Booster (electric power)
A Booster was a motor-generator (MG) set used for voltage regulation in direct current (DC) electrical power circuits. The development of alternating current and solid-state devices has rendered it obsolete. Boosters were made in various different configurations to suit different applications.
In the days of direct current mains, voltage drop along the line was a problem so line boosters were used to correct it. Suppose that the mains voltage was 110 V. Houses near the power station would receive 110 volts but those remote from the power station might receive only 100 V so a line booster would be inserted at an appropriate point to "boost" the voltage. It consisted of a motor, connected in parallel with the mains, driving a generator, in series with the mains. The motor ran at the depleted mains voltage of 100 V and the generator added another 10 V to restore the voltage to 110 V. This was an inefficient system and was made obsolete by the development of alternating current mains, which allowed for high-voltage distribution and voltage regulation by transformers.
Again in the days of direct current mains, power stations often had large lead-acid batteries for load balancing. These supplemented the steam-powered generators during peak periods and were re-charged off-peak. Sometimes one cell in the battery would become "sick" (faulty, reduced capacity) and a "milking booster" would be used to give it an additional charge and restore it to health. The milking booster was so-called because it "milked" the healthy cells in the battery to give an extra charge to the faulty one. The motor side of the booster was connected across the whole battery but the generator side was connected only across the faulty cell. During discharge periods the booster supplemented the output of the faulty cell .
Before solid-state technology became available, reversible boosters were sometimes used for speed control in DC electric locomotives. To avoid confusion, it should be explained that it is the electrical output of the booster that is reversible, not the direction of rotation.
The motor of the MG set was connected in parallel with the supply, usually at 600 volts, and was mechanically coupled, via a shaft with a heavy flywheel, to the generator. The generator was connected in series with the supply and the traction motors, and its output could be varied between +600 volts, through zero, to -600 volts by adjusting switches and resistors in the field circuit. This allowed the generator voltage to either oppose, or supplement, the line voltage. The net output voltage could therefore be varied smoothly between zero and 1,200 volts as follows:
- Generator producing maximum opposing voltage, net output zero volts
- Generator producing zero volts, net output 600 volts
- Generator producing maximum supplementary voltage, net output 1,200 volts
To match the 1,200 volt output, the locomotive would have three 400 volt traction motors connected in series . Later locomotives had two 600 volt motors in series.
When the locomotive was working at full power, half the energy came through the MG set and the other half came directly from the supply. This meant that the power rating of the MG set needed to be only half the rating of the traction motors. Thus there was a saving in weight and cost compared to the Ward Leonard system, in which the MG set had to be equal in power rating to the traction motors.
If the power supply to the locomotive was interrupted (e.g. because of a gap in the third rail at a junction) the flywheel would power the MG set for a short period to bridge the gap. During this period, the motor of the MG set would temporarily run as a generator. It was this system that was used in the design of British Rail classes 70, 71 and 74 (Class 73 does not utilise booster equipment).
Some types of London Underground stock (e.g. London Underground O Stock) were fitted with Metadynes . These were four-brush electrical machines which differed from the reversible boosters described above.
- ^ Elliott, T. C., Electric Accumulator Manual, George Newnes Ltd, London, 1948, page 29
- ^ Cooper, B. K., Electric Trains and Locomotives, Leonard Hill Ltd, London, 1954, pp 35–38
- ^ Cooper, B. K., Electric Trains and Locomotives, Leonard Hill Ltd, London, 1954, page 38
Electric motors Broad motor categories Conventional
Unusual electric motors Motor
Wikimedia Foundation. 2010.
Look at other dictionaries:
Booster — may refer to:In science and technology: * Booster (electric power), a motor generator set used for voltage regulation in direct current electrical power circuits * Booster dose, or booster shot, in medicine, a vaccination given after a previous… … Wikipedia
Electric motor — For other kinds of motors, see motor (disambiguation). For a railroad electric engine, see electric locomotive. Various electric motors. A 9 volt PP3 transistor battery is in the center foreground for size comparison. An electric motor converts… … Wikipedia
Electric generator — U.S. NRC image of a modern steam turbine generator In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge (usually carried by electrons) to flow… … Wikipedia
Power steering — helps drivers steer vehicles by augmenting steering effort of the steering wheel. It does this by adding controlled energy to the steering mechanism, so the driver needs to provide only modest effort regardless of conditions. In particular, power … Wikipedia
Booster Gold — This article is about the character. For the title he appears in, see Booster Gold (comic book). Booster Gold Michael Jon Carter as Booster Gold from Countdown to Infinite Crisis. Art by Ed Benes … Wikipedia
Brushless DC electric motor — A microprocessor controlled BLDC motor powering a micro remote controlled airplane. This external rotor motor weighs 5 grams, consumes approximately 11 watts (15 millihorsepower) and produces thrust of more than twice the weight of the plane … Wikipedia
Brushed DC electric motor — A brushed DC motor is an internally commutated electric motor designed to be run from a direct current power source. Contents 1 Simple two pole DC motor 2 The commutating plane 2.1 Compensation for stator field distortion … Wikipedia
Quadrature booster — A quadrature booster, also known as a phase shifting transformer or more simply a quad booster, is a specialised form of transformer used to control the flow of real power on three phase electricity transmission networks. For an alternating… … Wikipedia
General Electric CF6 — The General Electric TF39 and CF6 are a family of high bypass turbofan engines. Originally developed as the TF39 to power the C 5 Galaxy, they were the first high power high bypass jet engines available, and went on to power a wide variety of… … Wikipedia
Villains in Power Rangers in Space — The fictional villains of the Power Rangers universe that appeared in the television series Power Rangers in Space are aliens, and members of an alliance under the command of Dark Specter. This included many villains from previous seasons of… … Wikipedia