A capacitor is a tiny but necessary component for electronic circuits as it blocks the flow of direct current while allowing alternating current to pass. It also filters out interference and smoothes the output of power supplies. Therefore, choosing a capacitor ought to be done with the utmost care.
By Srabani Sen
Wednesday, July 14, 2010: A capacitor is a passive electronic component consisting of a pair of conductors separated by an insulator. When a potential difference (in voltage) exists across the conductors, it gives rise to an electric field in the dielectric. This field stores energy and produces a mechanical force between the conductors. An ideal capacitor is characterised by a single constant value—capacitance, which is measured in farads.
Despite a capacitor’s wide applications, the Indian capacitor industry has very few manufacturers in the organised sector. As demand outstripped supply, industry’s requirements are met by imports. Prices of imported capacitors are lower compared to what is available in the domestic market. Further, there are illegally dumped capacitors available within the country, which are markedly cheaper. Due to dependence on imported raw material, high interest rates, dumping of cheap products and poor economies of scale, the Indian capacitor industry has never gained momentum. However, India could do much better if a strong local base for raw materials is in place.
The growth potential for the local market, currently estimated to be about Rs 10 billion, is nearly 20-30 per cent. The volumes are also supposed to grow at 20-25 per cent. However, India has to meet global standards to compete in this industry.
What’s new in the market?
The better a capacitor, the more stable will be the circuit based on it. With end users looking for products that are reliable and efficient, capacitor manufacturers are developing new technologies for capacitors and related products. Capacitor makers are now more focused on R&D activities that further improve capacitor reliability and performance while reducing size and costs.
According to C M Haneef, vice president, Cedicom, currently the most popular types of capacitors are the SMD, chip and screw type. With surface mount technology (SMT) picking up fast, capacitors for surface mount devices (SMD) are used in vast quantities. There are many different types of SMD capacitors ranging from the ceramic variety to the tantalum and electrolytic type. Of these, the ceramic SMD capacitors are the most widely used.
An SMD capacitor consists of a rectangular block of ceramic dielectric in which a number of interleaved precious metal electrodes are contained. This structure gives rise to a high capacitance per unit volume. Tantalum SMD capacitors are widely used to provide capacitance levels that are higher than what can be achieved with ceramic capacitors. As a result of the different construction requirements for tantalum SMT capacitors, different packages are used for them.
Electrolytic capacitors are now being used increasingly in SMD designs. Their very high levels of capacitance, combined with their low cost, make them particularly useful in many areas. Chip capacitors or surface mount capacitors, on the other hand, do not have leads. They are used in aerospace, automotive, general purpose, high voltage, high frequency, microwave and telecommunication applications. Electrostatic chip capacitors or electrolytic surface mount capacitors can be either wet or dry. Wet electrolytic capacitors have a moist electrolyte, while dry or solid electrolytic capacitors do not.
Screw type capacitors are normally used in high voltage areas. Both ends of a screw type capacitor should not have any loose connection or uneven contact; this is to avoid high voltage arching. Screw type capacitors are mainly purchased by switchgear manufacturers, high voltage equipment manufacturers, etc.
Companies are also constantly developing new varieties of capacitors as the needs of the industry are changing fast. Nippon Chemi-Con Corp has developed a new type of capacitor called the nano-hybrid capacitor. These will be introduced as replacements to the normal electric double layer capacitor (EDLC) and will have an energy density several times higher than that of an EDLC.
What key players offer
Deki Electronics is a leading manufacturer of film capacitors with a strong presence in the energy efficient lighting industry.The company was established in technical collaboration with Okaya Electric Industries Company Ltd, Japan in 1984. “Deki has since been producing high quality plastic film capacitors at its state of art, automatic plant imported from Japan, Korea and Italy. The present installed capacity of 745 million pcs/anm makes Deki the largest manufacturer of plastic film capacitors in India,” says Vinod Sharma, managing director, Deki Electronics Ltd.
Deki manufactures plain and metallised polyester, plain and metallised polypropylene, and plain and metallised mixed dielectric capacitors. “We produce complete range of plastic film capacitors that are reliable and internationally competitive. The company’s quality system is certified under ISO 9001: 2008 standards by the Bureau of Indian Standards (since 1994). It has also received ISO 14001: 2004 from BIS for environment management. In addition to this, Deki’s whole range is RoHS complaint. The capacitors are tested by ERTL to IEC standards and approved by CACT for telecom applications.
A major supplier, Arihant Electricals, is an authorised distributor of EPCOS (now it is known as TDK-EPC) make capacitors. “The capacitors supplied by Arihant Electricals include aluminium electrolytic capacitors film cap, power caps and leaded and chip multilayer ceramic caps,” informs Shailendra Singh, senior manager, sales, Arihant Electricals.
Cedicom specialises in the production of high voltage ceramic disc capacitors. “Cedicom ceramic disc capacitors are highly reliable and small in size. We offer capacitors for various applications in consumer electronics, medical electronic equipment, industrial electronic equipment, communications, push button telephones and other professional electronic equipment,” says Haneef.
“The growth of capacitors is directly connected with the growth of power generation, industrialisation and power reforms enforced on end users,” says Sunil Sikka, president, Havells India Ltd. “The key to success in this market is to produce high quality products and fully utilise the range of one’s production facility,” he adds. Havell made a foray into the Indian market in 2007 by opening its capacitor plant in Noida. It manufactures power factor improvement capacitors like normal duty, heavy duty extended life and super heavy duty long life capacitors, and agricultural capacitors, “Havell’s capacitors come with triple safety protection, that is, with mechanical fuse which operates in the event of any fault. These capacitors are designed to improve the power factor. These low voltage capacitors improve active power and reduce reactive power, which helps in saving energy,” says Sikka.
Sumitron Exports Pvt Ltd, a major distributor of capacitors, supplies Nippon (NIC) with manufactures aluminium electrolytic capacitors, tantalum capacitors, film capacitors, ceramic capacitors, multilayer ceramic chip capacitors, etc. “Capacitors are a significant component in the electronics industry. Hence, while the majority say that this component has immense potential for growth, the reality is that in order to harness its popularity, more players need to join the market. However, in India, its manufacture is negligible,” says S K Jain, CEO, Sumitron Exports.
Keltron Component Complex Ltd (KCCL) produces ultra miniature, high standard and highly reliable aluminium electrolytic radial lead capacitors, axial lead capacitors, large can snap-in, lug type, screw type aluminium electrolytic capacitors, motor start capacitors, motor run capacitors, MPP-SH type and AC power capacitors for power factor correction.
“There are only a few Indian manufacturers that are still surviving in the electrolytic capacitor field. Most of the Indian market’s requirement for electrolytic capacitors is being catered to by imported brands. Electrolytic capacitors from China are available in the Indian market in plenty at a very low price. These are being consumed by the small OEMs,” says K Radhakrishnan, managing director, KCCL.
Innovations in capacitors
With every electronics product undergoing continual technological changes, capacitors are also witnessing innovations. The capacitors market is increasingly moving towards components with higher efficiencies in relatively compact sizes. Says Jain, “Technological advancements in ceramic materials used in devices, modules and components, have been instrumental in reducing the size of sub-assemblies and components. However, a regular increase in the transistor density of integrated circuits is perceived to be primarily responsible for the miniaturisation of electronic products and systems.”
Sikka believes that the harmonics levels are increasing day by day due to use of electronics in the heavy industries like cement, steel, textiles, etc, making the process automatic and increasing the total harmonics distortion by up to 30 per cent. “Hence, the detuned harmonics filters—the reactor and capacitor combination—should be used. These will block the harmonics and improve the power factor,” he says.
Haneef of Cedicom agrees, saying, “Even film capacitors are being made halogen free and are ROHS compliant. High energy rating capacitors called super capacitors are being made more efficient for hybrid vehicles, laptops, camera flashes, etc.”
There are different technologies for capacitors like MPP, APP, mixed dielectric, etc.
The latest technology is the metallised polypropylene capacitors that have self healing properties. In case of a puncture in the dielectric due to over voltage or over current, these capacitors ‘self-heal’.
MPP type capacitors are the best option for improving power quality. The entire range of MPP capacitors is meticulously made to provide consumers the best and most consistent performance. “In today’s state of affairs, it has become very important to increase the use of MPP capacitors and improve the power factor in all areas in order to save energy,” says Haneef.
Says Singh, “If any customer requires any specific value, then the inquiry is sent to our counterpart in overseas and production/supply of specific value is ensured considering future requirements in terms of quantities.”
The technical centre at Deki is responsible for carrying out R&D activities with a target of 30 per centt share of total T/O for new products. For the first three years, from the conception, any product is considered as new product. “Deki has been consistently introducing new types of film capacitors in the market to meet the needs of the customers. Lighting being the main area of focus, Deki has recently introduced PES series and patented PSH series. PES (polyester extra strength) is a unique six film design, which helps to achieve better minimum breakdown with similar or less size of capacitors. PSH (polyester self healing) is a unique patented design, having inductive construction with self healing property, especially developed for high wattage CFLs and HF ballast. An ideal capacitor to replace MPP/MPP 15mm pitch capacitors with footprint of 5.0mm and 7.5mm pitch,” explains Sharma.
Miniaturisation is a trend, in cases where size is of importance, with aluminium electrolytic capacitors. Says Radhakrishnan, “Capacitors of size Ø3X5 mm are currently available in the electrolytic capacitors category. Rapid developments are also taking place through the introduction of low impedance/low ESR capacitors, versions with longer life of 8000 to 10,000 hrs, capacitors with the heat range of +1250C for automotive applications, bipolarised electrolytic capacitors with a wide temperature range and high ripple long-life snap-in type capacitors.
Choosing a capacitor
There are several brands of capacitors that are currently available in the market. Capacitors are available from both indigenous and overseas sources. “Dimensional details, body colour and visual parameters match those of the leading brands, and it’s difficult for a buyer to differentiate between the spurious capacitors and the original brands. Hence, a buyer has to exercise caution by choosing capacitors of reputed brands,” says Radhakrishnan.
According to Singh, choosing a capacitor that meets a customer’s electrical, manufacturing and environmental requirements is difficult. “The size of a capacitor is primarily dependent on the product’s capacitance and working voltage, and the particular dielectric material used in the capacitor. Buyers should be aware of these specifications,” he says.
Says Haneef, “Customers usually look for consistency in supply, a low price and getting all parts from one source. Instead, a buyer should look for good quality capacitors based on the application the capacitors are required for.” Haneef also suggests that buyers should go for a compact size and for durability. “Our company is ISO 9001:2008 certified and our products are manufactured as per international standards. Any changes in design are communicated to our dealers and customers from time to time,” he says.
Sikka points out that capacitors are categorised as per their application. For example, super heavy duty capacitors are used in rolling mills, stone crushers, cement industry, sugar mills, paper industry, IT/software industry, oil fields, etc. “These industries have harmonics levels of more than 20-25 per cent, so super heavy duty capacitors should be used. Industries where the harmonics level is more than 15-20 per cent would prefer heavy duty capacitors. Normal duty capacitors should be used in small scale industries, to manufacture consumer goods and in other industries where the harmonics level is below 15 per cent,” he adds.
Sikka adds that buyers should use good quality capacitors that will ensure a better life to the end products. “Normally, the pay back period of power capacitors is six months to one year, so the customer should go in for better quality instead of the lower priced capacitor,” he says.
Jain is, however, concerned over the low awareness levels among consumers. “Capacitors face competition from cheap and affordable substitute technologies, which consumers are not aware of. They should do some research and learn about the latest technologies to avail the best in the market,” he explains.
Sharma puts it interestingly: “Consumers should analyse the supplier on quality, cost, delivery and service (QCDS). Deki offers good quality capacitors with internationally competitive prices and have an edge on imported capacitors, when it comes to logistics and service. Sharma urges that the customer should analyse the supplier on total cost of ownership perspective keeping QCDS in mind. He further advises that customer’s R&D should involve Deki’s technical centre from the designing stage whilst selecting a film capacitor with quality requirement and life expectation. This will certainly give Deki an opportunity to advice the optimum design to the customers. “Most of Deki’s overseas customers are involving Deki’s technical centre for selection of a capacitor for any new application, resulting a win win situation for both,” adds Sharma.
Electrolytic capacitors, like other electronic components and devices, are prone to failure in case of wrong application in equipment and systems. “The mode of failure may be either by an open circuit or short circuit of the component. If a reverse voltage is applied to the capacitor, rapid heating due to internal chemical action may take place, resulting in high-pressure generation inside the capacitor. This may cause either the sealing bung to rupture or the pressure relief vent to operate. Under extreme conditions, explosion and fire could result since the oozing out electrolyte is combustible. Hence, the correct application will ensure optimum performance of the capacitors over their entire life span,” adds Radhakrishnan.
Indian vs. Chinese capacitors
India can match Chinese capacitors in terms of variety, quality and timely dispatches. However, the difference between Chinese and Indian products is simply the price. But this can be surmounted in the case of special varieties where the requirement is small. The ordinary bulk-ordered capacitor market is very price sensitive, and Indian manufacturers may not be able to compete with the Chinese. However, in niche markets, India can always succeed.
Further, Chinese manufacturers get all raw materials produced locally (in China), but in case of India, manufacturers have to import these from China, Taiwan, Korea and Europe. This adds to the cost. We, thus, need a strong local manufacturing base for the main raw materials. Plastic film is still imported in bulk to cater to the metallised film capacitor manufacturers. If this issue is addressed, Indian manufacturers can compete globally. Government can support investors to put up plants for the manufacture of raw materials. The SME sector can be allowed to pass on the excise duty to the required customers who are availing exemption based on sales turnover. This will avoid the anomaly existing today.
Applications of capacitors
Capacitors can be used in a variety of different ways in electronics circuits. Although their mode of operation remains exactly the same, they can be used to provide a variety of different circuit functions:
- Coupling capacitors: These allow AC signals to pass from one section of a circuit to another while blocking any DC components.
- Decoupling capacitors: Remove any AC signals that may be on a DC bias point or power rail.
- Smoothing capacitors: These are effectively the same as decoupling capacitors, but the term is normally used in conjunction with a power supply.
- A timing element: In this application a capacitor can be used with a resistor or inductor in a resonant or time dependent circuit. In this function the capacitor may appear in a filter, oscillator tuned circuit, or in a timing element for a circuit
- Capacitors are also used for power factor correction in industries, hospitals, hotels and other commercial establishments that have three phase connections
- Motor run capacitors are required for equipment like air conditioners, washing machines, air coolers, fans and lighting
- Electrolytic capacitors are used in the electronic circuits of different electronic applications
- Screw terminals are used in industrial electronics—in converters, UPS and SMPS systems
- Snap-in is used in industrial electronics, consumer electronics, telecommunications, control engineering, automotive electronics and entertainment electronics.
Other applications are:
- Surge arresting
- Motor starting
- Signal processing
- DC blocking capacitor
- Capacitors as a discharge unit
- Snubber capacitors
Segments that propel growth
Ongoing technological advancements and increasing volume requirements for capacitors in industrial, medical, telecommunications, automotive, aerospace and defence markets is likely to propel sales in the capacitors market. Other factors that drive growth include:
- Demand for mobility in both computing and communications
- Rising capital expenditure to support migration from GSM to GPRS and 3G
- Stronger than envisaged growth in the mobile handset market
- Increasing demand for voice over IP
- Continued demand for broadband
- A rapid acceleration in demand for digital consumer products including digitalcameras, advanced TV and DVD
Segments that create demand for capacitors are:
- Consumer electronics
- Industrial electronics
- Home entertainment
- Medical electronics
- Communication electronics
- Professional electronics
- Military applications
Types of capacitors
- Metallised film capacitors: Use a very thin aluminium foil, interlinked with a very thin plastic dielectric. For high voltage capacitors, polyester and polystyrene plastic materials are used. Dielectric strength is the ability of an inductor to resist the flow of current when voltage is applied across it.
- Ceramic capacitors: These are used when small values of capacitance and large values of linkage current are acceptable. Ceramic capacitors are inexpensive and consist of a thin ceramic dielectric that is metallised on each side and coated with a thick protective layer usually applied by dipping the component in an electrified protective material. Both plastic film and ceramic capacitors are available in ranges of 10pf to1uf.
- Electrolytic capacitors: These are high voltage capacitors that give a high value of capacitance in a small component at the expense of wide tolerance in the marked value (typically between -25 to 50 per cent) and the necessity of connecting the capacitor so that one terminal is always positive. The most commonly used types of electrolytic capacitors are aluminium electrolytic capacitors. Electrolytic capacitors must not be subjected to voltages in the wrong direction.
- Variable capacitors: These capacitors are variable in values. Either air or thin mica sheets are used as the dielectric. There are two types of variable capacitors—the rotary and compression type.
There are many different capacitor types that can be bought and used in electronics circuits.
- Ceramic: As the name indicates, ceramic capacitors use a ceramic dielectric. There are different types of dielectrics; some are used for low values of capacitance, while others are used for higher capacitance levels.
- Electrolytic: This is the most popular type for values greater than 1 microfarad, with one of the highest levels of capacitance for a given volume.
- Plastic film capacitors: There are different types of plastic film capacitors. Polycarbonate, polyester and polystyrene are some of the most common. Each has its own properties, required in specific applications. Their values may range anywhere from several picofarads to a few microfarads, depending upon the actual type.
- Silver mica: Silver mica capacitors are manufactured by plating silver electrodes directly on to the mica film dielectric.
- Tantalum: Ordinary aluminium electrolytic capacitors are rather large and are used for many purposes. In applications where size is of importance, tantalum capacitors are used.
|Name of manu-facturer/distributor||Types of products||Price range||Important features||Contact details|
Aluminium electrolytic caps for power supplies & conversion (SMPS/UPS/battery chargers/solar inverters), wide range of box type film caps
Varies from product to product
Compatibility with international standards & price competitiveness
Ceramic disc capacitors (low voltage, high voltage and extra high voltage up to 70 kv DC); metal oxide variators; piezoelectric buzzers; telephone ringers
Varies from product to product, as per the required specifications in the manufacturing and price range
Custom designed products and competitive prices
C M Haneef, vice president;
Varies from product to product and customer specification
Good quality capacitors with competitive prices and short lead times
Vinod Sharma, managing director,
Havells India Ltd
Normal duty capacitor (Master and Hercules);
heavy duty capacitor (Master Plus and Phantom); super heavy duty capacitor (Champion)
Rs 115 & Rs 95
for 1 KVAr;
Rs 185 & 155
for 1 K Var; Rs 237 for 1 K Var
Longer life, low losses and burst proof
Havells India Ltd, QRG Towers, 2D, Sector 126, Noida 201304, Email: firstname.lastname@example.org
Keltron Component Complex Ltd
Aluminium electrolytic capacitors, motor run capacitors, MPP-SH type,
Ph: 0497-2780831 to 2780834, Fax: 0497-2781055, E-mail: email@example.com
Sumitron Exports Pvt Ltd
Aluminium electrolytic capacitors, tantalum capacitors, film capacitors, ceramic capacitors
Excellent quality of international standards; high precision
Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine