Related Topics:
Mylar Polyester Film Capacitor-
Polypropylene capacitors vs film capacitors
The film capacitor is a non-polarized capacitor and its dielectric is made using thin plastic films. These plastic films are sometimes metalized and are available in the market under the name “metalized capacitor”. Th. Before film capacitors came in to picture, paper capacitors were used in the decoupling circuits. Paper capacitorsused impregnated paper which was placed with metal strips and r. Soon after the first film capacitor was introduced, the plastic industry saw its growth in developing thinner and more durable products. Different types of plastic film capacitors ha. As the name suggests, the film/foil capacitor uses plastic films as dielectric and is placed inside two layers of electrodes made of aluminum foil. These interleaved layers are so stru. The main difference between a film foil capacitor and a metalized capacitor is that in the latter instead of layering, the metallic electrodesare fused into either side of the plastic dielectric.
[PDF Version]
FAQs about Polypropylene capacitors vs film capacitors
What is a polypropylene film capacitor?
The Polypropylene Capacitor is another type of Film Capacitor in which the dielectric material is made of a polymer caller polypropylene (PP), hence the name Polypropylene Film Capacitor or PP Film Capacitor. A typical polypropylene capacitor is shown below
Which polymer is best for film capacitors?
Polymers in Film Capacitors - The Next Generation Material is available! Polypropylene is the polymer of choice for most film capacitors, but there is an inherent high temperature limit for its usage. New polymer materials are therefore required to overcome these temperature limitations.
What are the different types of film capacitors?
There are many types of Film Capacitors based on the type of plastic dielectric material used in the capacitor, out of which Polyester Capacitor and Polypropylene Capacitors are the most commonly used one.
Why are new polymer materials needed for capacitor films?
New polymer materials are therefore required to overcome these temperature limitations. Accordingly, a new class of engineering materials, EPN (Ethylene-Propylene-Norbornene), has been developed for capacitor films, combining the advantages of polypropylene and cyclic olefin copolymers.
Are polypropylene film/foil capacitors suitable for low pulse applications?
Polypropylene film/foil capacitors are commonly used as snubber capacitors in low pulse applications. In comparison, polypropylene metallized film capacitors and double-sided metallized film capacitors have a self-healing property, and they are suitable for use in low pulse and medium pulse applications.
Are polyester capacitors good?
Polyester capacitors are regarded as “general purpose capacitors”. They provide the best volume efficiency of all film capacitors at moderate cost and are preferably used for DC applications such as decoupling, blocking, bypassing and noise suppressions. Polypropylene film has superior electrical characteristics.
-
Smart capacitor contactor symbol
In the previous lesson, electromagnetic relays were described in quite some detail. An electromagnetic contactor can be compared to a relay because the principle of operation is very similar: when the coil of the contactor is energized, the main contacts of the contactor close (short-circuit). The main difference. The contactor symbol consists of three parts: coil, main contacts and auxiliary contacts. 1. There can only be one coil in a contactor. 2. The main contacts of a contactor are three and. To explain the operation of the contactor, I have prepared a diagram (Fig. 5.) with the option of self-sustained motor operation. Thanks to the parallel.
FAQs about Smart capacitor contactor symbol
What does a capacitor symbol mean?
The symbol for a capacitor is composed of one or two circles with plus and minus signs inside, representing the two terminals that connect it to the circuit. Other symbols include resistance, relay, transformer, LED and motor. Understanding the meanings behind these symbols is an important skill for any electrician.
Which contactors are suited for capacitor bank switching?
Application The A...and AF...contactors are suited for capacitor bank switching for the peak current and power values in the table below. The capacitors must be discharged (maximum residual voltage at terminals < 50 V)before being re-energized when the contactors are making.
What is a capacitor contactor?
The contactors for capacitor switching is actually composed of a conventional contactor as well as extra auxiliary contacts and wires (resistance wires). The main function of the capacitor contactor lies in the auxiliary contact, which is very different from the conventional contact.
What are the different types of capacitor symbols?
Other symbols include a rectangle with one straight side and one curved or absent side, and variations for specific types like variable capacitors (with an arrow indicating adjustability) and trimmer capacitors (with a diagonal line through the parallel lines).
What is a contactor symbol?
The contactor symbol consists of three parts: coil, main contacts and auxiliary contacts. There can only be one coil in a contactor. The main contacts of a contactor are three and are always drawn as one symbol in the form of three contacts. The auxiliary contacts, as a symbol, are used in the same way as the relay contacts.
What is a non-polarized capacitor symbol?
Non-Polarized Capacitor Symbol Symbol: Two parallel lines of equal length. Explanation: This is the most general symbol for capacitors. It represents capacitors that can be connected in any direction within a circuit without affecting their performance or causing damage.
-
Capacitor protection opening voltage
This overcurrent relay detects an asymmetry in the capacitor bankcaused by blown internal fuses, short-circuits across bushings, or between capacitor units and the racks in which they are mounted. Each capacitor unit consist of a number of elements protected by internal fuses. Faulty elements in a capacitor unit are. Capacitors of today have very small losses and are therefore not subject to overload due to heating caused by overcurrent in the circuit. The capacitor. In addition to the relay functions described above the capacitor banks needs to be protected against short circuits and earth faults. This is done with an.
FAQs about Capacitor protection opening voltage
Does a capacitor need overload protection?
Given that the capacitor can generally accommodate a voltage of 110% of its rated voltage for 12 hours a day, this type of protection is not always necessary. Overcurrent of long duration due to the flow of harmonic current is detected by an overload protection of one the following types:
What is capacitor bank protection?
Capacitor Bank Protection Definition: Protecting capacitor banks involves preventing internal and external faults to maintain functionality and safety. Types of Protection: There are three main protection types: Element Fuse, Unit Fuse, and Bank Protection, each serving different purposes.
How do you protect a shunt capacitor?
Bank Protection Methods: Use voltage and current sensitive relays to detect imbalances and protect the bank from excessive stress and damage. Like other electrical equipment, a shunt capacitor can experience internal and external electrical faults. Therefore, it needs protection from these faults.
How to protect a capacitor bank from a short circuit?
3. Short circuit protection In addition to the relay functions described above the capacitor banks needs to be protected against short circuits and earth faults. This is done with an ordinary two- or three-phase short circuit protection combined with an earth overcurrent relay.
What happens when a capacitor bank is protected by a fuse?
Whenever the individual unit of capacitor bank is protected by fuse, it is necessary to provide discharge resistance in each of the units. While each capacitor unit generally has fuse protection, if a unit fails and its fuse blows, the voltage stress on other units in the same series row increases.
Why are capacitors not subject to overload?
Capacitors of today have very small losses and are therefore not subject to overload due to heating caused by overcurrent in the circuit. Overload of capacitors are today mainly caused by overvoltages. It is the total peak voltage, the fundamental and the harmonic voltages together, that can cause overload of the capacitors.
-
Capacitor epoxy encapsulation material
Compared to the vast majority, capacitor attachment via conductive epoxy is not a common technique among end-user applications. A significant amount of growth in capacitor usage has occurred in solder attachment methods. Furthermore, many publications on attachment methods focus predominantly on. Conductive Epoxy Attachment Basics Conductive Epoxy attachment is an alternative attachment method of soldering. As the name indicates, a conductive glue replaces solder during the attachment of a device to. For decades electrically conductive epoxies have been used as an assembly method in applications such as microelectronics, lead frames, and hybrid microcircuits. SMT components used in conductive epoxy processes must be compatible with the hydroscopic nature of electrically conductive epoxies. Conductive epoxy attachment offers a very. When selecting SMT components, extreme care must be exercised in conductive epoxy applications since not all SMT component.
[PDF Version]
FAQs about Capacitor epoxy encapsulation material
What materials are used for capacitor encapsulation?
The commonly used capacitor encapsulation materials include epoxy resin, polyurethane, silicone, etc. Epoxy resin embodies high mechanical strength, low moisture absorption, low ther-mal expansion coeficient and good cold and thermal shock resistance.
What is encapsulation epoxy?
Encapsulation epoxy adds mechanical strength to electronic assemblies, reducing the risk of physical damage during handling, transportation, and operation. It helps to secure delicate components and connections, preventing mechanical stress and vibration from causing damage. **3.3. Electrical Insulation
What materials are used for encapsulation?
These materials were eventually substituted with polymers, and the most preferred material choices for encapsulation today are epoxy resins, silicones, and polyurethanes. These three materials have varying significant characteristics that make them suitable for different encapsulation applications.
Is conductive epoxy a good way to attach a capacitor?
Compared to the vast majority, capacitor attachment via conductive epoxy is not a common technique among end-user applications. A significant amount of growth in capacitor usage has occurred in solder attachment methods.
What is electronic encapsulation?
In this process, a pre-formed part or, in the case of electronics encapsulation, an electronic component is placed within the mold and the heated raw material is injected into the mold to form a protective layer around the electronic component. Another process that can be used to encapsulate electronics is transfer molding.
How do I choose a conductive epoxy?
The selection of a specific conductive epoxy is not simple. At a minimum, epoxy types can be one-part, two-part, or silicone-based. Whichever option is chosen for the “carrier” material, its purpose is to suspend the conductive metal particle in the carrier fluid until they are dispensed and cured.
-
Nairobi capacitor company ranking
A is a passive device on a circuit board that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. This is a list of known manufacturers, their headquarters country of origin, and year founded. The oldest capacitor companies were founded over 100 years ago. Most older companies were founded during the era, which includes the era and post war era. As the de.
FAQs about Nairobi capacitor company ranking
What are the top ranked capacitor companies?
This section provides an overview for capacitors as well as their applications and principles. Also, please take a look at the list of 42 capacitor manufacturers and their company rankings. Here are the top-ranked capacitor companies as of January, 2025: 1.CDE, 2.Vishay Intertechnology, Inc.,, 3.United Chemi-Con.
Who makes optimal power capacitors?
CDE, founded in Liberty, SC in 1909 is a manufacturer of optimal power capacitors. The company's product portfolio includes electrolytic capacitors, mica capacitors, AC film capacitors, DC film capacitors and Power Factor Correction Capacitors.
Why are capacitor manufacturers important?
Most older companies were founded during the AM radio era, which includes the World War II era and post war era. As the demand for advanced electronics continues to grow, the role of capacitor manufacturers becomes increasingly vital, supporting crucial domains like consumer electronics, power systems, automotive technology, and telecommunications.
What are the top companies in Kenya?
In Kenya, Total is one of the top companies by revenue. The company helps keep Kenya's cars and trucks moving. It plays a big role in the country's economy. Total Kenya is known for its good quality products and services. KenolKobil is a major player in Kenya's oil and energy sector.
Why are Kenya's Top 100 companies important?
Kenya's top 100 companies play a crucial role in shaping the nation's economy. These businesses drive growth, create jobs, and contribute significantly to the country's overall economic health. The top 100 companies in Kenya are major contributors to the country's Gross Domestic Product (GDP).
Is total Kenya a good company?
Total Kenya is part of a bigger company called TotalEnergies. This company works in many countries around the world. In Kenya, Total is one of the top companies by revenue. The company helps keep Kenya's cars and trucks moving. It plays a big role in the country's economy. Total Kenya is known for its good quality products and services.
-
Var common compensation distribution capacitor
In, a static VAR compensator (SVC) is a set of electrical devices for providing fast-acting on networks. SVCs are part of the device family, regulating voltage, power factor, harmonics and stabilizing the system. A static VAR compensator has no significant moving parts (other than internal switchgear). Prior to the invention of the SVC, power factor compensation was the pres.
FAQs about Var common compensation distribution capacitor
What are the different types of static VAR Compensator (SVC)?
At least four different types of static Var compensator (SVC) are available. These are: STATCOM (Static Compensator). Go back to Content Table ↑ The Power Transmission Division of GEC, Stafford, was the pioneer of saturated reactor type compensator.
Are static VAR compensators more expensive than mechanically switched capacitors?
However, static VAR compensators are more expensive than mechanically switched capacitors, so many system operators use a combination of the two technologies (sometimes in the same installation), using the static VAR compensator to provide support for fast changes and the mechanically switched capacitors to provide steady-state VARs.
Can static VAR compensator and capacitor bank improve transmission line performance?
Application of static var compensator (SVC) and capacitor bank as a way to improve the voltage profile and power loss. In this study, the two types of equipment were used to increase the performance of the transmission line with case study 150 kV Nort Sumatra of electric power transmission line.
What is static VAR compensator function in electronic power supply systems?
Static VAR Compensator function in electronic power supply systems is Improve the power supply environment. As a result, reactive power compensation devices are vital and essential components in power supply systems. A rational selection of compensating devices can reduce network losses & improve grid quality.
What is control and protection system of static VAR compensator?
Control and protection system of the static var compensator provides quick reactive power load, while maintaining controlled parameter, protecting SVC equipment, monitoring and signalizing failures and it also can be tailored in compliance with customer's wishes.
How do you manage a static VAR Compensator (SVC)?
Effective management of Static VAR Compensators (SVCs) relies heavily on sophisticated control systems. These mechanisms ensure that SVCs respond quickly and accurately to changing electrical conditions. Control strategies for SVCs can be categorized into two main types:
-
Why does the capacitor break down
The classic capacitor failure mechanism is dielectric breakdown. The dielectric in the capacitor is subjected to the full potential to which the device is. Open capacitors usually occur as a result of overstress in an application. For instance, operation of DC rated capacitors at high AC current levels. The following list is a summary of the most common environmentally "critical factors" with respect to capacitors. The design engineer must take into consideration his own applications and the effects caused by combinations of various.
-
Power supply capacitor transformer
Determining the power dissipation of the components in the circuit is a critical consideration. As a general rule, components should be selected with power ratings at least twice the maximum power calculated for each. Advantages of Resistive Power Supply: Significantly smaller than a transformer-based power supply. Lower cost than a transformer-based power. Advantages of Capacitive Power Supply: Significantly smaller than a transformer-based power supply. More cost effective than a transformer-based or switcher-based power supply. Selecting component power rating in the circuit is a critical consideration. As a general rule, components should be sized at twice the maximum. A capacitive power supply or capacitive dropper is a type of that uses the of a to reduce higher to a lower voltage. It is a relatively inexpensive method compared to typical solutions using a, however, a relatively large mains-voltage capacitor is required an.
[PDF Version]
-
Capacitor external fault protection
Manufacturers usually include built-in fuses in each capacitor element. If a fault occurs in an element, it is automatically disconnected from the rest of the unit. The unit can still function, but with reduced output. For smaller capacitor banks, only these built-in protection schemes are used to avoid the cost of additional protective. Unit fuse protection limits the duration of arc in faulty capacitor units. This reduces the risk of major mechanical damage and gas production, protecting. While each capacitor unit generally has fuse protection, if a unit fails and its fuse blows, the voltage stress on other units in the same series row increases. Each capacitor unit is designed.
FAQs about Capacitor external fault protection
What is capacitor bank protection?
Capacitor Bank Protection Definition: Protecting capacitor banks involves preventing internal and external faults to maintain functionality and safety. Types of Protection: There are three main protection types: Element Fuse, Unit Fuse, and Bank Protection, each serving different purposes.
Why do capacitor banks need unbalance protection?
Capacitor banks require a means of unbalance protection to avoid overvoltage conditions, which would lead to cascading failures and possible tank ruptures. Figure 7. Bank connection at bank, unit and element levels. The primary protection method uses fusing.
What are the different types of protection arrangements for capacitor bank?
There are mainly three types of protection arrangements for capacitor bank. Element Fuse. Bank Protection. Manufacturers usually include built-in fuses in each capacitor element. If a fault occurs in an element, it is automatically disconnected from the rest of the unit. The unit can still function, but with reduced output.
What are the different types of capacitor protection?
Types of Protection: There are three main protection types: Element Fuse, Unit Fuse, and Bank Protection, each serving different purposes. Element Fuse Protection: Built-in fuses in capacitor elements protect from internal faults, ensuring the unit continues to work with lower output.
What is a shunt capacitor bank?
Shunt capacitor banks, also called filter banks, are widely used in transmission and distribution networks to produce reactive power support. ABB's capacitor bank protection is used to protect against faults that are due to imposed external or internal conditions in the shunt capacitor banks.
What are the main faults liable to affect capacitor banks?
The main faults which are liable to affect capacitor banks are: 1. Overload An overload is due to temporary or continuous overcurrent: Continuous overcurrent linked to: Temporary overcurrent linked to the energizing of a capacitor bank step.
-
Factory compensation capacitor bank wiring
Having above information, it is possible to find fitting cubicle for the elements of the capacitor bank. Because the device is going to operate at the mains, where higher order harmonics are present, power capacitors must be protected by reactors. Each capacitor emits additional amount of heat as well as a reactor. The. The arrangement of the elements inside the enclosure should be easily available for maintenance and replacement, and each element should be clearly marked according to the technical. The next step is to chose appropriate power capacitors. It means, that one needs to pay attention to its rated voltage and power. Since the capacitors will be working in series with reactors, what will cause the voltage at the. The short circuit protection of the capacitors is provided by the switch disconnectors. For the capacitors the fuse link rated current should be 1.6 time of the rated reactive current of the capacitor. In=Q / (Un×√3) where: 1. The last step is to select the protection of the capacitors as well as the contactors. In order to do so, one has to skim the catalogue cards of the manufacturers. Contactors for the capacitor banks are specially designed, taking.
[PDF Version]
FAQs about Factory compensation capacitor bank wiring
Why are capacitor banks installed?
Capacitor banks are mainly installed to provide capacitive reactive compensation/ power factor correction. Normally in factories or other high power consuming places, most probably there will be a consumption of the inductive load. Inductive voltage means that there must be a lagging power factor.
What is a capacitor bank wiring diagram?
Capacitor banks are used in many industries, including power distribution, motor control, and energy storage. As such, the wiring diagram must be accurate and detailed to ensure that everything functions as it should. To create a capacitor bank wiring diagram, you will need to understand the different components and their interconnections.
What is the purpose of capacitor bank calculator?
The main purpose of the capacitor bank calculator is to get the necessary kVAR for enhancing power factor (pf) from low range to high. For that, the required values are; current power factor, real power & the value of power factor to be enhanced over the system. So that we can calculate to get the value in kVAR.
What is the detuning factor of a capacitor bank?
Since the detuning factor for the project was given as p=7%, one knows that the capacitor bank needs to be equipped with reactors. For this reason, some calculations have to be performed, in order to fit the power of the capacitors and its rated voltage taking into account reactive power of a detuning reactors.
Which capacitor bank should I Choose?
If the power of the capacitors (in kvar) is less than 15% of the power of the transformer (in kva), choosing a fixed capacitor bank will definitely provide the best cost/savings compromise. If the power of the capacitors (in kvar) is more than 15% of the power of the transformer, a step capacitor bank with automatic regulation must be chosen.
Why do you need a wiring diagram panel capacitor bank?
Having a wiring diagram panel capacitor bank installed is beneficial for both businesses and consumers. Not only does it help regulate current flow more efficiently, but it also helps protect machines and equipment from unexpected voltage drops and surges.
-
Capacitor exits operation first
by Lewis Loflin Follow @Lewis90068157 Capacitors are components constructed by placing two conductive plates (usually metal) in closeproximity with each other. There are many different styles of capacitorconstruction, each one suited for particular ratings and purposes. For very small capacitors, two circular plates. There are three basic factors of capacitor construction determining theamount of capacitance created. These factors all dictate capacitance byaffecting how much electric field flux (relative. When capacitors are connected in series, the total capacitance is lessthan any one of the series capacitors' individual capacitances. If twoor. Capacitors, like all electrical components, have limitations which mustbe respected for the sake of reliability and proper circuit operation. Working voltage: Since capacitors are nothing more than twoconductors separated.
[PDF Version]
FAQs about Capacitor exits operation first
What is the failure mode of a capacitor?
Electromigration is one of failure mechanisms of semiconductor, but the failure mode can appear as a short, open, or characteristic degradation. Capacitors have several failure modes, the degree of which depends on the type of capacitor (Table 1).
What is a capacitor & how does it work?
A capacitor, or “ cap ” for short, is an electronic device that stores electrical energy in the form of electric charges on two conductive surfaces that are insulated from one another by a dielectric material. A capacitor is a common and widely used electrical component that serves various functions and applications.
What are the different types of capacitor failure?
Capacitor failures can be described by two basic failure categories: catastrophic failures and degraded failures. Catastrophic failure is the complete loss of function of the capacitor in a circuit. Catastrophic failure, such as open or short circuit, is the complete loss of function of the capacitor.
What is a catastrophic failure of a capacitor?
Catastrophic failure is the complete loss of function of the capacitor in a circuit. Catastrophic failure, such as open or short circuit, is the complete loss of function of the capacitor. This failure can cause the enclosure to explode, smoke, ignite, harm other electrical components, or leak liquid or gas from inside the capacitor.
How long does it take a capacitor to self dissipate?
Depending on the specific type of capacitor, the time it takes for a stored voltage charge to self-dissipate can be a long time (several years with the capacitor sitting on a shelf!). When the voltage across a capacitor is increased, it draws current from the rest of the circuit, acting as a power load.
What happens when a capacitor is faced with a decreasing voltage?
When a capacitor is faced with a decreasing voltage,it acts as a source: supplying current as it releases stored energy (current going out the negative side and in the positive side, like a battery). The ability of a capacitor to store energy in the form of an electric field (and consequently to oppose changes in voltage) is called capacitance.
-
Capacitor consumption battery
Batteries come in many different sizes. Some of the tiniest power small devices like hearing aids. Slightly larger ones go into watches and calculators. Still larger ones run flashlights, laptops and vehicles. Some, such as those used in smartphones, are specially designed to fit into only one specific device. Others, like AAA. Capacitors can serve a variety of functions. In a circuit, they can block the flow of direct current(a one-directional flow of electrons) but allow alternating current to pass. (Alternating currents, like those obtained from household. A battery can store thousands of times more energy than a capacitor having the same volume. Batteries also can supply that energy in a steady,. In recent years, engineers have come up with a component called a supercapacitor. It's not merely some capacitor that is really, really good. Rather, it's sort of some hybridof capacitor.
[PDF Version]
FAQs about Capacitor consumption battery
Can a battery store more energy than a capacitor?
Today, designers may choose ceramics or plastics as their nonconductors. A battery can store thousands of times more energy than a capacitor having the same volume. Batteries also can supply that energy in a steady, dependable stream. But sometimes they can't provide energy as quickly as it is needed. Take, for example, the flashbulb in a camera.
What is the difference between a battery and a capacitor?
The first, a battery, stores energy in chemicals. Capacitors are a less common (and probably less familiar) alternative. They store energy in an electric field. In either case, the stored energy creates an electric potential. (One common name for that potential is voltage.)
What are the advantages of a battery compared to a capacitor?
Batteries can provide a steady and continuous supply of power. They have a higher energy density compared to capacitors, making them suitable for applications that require longer-lasting energy storage. Batteries are commonly used in portable electronic devices, electric vehicles, and grid energy storage systems.
How much power can a capacitor store?
The amount of power that can be stored by any capacitor is directly related to the size of the metal plates within the battery. The larger the plate surface, the more energy the capacitor is able to store.
Can You charge a capacitor with a battery?
However, for devices that need consistent, long-term energy supply, a battery is still the best option. You can easily charge a capacitor using a battery. The charging process is quick, and this is commonly done in circuits where capacitors are used to smooth out power supplies or manage energy flow.
Can a capacitor replace a battery?
Not exactly. While you can use a capacitor to store some energy, its ability to replace a battery is limited due to its low energy storage capacity. Capacitors vs batteries aren't interchangeable, but in specific use cases, capacitors can complement or assist batteries.
-
Why is a capacitor equivalent to voltage
In practice, capacitors deviate from the ideal capacitor equation in several aspects. Some of these, such as leakage current and parasitic effects are linear, or can be analyzed as nearly linear, and can be accounted for by adding virtual components to form an equivalent circuit. The usual methods of can then be applied. In other cases, such as with breakdown voltage, the effe.
FAQs about Why is a capacitor equivalent to voltage
What happens when a voltage is applied across a capacitor?
When an electric potential difference (a voltage) is applied across the terminals of a capacitor, for example when a capacitor is connected across a battery, an electric field develops across the dielectric, causing a net positive charge to collect on one plate and net negative charge to collect on the other plate.
Can a capacitor charge up to 50 volts?
A capacitor may have a 50-volt rating but it will not charge up to 50 volts unless it is fed 50 volts from a DC power source. The voltage rating is only the maximum voltage that a capacitor should be exposed to, not the voltage that the capacitor will charge up to.
What is the difference between a capacitor and a battery?
The only difference is a capacitor discharges its voltage much quicker than a battery, but it's the same concept in how they both supply voltage to a circuit. A circuit designer wouldn't just use any voltage for a circuit but a specific voltage which is needed for the circuit. For one circuit, 12 volts may be needed.
Why do capacitors have different voltage ratings?
In another, 50 volts may be needed. A capacitor with a 50V rating or higher would be used. This is why capacitors come in different voltage ratings, so that they can supply circuits with different voltages, fitting the power (voltage) needs of the circuit.
Can a capacitor charge a battery?
With just the capacitor, one resistor and a battery, then the capacitor will charge until the current stops flowing. Since V = IR, once the current is zero, the voltage across the resistor is zero. If there's no voltage across the resistor, then all the voltage must be across the capacitor. So the battery and capacitor voltages must be the same.
How to choose a capacitor?
Remember that capacitors are storage devices. The main thing you need to know about capacitors is that they store X charge at X voltage; meaning, they hold a certain size charge (1µF, 100µF, 1000µF, etc.) at a certain voltage (10V, 25V, 50V, etc.). So when choosing a capacitor you just need to know what size charge you want and at which voltage.