beginning of the interval.
As well, the device connected to the most negative voltage will conduct in anode group; the other two in this group will be reverse-biased. Since the load voltage has mainly a positive half cycle, the load current is direct and discontinuous, meaning that it flows in only one direction and has breaks.
During the negative alternation, the current flows from the source through VS1, via the load, then through VS4, and back to the supply line.
Other thyristors operate in a similar manner, conducting during the positive ac input alternation and not conducting during the associated negative ac alternation. At least two devices are simultaneously in the open state here and at least one device from each group must conduct to facilitate the flow of the motor current.
Clearly, the gate adjustment of the switches is more complicated than this of thyristors because of the need in synchronization with the supply net and specific inductor; thus driving effort is somewhat higher. Interface requirements, key electrical and mechanical design, and Factory Acceptance Test (FAT) and Site Acceptance Test (SAT) procedures were carefully examined by the review panel members and experts. Thus, the rectifier is capable of operating in the first quadrant of the current-voltage plane, as Fig. The load motor M is connected between the common cathode point and the center-tap connector of the transformer. This causes the second alternation to appear across the load in the same direction as the first alternation.
The voltage ripple is low because the output voltage consists of six pulses per voltage period (Fig. The transformer, two diodes or thyristors, and the load form a complete path for the current.
As a result, both alternations of the input appear as the output across the load and pulsating current flows via the dc output. The timing diagrams and the current-voltage plane of the circuit are the same as for the full-wave rectifier.
This circuit does not require the neutral line of the three-phase source; therefore, a delta-connected source as well as a wye-connected one could be used. There were no critical chits and the review panel was confident that procurement can now advance to the next manufacturing review stage on schedule.
If the load possesses high inductance, the forward current continues on the negative anode voltage and the switching-off of the device is delayed. Since the previously opened devices are not closed after the opening the next devices, it is possible that three or even four devices are open during the commutation process. This means that there is more than one open diode in the cathode or anode group and the current re-switches from one phase to another.




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