* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 11 – Power Conditioners and UPS 1
Immunity-aware programming wikipedia , lookup
Standby power wikipedia , lookup
Wireless power transfer wikipedia , lookup
Solar micro-inverter wikipedia , lookup
Power factor wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Electrification wikipedia , lookup
Electrical substation wikipedia , lookup
Electric power system wikipedia , lookup
Power over Ethernet wikipedia , lookup
Voltage regulator wikipedia , lookup
Audio power wikipedia , lookup
Power MOSFET wikipedia , lookup
Stray voltage wikipedia , lookup
Three-phase electric power wikipedia , lookup
Opto-isolator wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Surge protector wikipedia , lookup
Distribution management system wikipedia , lookup
History of electric power transmission wikipedia , lookup
Amtrak's 25 Hz traction power system wikipedia , lookup
Buck converter wikipedia , lookup
Power engineering wikipedia , lookup
Power inverter wikipedia , lookup
Power supply wikipedia , lookup
Voltage optimisation wikipedia , lookup
Uninterruptible power supply wikipedia , lookup
Alternating current wikipedia , lookup
POWER CONDITIONERS AND UNINTERRUPTABLE POWER SUPPLIES (UPS) Part 1 POWER CONDITIONERS: Power conditioners provide an effective way of suppressing some or all of the electrical disturbances other than power outages and frequency deviations from 60 Hz. Some of these power conditioners are listed below: - - METAL-OXIDE VARISTORS – provide protection against voltage spikes ELECTROMAGNETIC INTERFERENCE FILTERS – help to prevent the effect of chopped waveform on the equipment as well as to prevent the equipment from conducting high-frequency noise into the utility grid ISOLATION TRANSFORMERS WITH ELECTROSTATIC SHIELDS - provide galvanic isolation and filter voltage spikes FERRORESONANT TRANSFORMERS – provide voltage regulation as well as filtering of voltage spikes; also partially effective in filtering noise LINEAR CONDITIONERS – used in many sensitive applications to supply clean power For voltage regulation, an electronic tap changing scheme using triacs as shown below can be used. In this case triacs are used to replace mechanical contacts and they also allow current flow in both directions. UNINTERRUPTABLE POWER SUPPLIES (UPS): For supplying very critical loads such as computers controlling important processes, some medical equipment and the like, it may be necessary to use UPS. UPS provide protection against power disturbances as well as voltage regulation during power line voltage sags and swells. They are also excellent in terms of suppressing incoming line transient 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: 1. Regulated sinusoidal output voltage with low total harmonic distortion (THD) and independent from the changes in the input voltage or load 2. Zero transition time from normal to back-up mode and vice versa 3. Low THD sinusoidal input current and unity power factor 4. High reliability 5. High efficiency 6. Low EMI and acoustic noise 7. Electric isolation 8. Low maintenance 9. 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 features mentioned above. BASIC BLOCK DIAGRAM OF UPS: RECTIFIER – is used for converting single-phase or three-phase ac input into dc, which supplies power to the inverter as well as to the battery to keep it charged; in the normal mode of operation, the power to the inverter is provided by the rectifier. Rectifier arrangements: a. In a conventional arrangement shown below, a phase-controlled rectifier is used b. It is also possible to use a diode rectifier bridge in cascade with a step-down dc-dc converter as shown below c. When an electrical isolation from the mains is required, it is possible to use a dc-dc converter with a high frequency isolation transformer as shown below d. Another rectifier arrangement is shown below, where the bulk of the power supplied to the inverter flows through the diode bridge and only the power required for charging of the battery bank flows through a single-phase phase controlled thyristor rectifier. The voltage Vcharge can be controlled in magnitude and polarity for proper charging of the battery bank. Thyristor T1 normally remains off; it is turned on in the event of a power outage. (As a classroom activity next meeting, you will be divided into 5 groups. 1. Each group is assigned one power conditioner topic to research on. 2. Each group should submit a brief written report to the instructor about the topic assigned, and at the same time, this written report will serve as handouts to your classmates during the time your group will deliver your report to the rest of the class. 3. Your group’s written report will serve as your assignment #1 for midterm and will be graded according to the amount of information you have researched and according to how well you have organized the information about your topic. 4. Your group’s oral report will serve as your quiz #1 for midterm and will be graded according to your visual aides, mastery, and delivery.)