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98-510: The prototype SL2000 was first exhibited at photokina '76, featuring both aperture- and shutter-priority autoexposure modes along with a top speed of 1 ⁄ 2000  sec. However, when it was released in February 1981 for Germany and selected other European countries, the shutter-priority mode had been dropped and the top speed reduced to 1 ⁄ 1000  sec. Rollei's bankruptcy later that year halted production temporarily. The SL3003

196-512: A " memory effect " if they are discharged and recharged to the same state of charge hundreds of times. The apparent symptom is that the battery "remembers" the point in its discharge cycle where recharging began and during subsequent use suffers a sudden drop in voltage at that point, as if the battery had been discharged. The capacity of the battery is not actually reduced substantially. Some electronics designed to be powered by Ni–Cd batteries are able to withstand this reduced voltage long enough for

294-419: A 4C or 6C charge rate, but this is very uncommon. It also greatly increases the risk of the cells overheating and venting due to an internal over-pressure condition: the cell's rate of temperature rise is governed by its internal resistance and the square of the charging rate. At a 4C rate, the amount of heat generated in the cell is sixteen times higher than the heat at the 1C rate. The downside to faster charging

392-496: A UPS should be selected not only by capacity but also by the quality of power that is required by the equipment that is being supplied. The three general categories of modern UPS systems are on-line , line-interactive and standby : Most UPS below one kilo volt-ampere (1 kVA) are of the line-interactive or standby variety which are usually less expensive. For large power units, dynamic uninterruptible power supplies (DUPS) are sometimes used. A synchronous motor/alternator

490-404: A battery is constant current charged at 1 CA rate until all the cells have reached at least 1.55   V. Another charge cycle follows at 0.1 CA rate, again until all cells have reached 1.55   V. The charge is finished with an equalizing or top-up charge, typically for not less than 4 hours at 0.1 CA rate. The purpose of the over-charge is to expel as much (if not all) of the gases collected on

588-449: A battery-based UPS, flywheel-based UPS systems typically provide 10 to 20 seconds of protection before the flywheel has slowed and power output stops. It is traditionally used in conjunction with standby generators, providing backup power only for the brief period of time the engine needs to start running and stabilize its output. The rotary UPS is generally reserved for applications needing more than 10,000 W of protection, to justify

686-474: A common consumer device, supplying 500 W or less. The online UPS may be necessary when the power environment is "noisy", when utility power sags, outages and other anomalies are frequent, when protection of sensitive IT equipment loads is required, or when operation from an extended-run backup generator is necessary. The basic technology of the online UPS is the same as in a standby or line-interactive UPS. However, it typically costs much more, due to it having

784-401: A cool, dry environment. Sealed Ni–Cd cells consist of a pressure vessel that is supposed to contain any generation of oxygen and hydrogen gases until they can recombine back to water. Such generation typically occurs during rapid charge and discharge, and exceedingly at overcharge condition. If the pressure exceeds the limit of the safety valve, water in the form of gas is lost. Since the vessel

882-510: A current equal to one tenth the ampere-hour rating (C/10) for 14–16 hours; that is, a 100 mAh battery takes 10 mA for 14 hours, for a total of 140 mAh to charge at this rate. At the rapid-charge rate, done at 100% of the rated capacity of the battery in 1 hour (1C), the battery holds roughly 80% of the charge, so a 100 mAh battery takes 125 mAh to charge (that is, approximately 1 hour and fifteen minutes). Some specialized batteries can be charged in as little as 10–15 minutes at

980-596: A fair capacity but their significant advantage is the ability to deliver practically their full rated capacity at high discharge rates (discharging in one hour or less). However, the materials are more costly than that of the lead–acid battery , and the cells have high self-discharge rates. Sealed Ni–Cd cells were at one time widely used in portable power tools, photography equipment, flashlights , emergency lighting, hobby RC , and portable electronic devices. The superior capacity of nickel–metal hydride batteries , and recent lower cost, has largely supplanted Ni–Cd use. Further,

1078-422: A fan system or an air conditioning system. A solar inverter , or PV inverter , or solar converter , converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequency alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. It is a critical BOS –component in a photovoltaic system , allowing

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1176-441: A favourable choice for remote-controlled electric model airplanes, boats, and cars, as well as cordless power tools and camera flash units. Advances in battery-manufacturing technologies throughout the second half of the twentieth century have made batteries increasingly cheaper to produce. Battery-powered devices in general have increased in popularity. As of 2000, about 1.5 billion Ni–Cd batteries were produced annually. Up until

1274-573: A floating battery electrical system the regulator voltage is set to charge the battery at constant potential charge (typically 14 or 28   V). If this voltage is set too high it will result in rapid electrolyte loss. A failed charge regulator may allow the charge voltage to rise well above this value, causing a massive overcharge with boiling over of the electrolyte. Most of the uses described below are shown for historical purposes, as sealed (portable) Ni-Cd batteries have progressively been displaced by higher performance Li-ion cells, and their placing on

1372-533: A generator is the voltage distortion created by the UPS. The input of a double-conversion UPS is essentially a big rectifier. The current drawn by the UPS is non-sinusoidal. This can cause the voltage from the AC mains or a generator to also become non-sinusoidal. The voltage distortion then can cause problems in all electrical equipment connected to that power source, including the UPS itself. It will also cause more power to be lost in

1470-427: A high rate or recharged at a higher than nominal rate. This also means the electrolyte lost during venting must be periodically replaced through routine maintenance. Depending on the charge–discharge cycles and type of battery this can mean a maintenance period of anything from a few months to a year. Vented-cell voltage rises rapidly at the end of charge allowing for very simple charger circuitry to be used. Typically

1568-503: A hundred amps or so from specially constructed Ni–Cd batteries, which are used to drive main motors. 5–6 minutes of model operation is easily achievable from quite small batteries, so a reasonably high power-to-weight figure is achieved, comparable to internal combustion motors, though of lesser duration. In this, however, they have been largely superseded by lithium polymer (LiPo) and lithium iron phosphate (LiFe) batteries, which can provide even higher energy densities. Ni–Cd cells have

1666-475: A much greater current AC-to-DC battery-charger/rectifier, and with the rectifier and inverter designed to run continuously with improved cooling systems. It is called a double-conversion UPS due to the rectifier directly driving the inverter, even when powered from normal AC current. Online UPS typically has a static transfer switch (STS) for increasing reliability. These hybrid rotary UPS designs do not have official designations, although one name used by UTL

1764-555: A nominal cell potential of 1.2 volts (V). This is lower than the 1.5 V of alkaline and zinc–carbon primary cells, and consequently they are not appropriate as a replacement in all applications. However, the 1.5 V of a primary alkaline cell refers to its initial, rather than average, voltage. Unlike alkaline and zinc–carbon primary cells, a Ni–Cd cell's terminal voltage only changes a little as it discharges. Because many electronic devices are designed to work with primary cells that may discharge to as low as 0.90 to 1.0 V per cell,

1862-496: A porous nickel-plated electrode and fifteen years later work began on a sealed nickel–cadmium battery. The first production in the United States began in 1946. Up to this point, the batteries were "pocket type," constructed of nickel-plated steel pockets containing nickel and cadmium active materials. Around the middle of the twentieth century, sintered -plate Ni–Cd batteries became increasingly popular. Fusing nickel powder at

1960-414: A purely electronic UPS, and are better able to provide inrush current for inductive loads such as motor startup or compressor loads, as well as medical MRI and cath lab equipment. It is also able to tolerate short-circuit conditions up to 17 times larger than an electronic UPS, permitting one device to blow a fuse and fail while other devices still continue to be powered from the rotary UPS. Its life cycle

2058-400: A sealing plate equipped with a self-sealing safety valve . The positive and negative electrode plates, isolated from each other by the separator, are rolled in a spiral shape inside the case. This is known as the jelly-roll design and allows a Ni–Cd cell to deliver a much higher maximum current than an equivalent size alkaline cell. Alkaline cells have a bobbin construction where the cell casing

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2156-490: A separate NiCd pack is available. Film must be rewound back into the cartridge manually. Manually selectable shutter speeds range from 16 to 1 ⁄ 1000  sec., with a "B"ulb mode. The vertically-traveling focal plane shutter has a maximum flash synchronization speed of 1 ⁄ 125  sec. In aperture-priority automatic exposure mode, the camera can select a top speed of 1 ⁄ 2000  sec. under certain conditions. An accessory Sportsfinder Prism

2254-418: A short-term energy source instead of batteries to allow time for external, electrically coupled gensets to start and be brought online. Case Nos. 2 and 3 can use batteries or a free-standing electrically coupled flywheel as the short-term energy source. Smaller UPS systems come in several different forms and sizes. However, the two most common forms are tower and rack-mount. Tower models stand upright on

2352-530: A single computer (around 200 volt-ampere rating) to large units powering entire data centers or buildings. The primary role of any UPS is to provide short-term power when the input power source fails. However, most UPS units are also capable in varying degrees of correcting common utility power problems: Some manufacturers of UPS units categorize their products in accordance with the number of power-related problems they address. A UPS unit may also introduce problems with electric power quality . To prevent this,

2450-425: A temperature well below its melting point using high pressures creates sintered plates. The plates thus formed are highly porous, about 80 percent by volume. Positive and negative plates are produced by soaking the nickel plates in nickel- and cadmium-active materials, respectively. Sintered plates are usually much thinner than the pocket type, resulting in greater surface area per volume and higher currents. In general,

2548-508: A terminal voltage during discharge of around 1.2 volts which decreases little until nearly the end of discharge. The maximum electromotive force offered by a Ni–Cd cell is 1.3   V. Ni–Cd batteries are made in a wide range of sizes and capacities, from portable sealed types interchangeable with carbon–zinc dry cells, to large ventilated cells used for standby power and motive power. Compared with other types of rechargeable cells they offer good cycle life and performance at low temperatures with

2646-415: A traditional auxiliary / emergency power system or standby generator in that it will provide near-instantaneous protection from input power interruptions by switching to energy stored in battery packs , supercapacitors or flywheels . The on-battery run-times of most UPSs are relatively short (only a few minutes) but sufficient to "buy time" for initiating a standby power source or properly shutting down

2744-808: A vent or low pressure release valve that releases any generated oxygen and hydrogen gases when overcharged or discharged rapidly. Since the battery is not a pressure vessel , it is safer, weighs less, and has a simpler and more economical structure. This also means the battery is not normally damaged by excessive rates of overcharge, discharge or even negative charge. They are used in aviation, rail and mass transit, backup power for telecoms, engine starting for backup turbines etc. Using vented-cell Ni–Cd batteries results in reduction in size, weight and maintenance requirements over other types of batteries. Vented-cell Ni–Cd batteries have long lives (up to 20 years or more, depending on type) and operate at extreme temperatures (from −40 to 70 °C). A steel battery box contains

2842-436: Is "double conversion on demand". This style of UPS is targeted towards high-efficiency applications while still maintaining the features and protection level offered by double conversion. A hybrid (double conversion on demand) UPS operates as an off-line/standby UPS when power conditions are within a certain preset window. This allows the UPS to achieve very high efficiency ratings. When the power conditions fluctuate outside of

2940-603: Is a toxic heavy metal and therefore requires special care during battery disposal. In the United States , the expected battery recycling cost (to be used for proper disposal at the end of the service lifetime) is rolled into the battery purchase price. Under the so-called "batteries directive" ( 2006/66/EC ), the sale of consumer Ni–Cd batteries has now been banned within the European Union except for medical use; alarm systems; emergency lighting; and portable power tools. This last category has been banned effective 2016. Under

3038-437: Is a type of rechargeable battery using nickel oxide hydroxide and metallic cadmium as electrodes . The abbreviation Ni–Cd is derived from the chemical symbols of nickel (Ni) and cadmium (Cd): the abbreviation NiCad is a registered trademark of SAFT Corporation , although this brand name is commonly used to describe all Ni–Cd batteries. Wet-cell nickel–cadmium batteries were invented in 1899. A Ni–Cd battery has

Rolleiflex SL2000F - Misplaced Pages Continue

3136-467: Is also referred to as 1 + 1 or 2 N redundancy. If the budget does not allow for two identical UPS units then it is common practice to plug one power supply into mains power and the other into the UPS. When a UPS system is placed outdoors, it should have some specific features that guarantee that it can tolerate weather without any effects on performance. Factors such as temperature, humidity , rain, and snow among others should be considered by

3234-419: Is connected on the mains via a choke . Energy is stored in a flywheel . When the mains power fails, an eddy-current regulation maintains the power on the load as long as the flywheel's energy is not exhausted. DUPS are sometimes combined or integrated with a diesel generator that is turned on after a brief delay, forming a diesel rotary uninterruptible power supply (DRUPS). The offline/standby UPS offers only

3332-411: Is designed to contain an exact amount of electrolyte this loss will rapidly affect the capacity of the cell and its ability to receive and deliver current. To detect all conditions of overcharge demands great sophistication from the charging circuit and a cheap charger will eventually damage even the best quality cells. A fully charged Ni–Cd cell contains: Ni–Cd batteries usually have a metal case with

3430-431: Is filled with electrolyte and contains a graphite rod which acts as the positive electrode. As a relatively small area of the electrode is in contact with the electrolyte (as opposed to the jelly-roll design), the internal resistance for an equivalent sized alkaline cell is higher which limits the maximum current that can be delivered. The chemical reactions at the cadmium electrode during discharge are: The reactions at

3528-415: Is finding use in some data center applications and allows for small power conductors, but is subject to the more complex electrical code rules for safe containment of high voltages. For lower power devices that run on 5 V, some portable battery banks can work as a UPS. A rotary UPS uses the inertia of a high-mass spinning flywheel ( flywheel energy storage ) to provide short-term ride-through in

3626-494: Is important, Ni–Cd batteries are now at a disadvantage compared with nickel–metal hydride and lithium-ion batteries. However, the Ni–Cd battery is still very useful in applications requiring very high discharge rates because it can endure such discharge with no damage or loss of capacity. When compared to other forms of rechargeable battery, the Ni–Cd battery has a number of distinct advantages: The primary trade-off with Ni–Cd batteries

3724-458: Is mostly used in automotive and heavy-duty industrial applications. For portable applications, the number of cells is normally below 18 cells (24 V). Industrial-sized flooded batteries are available with capacities ranging from 12.5 Ah up to several hundred Ah. Recently, nickel–metal hydride and lithium-ion batteries have become commercially available and cheaper, the former type now rivaling Ni–Cd batteries in cost. Where energy density

3822-645: Is the addition of lithium hydroxide to the potassium hydroxide electrolyte. This was believed to prolong the service life by making the cell more resistant to electrical abuse. The Ni–Cd battery in its modern form is extremely resistant to electrical abuse anyway, so this practice has been discontinued. Larger flooded cells are used for aircraft starting batteries , standby power and marginally in electric vehicles , Vented-cell ( wet cell , flooded cell ) Ni–Cd batteries are used when large capacities and high discharge rates are required. Unlike typical Ni–Cd cells, which are sealed (see next section), vented cells have

3920-422: Is the higher risk of overcharging , which can damage the battery. and the increased temperatures the cell has to endure (which potentially shortens its life). The safe temperature range when in use is between −20 °C and 45 °C. During charging, the battery temperature typically stays low, around the same as the ambient temperature (the charging reaction absorbs energy), but as the battery nears full charge

4018-479: Is their higher cost and the use of cadmium. This heavy metal is an environmental hazard, and is highly toxic to all higher forms of life. They are also more costly than lead–acid batteries because nickel and cadmium cost more. One of the biggest disadvantages is that the battery exhibits a very marked negative temperature coefficient. This means that as the cell temperature rises, the internal resistance falls. This can pose considerable charging problems, particularly with

Rolleiflex SL2000F - Misplaced Pages Continue

4116-594: Is usually far greater than a purely electronic UPS, up to 30 years or more. But they do require periodic downtime for mechanical maintenance, such as ball bearing replacement. In larger systems, redundancy of the system ensures the availability of processes during this maintenance. Battery-based designs do not require downtime if the batteries can be hot-swapped , which is usually the case for larger units. Newer rotary units use technologies such as magnetic bearings and air-evacuated enclosures to increase standby efficiency and reduce maintenance to very low levels. Typically,

4214-473: The EU market has, for the most part, been prohibited since 2006 by the 2006/66/EC EU Batteries Directive. Sealed Ni–Cd cells were used individually, or assembled into battery packs containing two or more cells. Small cells are used for portable electronics and toys (such as solar garden lights), often using cells manufactured in the same sizes as primary cells . When Ni–Cd batteries are substituted for primary cells,

4312-448: The Earth over a period of several years. After this time, it was found that the capacities of the batteries had declined significantly, but were still fit for use. It is unlikely that this precise repetitive charging (for example, 1,000 charges/discharges with less than 2% variability) could ever be reproduced by individuals using electrical goods. The original paper describing the memory effect

4410-538: The NiCad batteries have substantially lower self-discharge, on the order of 1% or 2% per month. It is possible to perform a trickle charge at current levels just high enough to offset this discharge rate; to keep a battery fully charged. However, if the battery is going to be stored unused for a long period of time, it should be discharged down to at most 40% of capacity (some manufacturers recommend fully discharging and even short-circuiting once fully discharged ), and stored in

4508-411: The UPS will use more current than normal, so it may need a higher current circuit than a normal device. For example, to power a 1000 W device at 120 V, the UPS will draw 8.33 A. If a brownout occurs and the voltage drops to 100 V, the UPS will draw 10 A to compensate. This also works in reverse, so that in an overvoltage condition, the UPS will need less current. In an online UPS,

4606-689: The UPS, but may be corrected by reducing the load levels or adding other linear type loads. A UPS designed for powering DC equipment is very similar to an online UPS, except that it does not need an output inverter. Also, if the UPS's battery voltage is matched with the voltage the device needs, the device's power supply will not be needed either. Since one or more power conversion steps are eliminated, this increases efficiency and run time. Many systems used in telecommunications use an extra-low voltage " common battery " 48 V DC power, because it has less restrictive safety regulations, such as being installed in conduit and junction boxes. DC has typically been

4704-483: The amount of time it takes the standby UPS to detect the lost utility voltage. The UPS will be designed to power certain equipment, such as a personal computer, without any objectionable dip or brownout to that device. The line-interactive UPS is similar in operation to a standby UPS but with the addition of a multi-tap variable-voltage autotransformer . This is a special type of transformer that can add or subtract powered coils of wire, thereby increasing or decreasing

4802-479: The autotransformer. Depending on the design, changing the autotransformer tap can cause a very brief output power disruption, which may cause UPSs equipped with a power-loss alarm to "chirp" for a moment. This has become popular even in the cheapest UPSes because it takes advantage of components already included. The main 50/60 Hz transformer used to convert between line voltage and battery voltage needs to provide two slightly different turns ratios: One to convert

4900-426: The batteries are always connected to the inverter, so that no power transfer switches are necessary. When power loss occurs, the rectifier simply drops out of the circuit and the batteries keep the power steady and unchanged. When power is restored, the rectifier resumes carrying most of the load and begins charging the batteries, though the charging current may be limited to prevent the high-power rectifier from damaging

4998-472: The batteries. The main advantage of an online UPS is its ability to provide an "electrical firewall" between the incoming utility power and sensitive electronic equipment. The online UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations. Although it was at one time reserved for very large installations of 10 kW or more, advances in technology have now permitted it to be available as

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5096-404: The battery output voltage (typically a multiple of 12 V) to line voltage, and a second one to convert the line voltage to a slightly higher battery charging voltage (such as a multiple of 14 V). The difference between the two voltages is because charging a battery requires a delta voltage (up to 13–14 V for charging a 12 V battery). Furthermore, it is easier to do the switching on

5194-592: The cadmium in varying quantities, but found the iron formulations to be wanting. Jungner's work was largely unknown in the United States. Thomas Edison patented a nickel– or cobalt–cadmium battery in 1902, and adapted the battery design when he introduced the nickel–iron battery to the US two years after Jungner had built one. In 1906, Jungner established a factory close to Oskarshamn, Sweden, to produce flooded design Ni–Cd batteries. In 1932, active materials were deposited inside

5292-430: The cell was manufactured. The charge rate is measured based on the percentage of the amp-hour capacity the battery is fed as a steady current over the duration of the charge. Regardless of the charge speed, more energy must be supplied to the battery than its actual capacity, to account for energy loss during charging, with faster charges being more efficient. For example, an "overnight" charge, might consist of supplying

5390-476: The cells connected in series to gain the desired voltage (1.2 V per cell nominal). Cells are usually made of a light and durable polyamide ( nylon ), with multiple nickel–cadmium plates welded together for each electrode inside. A separator or liner made of silicone rubber acts as an insulator and a gas barrier between the electrodes. Cells are flooded with an electrolyte of 30% aqueous solution of potassium hydroxide ( KOH ). The specific gravity of

5488-512: The dominant power source for telecommunications, and AC has typically been the dominant source for computers and servers. There has been much experimentation with 48 V DC power for computer servers, in the hope of reducing the likelihood of failure and the cost of equipment. However, to supply the same amount of power, the current would be higher than an equivalent 115 V or 230 V circuit; greater current requires larger conductors or more energy lost as heat. High voltage DC (380 V)

5586-494: The electrodes, hydrogen on the negative and oxygen on the positive, and some of these gases recombine to form water which in turn will raise the electrolyte level to its highest level after which it is safe to adjust the electrolyte levels. During the over-charge or top-up charge, the cell voltages will go beyond 1.6 V and then slowly start to drop. No cell should rise above 1.71   V (dry cell) or drop below 1.55   V (gas barrier broken). In an aircraft installation with

5684-420: The electrolyte does not indicate if the battery is discharged or fully charged but changes mainly with evaporation of water. The top of the cell contains a space for excess electrolyte and a pressure release vent. Large nickel-plated copper studs and thick interconnecting links assure minimum equivalent series resistance for the battery. The venting of gases means that the battery is either being discharged at

5782-399: The entire server by itself. Redundancy is further enhanced by plugging each power supply into a different circuit (i.e. to a different circuit breaker ). Redundant protection can be extended further yet by connecting each power supply to its own UPS. This provides double protection from both a power supply failure and a UPS failure, so that continued operation is assured. This configuration

5880-463: The environmental impact of the disposal of the toxic metal cadmium has contributed considerably to the reduction in their use. Within the European Union, Ni–Cd batteries can now only be supplied for replacement purposes or for certain types of new equipment such as medical devices. Larger ventilated wet cell Ni–Cd batteries are used in emergency lighting, standby power, and uninterruptible power supplies and other applications. The first Ni–Cd battery

5978-402: The event of power loss. The flywheel also acts as a buffer against power spikes and sags, since such short-term power events are not able to appreciably affect the rotational speed of the high-mass flywheel. It is also one of the oldest designs, predating vacuum tubes and integrated circuits. It can be considered to be on line since it spins continuously under normal conditions. However, unlike

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6076-416: The expense and benefit from the advantages rotary UPS systems bring. A larger flywheel or multiple flywheels operating in parallel will increase the reserve running time or capacity. Because the flywheels are a mechanical power source, it is not necessary to use an electric motor or generator as an intermediary between it and a diesel engine designed to provide emergency power. By using a transmission gearbox,

6174-500: The greater amount of reactive material surface area in a battery, the lower its internal resistance . Since the 2000s, all consumer Ni–Cd batteries use the jelly-roll configuration. The maximum discharge rate for a Ni–Cd battery varies by size. For a common AA-size cell, the maximum discharge rate is approximately 1.8 amperes; for a D size battery the discharge rate can be as high as 3.5 amperes. Model-aircraft or -boat builders often take much larger currents of up to

6272-433: The ground or horizontally as would be found in a rack. In large business environments where reliability is of great importance, a single huge UPS can also be a single point of failure that can disrupt many other systems. To provide greater reliability, multiple smaller UPS modules and batteries can be integrated together to provide redundant power protection equivalent to one very large UPS. " N  + 1" means that if

6370-405: The ground or on a desk or shelf, and are typically used in network workstations or desktop computer applications. Rack-mount models can be mounted in standard 19-inch rack enclosures and can require anywhere from 1U to 12U ( rack units ). They are typically used in server and networking applications. Some devices feature user interfaces that rotate 90°, allowing the devices to be mounted vertically on

6468-456: The high-mass flywheel is used in conjunction with a motor-generator system. These units can be configured as: In case No. 3, the motor generator can be synchronous/synchronous or induction/synchronous. The motor side of the unit in case Nos. 2 and 3 can be driven directly by an AC power source (typically when in inverter bypass), a 6-step double-conversion motor drive, or a 6-pulse inverter. Case No. 1 uses an integrated flywheel as

6566-455: The line-voltage side of the transformer because of the lower currents on that side. To gain the buck/boost feature, all that is required is two separate switches so that the AC input can be connected to one of the two primary taps, while the load is connected to the other, thus using the main transformer's primary windings as an autotransformer. The battery can still be charged while "bucking" an overvoltage, but while "boosting" an undervoltage,

6664-417: The load can be supplied by N modules, the installation will contain N  + 1 modules. In this way, failure of one module will not impact system operation. Many computer servers offer the option of redundant power supplies , so that in the event of one power supply failing, one or more other power supplies are able to power the load. This is a critical point – each power supply must be able to power

6762-436: The load. This once was the dominant type of UPS and is limited to around the 150 kVA range. These units are still mainly used in some industrial settings (oil and gas, petrochemical, chemical, utility, and heavy industry markets) due to the robust nature of the UPS. Many ferroresonant UPSs utilizing controlled ferro technology may interact with power-factor-correcting equipment. This will result in fluctuating output voltage of

6860-485: The lower terminal voltage and smaller ampere-hour capacity may reduce performance as compared to primary cells. Miniature button cells are sometimes used in photographic equipment, hand-held lamps (flashlight or torch), computer-memory standby, toys, and novelties. Specialty Ni–Cd batteries were used in cordless and wireless telephones, emergency lighting, and other applications. With a relatively low internal resistance , they can supply high surge currents . This makes them

6958-451: The magnetic field and the output voltage of the transformer. This may also be performed by a buck–boost transformer which is distinct from an autotransformer, since the former may be wired to provide galvanic isolation . This type of UPS is able to tolerate continuous undervoltage brownouts and overvoltage surges without consuming the limited reserve battery power. It instead compensates by automatically selecting different power taps on

7056-422: The manufacturer when designing an outdoor UPS system. Operating temperature ranges for outdoor UPS systems could be around −40 °C to +55  °C . Outdoor UPS systems can either be pole, ground (pedestal), or host mounted. Outdoor environment could mean extreme cold, in which case the outdoor UPS system should include a battery heater mat, or extreme heat, in which case the outdoor UPS system should include

7154-425: The memory effect is the so-called voltage depression or lazy battery effect . This results from repeated overcharging; the symptom is that the battery appears to be fully charged but discharges quickly after only a brief period of operation. In rare cases, much of the lost capacity can be recovered by a few deep-discharge cycles, a function often provided by automatic battery chargers. However, this process may reduce

7252-580: The mid-1990s, Ni–Cd batteries had an overwhelming majority of the market share for rechargeable batteries in home electronics. At one point, Ni–Cd batteries accounted for 8% of all portable secondary (rechargeable) battery sales in the EU, and in the UK for 9.2% (disposal) and in Switzerland for 1.3% of all portable battery sales. In the EU the 2006 Battery Directive restricted sales of Ni–Cd batteries to consumers for portable devices. Ni–Cd cells are available in

7350-494: The most basic features, providing surge protection and battery backup. The protected equipment is normally connected directly to incoming utility power. When the incoming voltage falls below or rises above a predetermined level the UPS turns on its internal DC-AC inverter circuitry, which is powered from an internal storage battery. The UPS then mechanically switches the connected equipment onto its DC-AC inverter output. The switch-over time can be as long as 25 milliseconds depending on

7448-408: The negative. It was not until later that pure cadmium metal and nickel hydroxide were used. Until about 1960, the chemical reaction was not completely understood. There were several speculations as to the reaction products. The debate was finally resolved by infrared spectroscopy , which revealed cadmium hydroxide and nickel hydroxide. Another historically important variation on the basic Ni–Cd cell

7546-439: The nickel oxide electrode are: The net reaction during discharge is During recharge, the reactions go from right to left. The alkaline electrolyte (commonly KOH) is not consumed in this reaction and therefore its specific gravity , unlike in lead–acid batteries, is not a guide to its state of charge. When Jungner built the first Ni–Cd batteries, he used nickel oxide in the positive electrode, and iron and cadmium materials in

7644-413: The output resembles a square wave rich in harmonics. These harmonics can cause interference with other electronic devices including radio communication and some devices (e.g. inductive loads such as AC motors) may perform with reduced efficiency or not at all. More sophisticated (and expensive) UPS units can produce nearly pure sinusoidal AC power. A problem in the combination of a double-conversion UPS and

7742-414: The output. This transformer is designed to hold energy long enough to cover the time between switching from line power to battery power and effectively eliminates the transfer time. Many ferroresonant UPSs are 82–88% efficient (AC/DC-AC) and offer excellent isolation. The transformer has three windings, one for ordinary mains power, the second for rectified battery power, and the third for output AC power to

7840-411: The over-current cut-out operated or the battery destroyed itself. This is the principal factor that prevents its use as engine-starting batteries. Today with alternator-based charging systems with solid-state regulators, the construction of a suitable charging system would be relatively simple, but the car manufacturers are reluctant to abandon tried-and-tested technology. Ni–Cd batteries may suffer from

7938-491: The photographer to set the film speed and roll length using two dials; film is carried in an interchangeable cassette insert which can be removed through the bottom of the magazine independently of the magazine itself. In 1983, Rollei introduced a 250-exposure magazine back. Also that year, a Polaroid film back was released. A 750-exposure magazine back was introduced in 1988. Nickel%E2%80%93cadmium battery The nickel–cadmium battery ( Ni–Cd battery or NiCad battery )

8036-401: The predefined windows, the UPS switches to online/double-conversion operation. In double-conversion mode the UPS can adjust for voltage variations without having to use battery power, can filter out line noise and control frequency. Ferroresonant units operate in the same way as a standby UPS unit; however, they are online with the exception that a ferroresonant transformer , is used to filter

8134-471: The protected equipment. Almost all UPSs also contain integrated surge protection to shield the output appliances from voltage spikes . A UPS is typically used to protect hardware such as computers , hospital equipment, data centers , telecommunications equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss . UPS units range in size from ones designed to protect

8232-405: The relatively simple charging systems employed for lead–acid type batteries. Whilst lead–acid batteries can be charged by simply connecting a dynamo to them, with a simple electromagnetic cut-out system for when the dynamo is stationary or an over-current occurs, the Ni–Cd battery under a similar charging scheme would exhibit thermal runaway, where the charging current would continue to rise until

8330-587: The relatively steady 1.2 V of a Ni–Cd cell is enough to allow operation. Some would consider the near-constant voltage a drawback as it makes it difficult to detect when the battery charge is low. Ni–Cd batteries used to replace 9 V batteries usually only have six cells, for a terminal voltage of 7.2 volts. While most pocket radios will operate satisfactorily at this voltage, some manufacturers such as Varta made 8.4 volt batteries with seven cells for more critical applications. Ni–Cd batteries can be charged at several different rates, depending on how

8428-409: The rotational inertia of the flywheel can be used to directly start up a diesel engine, and once running, the diesel engine can be used to directly spin the flywheel. Multiple flywheels can likewise be connected in parallel through mechanical countershafts , without the need for separate motors and generators for each flywheel. They are normally designed to provide very high current output compared to

8526-425: The same EU directive, used industrial Ni–Cd batteries must be collected by their producers in order to be recycled in dedicated facilities. Uninterruptible power supply An uninterruptible power supply ( UPS ) or uninterruptible power source is a type of continual power system that provides automated backup electric power to a load when the input power source or mains power fails. A UPS differs from

8624-676: The same sizes as alkaline batteries , from AAA through D, as well as several multi-cell sizes, including the equivalent of a 9-volt battery. A fully charged single Ni–Cd cell, under no load, carries a potential difference of between 1.25 and 1.35 volts, which stays relatively constant as the battery is discharged. Since an alkaline battery near fully discharged may see its voltage drop to as low as 0.9 volts, Ni–Cd cells and alkaline cells are typically interchangeable for most applications. In addition to single cells, batteries exist that contain up to 300 cells (nominally 360 volts, actual voltage under no load between 380 and 420 volts). This multi-cell design

8722-411: The shelf life of the battery. If treated well, a Ni–Cd battery can last for 1,000 cycles or more before its capacity drops below half its original capacity. Many home chargers claim to be "smart chargers" which will shut down and not damage the battery, but this seems to be a common problem. Ni–Cd batteries contain between 6% (for industrial batteries) and 18% (for commercial batteries) cadmium , which

8820-505: The temperature will rise to 45–50 °C. Some battery chargers detect this temperature increase to cut off charging and prevent over-charging. When not under load or charge, a Ni–Cd battery will self-discharge approximately 10% per month at 20 °C, ranging up to 20% per month at higher temperatures. Note; year 2022, the preceding sentence was certainly true when NiCad was introduced and even 50 years ago. However continued improvements seen around 40 years ago lead to 5% per month and today

8918-462: The transformer output is too low to charge the batteries. Autotransformers can be engineered to cover a wide range of varying input voltages, but this requires more taps and increases complexity, as well as the expense of the UPS. It is common for the autotransformer to cover a range only from about 90 V to 140 V for 120 V power, and then switch to battery if the voltage goes much higher or lower than that range. In low-voltage conditions

9016-468: The use of ordinary AC-powered equipment. Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking and anti- islanding protection. The output of some electronic UPSes can have a significant departure from an ideal sinusoidal waveform. This is especially true of inexpensive consumer-grade single-phase units designed for home and office use. These often utilize simple switching AC power supplies and

9114-418: The voltage to return to normal. However, if the device is unable to operate through this period of decreased voltage, it will be unable to get enough energy out of the battery, and for all practical purposes, the battery appears "dead" earlier than normal. There is evidence that the memory effect story originated from orbiting satellites, where they were similarly charging and discharging with every orbit around

9212-406: The wiring supplying power to the UPS due to the spikes in current flow. This level of "noise" is measured as a percentage of " total harmonic distortion of the current " (THD I ). Classic UPS rectifiers have a THD I level of around 25%–30%. To reduce voltage distortion, this requires heavier mains wiring or generators more than twice as large as the UPS. There are several solutions to reduce

9310-399: Was created by Waldemar Jungner of Sweden in 1899. At that time, the only direct competitor was the lead–acid battery , which was less physically and chemically robust. With minor improvements to the first prototypes, energy density rapidly increased to about half of that of primary batteries, and significantly greater than lead–acid batteries. Jungner experimented with substituting iron for

9408-504: Was released in 1983. The Rolleiflex SL2000F takes the same lenses as the Rollei SL35, which use the QBM (quick bayonet mount) interface. Some lenses were designed by Carl Zeiss AG and manufactured by Rollei under license, while others were designed and manufactured by Zeiss. In addition, Rollei manufactured a lower-cost line of Rolleinar MC lenses for QBM. The standard magazine back requires

9506-463: Was shown at photokina '84, increasing the fastest shutter speed and adding a grip to the right side of the camera; it required the NiCd battery pack. The SL2000F body includes both eye- and waist-level finders. The SL2000F offers motorized film advance at up to an observed three frames per second, powered by a battery pack that attaches to the rear of the film magazine; either five AA batteries can be used, or

9604-489: Was written by GE scientists at their Battery Business Department in Gainesville, Florida, and later retracted by them, but the damage was done. The battery survives thousands of charges/discharges cycles. Also it is possible to lower the memory effect by discharging the battery completely about once a month. This way apparently the battery does not "remember" the point in its charge cycle. An effect with similar symptoms to

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