{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapt 1-0 Reading_Applications-PE

Chapt 1-0 Reading_Applications-PE - Electronic ballasts...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Electronic ballasts: , also called solid-state ballasts, are those power electronic converters used to supply discharge lamps. The modern electronic ballasts with the development of low cost power MOSFETs allow to supply fluorescent lamps at frequencies of several kilohertz and increasing lamp luminous efficacy ['efik si] ə by operating at these high frequencies. The main benefits of electronic ballasts are the increase in the lamp and ballast overall efficiency, increase in lamp life, reduction of ballast size and weight, and improve-ment in lighting quality. UPS: Power distortions such as power interruptions, voltage sags and swells, voltage spikes, and voltage harmonics can cause severe impacts on sensitive loads in the electrical systems. Uninterruptible power supply (UPS) systems are used to provide uninterrupted, reliable, and high quality power for these sensitive loads. Applications of UPS systems include medical facilities, life supporting systems, data storage and computer systems, emergency equipment, telecommunications, industrial processing, and on-line management systems . The UPS systems are especially required in places where power outages and fluctuations occur frequently. A UPS provides a backup power circuitry to supply vital systems when a power outage occurs. In situations where short time power fluctuations or disturbed voltage occur, a UPS provides constant power to keep the important loads running. During extended power failures, a UPS provides backup power to keep the systems running long enough so that they can be gracefully powered down. Most of the UPS systems also suppress line transients and harmonic disturbances. Generally, an ideal UPS should be able to simultaneously deliver uninterrupted power and provide the necessary power conditioning for the particular power application. Therefore, an ideal UPS should have the following features: regulated sinusoidal output voltage with low total harmonic distortion (THD) independent from the changes in the input voltage or in the load, on-line operation that mean zero transition time from normal to back-up mode and vice versa, low THD sinusoidal input current and unity power factor, high reliability, high efficiency, low EMI and acoustic noise, electric isolation, low maintenance, low cost, weight, and size. Obviously, there is not a single configuration that can provide all of these features. Different configurations of UPS systems emphasize on some of the features mentioned above. Classifications of UPS systems are described in Section 24.2 Off-line UPS: Standby-UPS This configuration of UPS system is also known as “off-line UPS” or “line-preferred UPS” . It consists of an AC/DC converter, a battery bank, a DC/AC inverter, and a static switch . A passive low pass filter may also be used at the output of the UPS or inverter to remove the switching frequency from the output voltage. The static switch is on during 1
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
the normal mode of operation. Therefore, load is supplied from the AC line directly without any power conditioning. At the same time, the AC/DC rectifier charges the
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern