Types of Industrial Capacitors and Their Practical Applications

Capacitors of all sizes are found in everyday products like pocket calculators and flat-screen TVs. They're also used in air conditioning equipment, high-voltage substations and arc furnaces for metallurgical factories. While designs for fuses, circuit breakers, transformers and switches have remained relatively static, capacitors have improved steadily in the new millennium. Engineering and manufacturing advances have created a variety of high-performance capacitors that can withstand extreme heat and demanding conditions. Thanks to these features, capacitors are used in many high-tech and emerging industries.

Dielectric Materials in Industrial Capacitors

According to the Electronic Components Industry Association, 55 percent of capacitors manufactured in 2015 used ceramic as the primary dielectric. Aluminum and tantalum had almost equal market shares of 19 and 17 percent respectively. Both metals are extremely resistant to corrosion, chemicals and oxidation thanks to a self-generated oxide layer. This film is critical because it acts as the dielectric insulation between the metal plates. In the high-performance sector, capacitors with paper or film dielectric layers represented just 8 percent of sales although they are commonly found in printed circuit boards, capacitor-resistor snubber circuits, high-surge pulse applications, non-critical filters and interference suppression systems.

Industry Trends

Many new proprietary designs feature value-added passive components. Manufacturers are pursuing opportunities to develop a wider range of high-performance products because they have better average selling prices. High-performance capacitors for the automotive and petroleum industries are designed to withstand temperature extremes. Additionally, new products have greater capacitance, longer life expectancies and smaller case sizes.

Demand for individually packaged, also called discrete, capacitors is increasing significantly in the Asia-Pacific region as well as Latin America and the United States. The global market for discrete capacitors is expected to top $25 billion annually by 2020.

Specialty Capacitors

According to California-based Global Industry Analysts, computers, consumer appliances and telecommunications equipment are the largest users of discrete capacitors. On this side, growth is coming from developing nations. However, automotive, military and industrial applications are increasing worldwide sales. Top subsectors are industrial automation, intelligent automotive components and mobile communications networks. Potential applications are expanding thanks to tantalum capacitors that are used in pulse-discharge circuits.

Today, 45 percent of value-added capacitors are made from high-voltage ceramic. About 25 percent of specialty configurations are used in under-the-hood automotive applications. Ultracapacitors, also called supercapacitors, are gaining popularity in this sector as well. The high cost and large size previously limited these capacitors to specialized military applications although they can hold 10 to 100 times more energy. Ultracapacitors are suited for high-demand, short-use applications. Because they support DC exclusively, they are useful in the automotive industry where critical and auxiliary components are powered by batteries.

Automotive and Transportation Industries

Demand for high-temperature capacitors has increased in the automotive industry. Engine, transmission and regenerative brake applications are the most common. In large industrial equipment, high-performance capacitors are replacing mechanical and hydraulic systems. Capacitors with tantalum and ceramic dielectrics are especially valuable when equipment will be subjected to extreme temperatures. These components are found in all types of electric transportation systems, including buses, electric trains, subway cars and rail switches. Capacitors and batteries are used in hybrid cars to regulate power usage and storage. These products require extensive quality tests, such as mechanical shock, vibration and terminal strength, to ensure the safety of passengers and operators.

Capacitors in the Energy Sector

The market for capacitors is often influenced by conditions in the gas and oil industry. High-temperature capacitors and components are required for down-hole drilling. Products that meet these demanding specifications and have large capacitance values have been developed especially for global energy clients. Recent engineering advances led to the development of solid electrolytic and wet tantalum capacitors that can withstand temperatures above 200 degrees Celsius. Many of these high-performance capacitors are sold to companies that manufacture drilling equipment. Capacitors are probably best known for regulating voltages in the electric grid. Now, they are gaining market share in wind farms and solar installations. Marx generators use a bank of capacitors wired in series to test high-voltage equipment.

Laser Machinery

Rapid-discharge capacitors, such as those used in flash bulbs, are useful in powering industrial lasers. While some capacitors are designed to hold electrical energy, these can release the stored voltage in a fraction of a second. Rapid-pulse capacitors can produce more than a thousand pulses per second. This creates continuous waveforms for industrial C02 lasers. These diodes are especially useful in cutting, welding and processing durable materials, including metals and diamonds. Pulse capacitors are used for X-rays, food sterilization, missiles, radar and ultrasonics.

Other Industrial Applications

Today, 69 percent of capacitors are used in power supplies, high-voltage substations, inverters, drives and motors. These applications include HVAC equipment, photovoltaic inverters and single-phase or three-phase motors. The following applications each represent less than 6 percent of all end-use capacitors and a cumulative 29 percent.

• Voltage correction
• Defense electronics
• Television equipment
• Telecom networks
• Gas and oil machinery
• Medical equipment
• Microwave products
• Lighting ballasts
• Semiconductors

One of the most interesting changes is the shift between conventional and high-performance options. For example, polyethylene film capacitors hold half of the global market share in conventional options, but they are the least common dielectric in specialty products where tantalum and ceramic are preferred for their exceptional heat resistance. Harmonic filtering capacitors continue to regulate the output of variable frequency drives, data centers and uninterruptable power supplies.

Because capacitors are widely used in industrial and consumer products, there are many opportunities for growth. There's also increasing demand for capacitor winding machines and related equipment to supply the market.