Top 10 Power Capacitor Brand & Manufacturers

What is a Power Capacitor?

A power capacitor is a type of capacitor designed to handle high - voltage and high - power applications. It stores electrical energy in an electric field between two conductive plates separated by a dielectric material. When a voltage is applied across the capacitor, electric charges accumulate on the plates, creating an electric field and storing energy. Power capacitors are used to improve the power factor, reduce power losses, and stabilize voltage in power - distribution systems and various electrical equipment.

History of Power Capacitor

• Early Developments: The concept of capacitance dates back to the 18th century with the experiments of scientists like Pieter van Musschenbroek and Ewald Georg von Kleist. However, early capacitors were relatively simple and had limited applications. The development of power capacitors began in the early 20th century as the need for efficient power - transmission and - distribution grew. Early power capacitors were mainly used to correct power factor in industrial power systems.
• Technological Advancements: With the development of new dielectric materials, such as impregnated paper, plastic films (like polypropylene), and later, ceramic and mica - based materials, the performance of power capacitors improved significantly. These materials allowed for higher voltage ratings, increased energy - storage capacity, and better reliability. The manufacturing processes also became more refined, enabling the production of capacitors with more consistent capacitance values and improved electrical insulation.
• Modern Developments: In modern times, power capacitors have become more advanced and specialized. There are now power capacitors designed for specific applications, such as in high - voltage direct - current (HVDC) transmission systems, renewable - energy generation (like wind and solar power), and advanced industrial - automation equipment. The integration of power capacitors with power - electronics devices and smart - grid technologies has also become more prevalent, allowing for more efficient power - management and - control.

Purpose of Power Capacitor

• Power - Factor Correction: In electrical power systems, many loads (such as induction motors and fluorescent lights) have a lagging power factor. A power capacitor connected in parallel to the load can improve the power factor by supplying reactive power. This reduces the reactive current drawn from the power source, minimizing power losses in the transmission lines and transformers and improving the overall efficiency of the power - distribution system.
• Voltage Regulation: Power capacitors can be used to regulate voltage in power systems. By storing and releasing electrical energy, they can help to stabilize the voltage level, especially during periods of high - load or fluctuating - load conditions. In distribution substations, capacitor banks are often used to maintain a relatively constant voltage supply to consumers.
• Energy Storage in Power - Electronics Applications: In power - electronics circuits such as in inverters and converters, power capacitors are used to store energy and smooth out the voltage and current waveforms. For example, in a switched - mode power supply, the power capacitor filters out the high - frequency ripple and provides a more stable DC output voltage.
• Harmonic Filtering: In power systems with non - linear loads (which generate harmonics), power capacitors can be part of harmonic - filtering circuits. They can help to reduce the distortion of the voltage and current waveforms by providing a path for the harmonic currents, thereby improving the power quality.

Principle of Power Capacitor

• Capacitance and Electric Field: The capacitance $C$ of a capacitor is given by the formula $C=frac{epsilon A}{d}$, where $epsilon$ is the permittivity of the dielectric material, $A$ is the area of the conductive plates, and $d$ is the distance between the plates. When a voltage $V$ is applied across the capacitor, the charge $Q$ stored on the capacitor is related to the capacitance and voltage by $Q = CV$. The energy $W$ stored in the capacitor is given by $W=frac{1}{2}CV^{2}$. The electric field $E$ between the plates is related to the voltage and the distance between the plates by $E=frac{V}{d}$. The dielectric material's ability to withstand the electric field without breakdown is a crucial factor in the design and operation of power capacitors.
• Reactive Power and Power - Factor Improvement: In an AC circuit, the current through a capacitor leads the voltage by 90 degrees. The reactive power $Q_{C}$ supplied by a capacitor is given by $Q_{C}=V^{2}omega C$, where $omega$ is the angular frequency of the AC voltage. By adding a power capacitor to a circuit with a lagging - power - factor load, the capacitor supplies the reactive power, reducing the reactive component of the current drawn from the source and improving the power factor.[!--empirenews.page--]

Features of Power Capacitor

• High - Voltage Rating: Power capacitors are designed to withstand high voltages. They can have voltage ratings ranging from a few kilovolts (kV) to several hundred kV, depending on the application. The high - voltage rating allows them to be used in power - transmission and - distribution systems and in high - voltage equipment such as high - voltage motors and transformers.
• High - Capacitance Values: Power capacitors typically have relatively high capacitance values, measured in microfarads ($mu F$) to millifarads ($mF$). The high - capacitance values enable them to store significant amounts of electrical energy and have a more pronounced effect on power - factor correction and voltage regulation.
• Low - Loss Tangent: The loss tangent ($tandelta$) of a power capacitor is a measure of the energy losses in the capacitor. A low - loss tangent indicates that the capacitor is more efficient in storing and releasing energy. High - quality power capacitors have a low - loss tangent, which is important for minimizing power losses in applications such as power - factor correction and energy - storage systems.
• Self - Healing Property: Many modern power capacitors, especially those with plastic - film dielectrics, have a self - healing property. If a small defect or breakdown occurs in the dielectric material, the capacitor can self - heal by isolating the affected area and maintaining its overall functionality. This property improves the reliability and lifespan of the capacitor.
• Thermal Stability: Power capacitors need to have good thermal stability. They are designed to operate over a wide range of temperatures without significant degradation of their performance. In applications where the capacitor may be subject to temperature variations, such as in outdoor power - distribution systems, the thermal stability of the capacitor is crucial for its long - term operation.

Types of Power Capacitor

• Film Capacitors: These capacitors use a plastic - film dielectric, such as polypropylene or polyester. Film capacitors have a wide range of capacitance values and voltage ratings. They are known for their high - insulation resistance, low - loss tangent, and self - healing properties. Film power capacitors are used in a variety of applications, including power - factor correction, energy - storage systems, and power - electronics circuits.
• Ceramic Capacitors: Ceramic - based power capacitors have a ceramic dielectric material. They can have high - capacitance values in a small physical size. Ceramic capacitors are suitable for high - frequency applications and can handle high - voltage pulses. However, their capacitance can vary with temperature and voltage, and they may have a higher loss tangent compared to film capacitors in some cases.
• Electrolytic Capacitors: These capacitors use an electrolyte as one of the electrodes and a metal oxide as the dielectric. Electrolytic capacitors can have very high - capacitance values, making them useful for applications where a large amount of energy storage is required in a relatively small space. However, they have a polarity (they are polarized capacitors), and incorrect polarity connection can lead to damage or even explosion. They are mainly used in DC - power - supply circuits and some low - frequency AC applications.
• Capacitor Banks: A capacitor bank is a group of capacitors connected together. They are used in power - distribution systems to provide a large amount of reactive power for power - factor correction and voltage regulation. Capacitor banks can be fixed or adjustable, depending on the requirements of the power - system operation.

Precautions for using Power Capacitor

• Over - Voltage Protection: Power capacitors must not be subjected to voltages that exceed their rated voltage. Over - voltage can lead to dielectric breakdown, which can cause the capacitor to short - circuit or even explode. Use appropriate voltage - protection devices such as surge arresters and over - voltage relays to protect the capacitor from voltage surges.
• Over - Temperature Protection: Monitor the temperature of the power capacitor during operation. High - temperature conditions can accelerate the degradation of the dielectric material and other components, reducing the capacitor's lifespan and performance. Ensure proper ventilation and consider using temperature - sensing devices and cooling mechanisms if necessary.
• Reactive - Power Control: When using power capacitors for power - factor correction, carefully calculate and control the amount of reactive power supplied. Incorrect sizing or over - compensation of reactive power can lead to problems such as over - voltages and resonance in the power system.[!--empirenews.page--]
• Dielectric Integrity: The dielectric material is a critical part of the power capacitor. Any damage to the dielectric, such as cracks, punctures, or contamination, can lead to performance degradation or failure. Inspect the capacitor for any signs of dielectric damage before installation and during maintenance.
• Polarity (for Electrolytic Capacitors): If using electrolytic power capacitors, pay strict attention to the polarity. Connecting the capacitor with the wrong polarity can cause damage and is a safety hazard. Always follow the manufacturer's instructions regarding the correct connection of polarized capacitors.

Things to consider when purchasing Power Capacitor

• Application Requirements: Determine the specific requirements of the application. Consider the voltage rating, capacitance value, frequency range, and the need for power - factor correction, voltage regulation, or energy storage. For example, if you are designing a power - factor - correction system for an industrial plant, you need to calculate the required capacitance based on the load characteristics and the desired power - factor improvement.
• Type of Capacitor: Based on the application, select the appropriate type of power capacitor. For high - voltage and high - power - factor - correction applications, film capacitors or capacitor banks may be suitable. For high - frequency and small - space - limited applications, ceramic capacitors might be a better choice. Consider the advantages and disadvantages of each type in terms of capacitance stability, loss tangent, and self - healing properties.
• Performance Characteristics: Look at the voltage rating, capacitance tolerance, loss tangent, and self - healing ability. The voltage rating should be sufficient to handle the operating voltage of the application. The capacitance tolerance should be within an acceptable range to ensure the expected performance. A low - loss tangent and good self - healing properties are desirable for efficient and reliable operation.
• Size and Physical Dimensions: Consider the physical size of the capacitor. It should fit into the available space in your equipment or installation. The size of the capacitor is related to its capacitance value, voltage rating, and the type of dielectric material used. In some applications, such as in compact power - electronics equipment, small - sized capacitors are preferred.
• Cost and Budget: Establish a budget for the power - capacitor purchase. The cost can vary depending on the type, performance, and brand of the capacitor. Consider not only the initial purchase price but also the long - term costs such as maintenance, potential replacement due to failures, and energy losses during operation. A more expensive capacitor with better performance and reliability may be a more cost - effective choice in the long run for some applications.
• Manufacturer Support and Training: Select a reputable manufacturer that provides good technical support and training. Operating and using power capacitors correctly may require some technical knowledge, and the manufacturer should offer resources such as user manuals, online tutorials, and customer support to help you get the most out of the device.

Terms of Power Capacitor

• Capacitance ($C$): A measure of the ability of a capacitor to store electrical charge. It is defined as the ratio of the charge stored on the capacitor to the voltage across it. The unit of capacitance is the farad (F), but in power - capacitor applications, microfarads ($mu F$) and millifarads ($mF$) are more commonly used.
• Dielectric Constant ($epsilon_{r}$): The ratio of the permittivity of the dielectric material to the permittivity of free space. It affects the capacitance value of the capacitor. A higher dielectric constant allows for a higher capacitance for a given plate area and distance between the plates.
• Loss Tangent ($tandelta$): A measure of the energy losses in a capacitor. It is the ratio of the energy dissipated as heat to the energy stored in the capacitor. A low - loss tangent indicates a more efficient capacitor.
• Power - Factor ($PF$): In an AC circuit, the power - factor is the ratio of the real power (in watts) to the apparent power (in volt - amperes). Power capacitors are used to improve the power - factor of a circuit by supplying reactive power.
• Self - Healing: A property of some capacitors, especially film capacitors, where the capacitor can recover from a small dielectric breakdown by isolating the affected area and continuing to function. This property enhances the reliability of the capacitor.