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Albacom - Microwave & Power Supplies glossary Category: Electronics and Engineering > Microwave, power supplies Date & country: 11/12/2007, UK Words: 150

Rated output current
The maximum continuous load current a power supply is designed to provide

Rated power
The maximum continuous output (or input) power a power converter is designed to supply

Rated supply voltage
The range of input supply over which a power converter is designed to operate

Ratings
Specified values delineating the absolute maximum capabilities of a power converter

Rectifier
Circuit using semiconductor diodes to change an alternating (AC) current into a direct (DC) current

Regulation
1. The control of power converter output voltage(s). 2. Changes in output voltage due to changes in input supply or load. See Line regulation, Load regulation

Remote sensing
A technique for monitoring the output voltage of a power converter at the load rather than at the output terminals. Improves regulation by compensating for voltage drops in the wiring between the power converter and the load

Renewable energy sources
Prime power sources generated using environmentally acceptable processes e.g wind turbines, solar cell arrays, wave power generators, fuel cells etc

Resonant converter
A switching converter whose operating frequency is not fixed but is controlled by the natural zero-crossings of voltage or current taking place in its power circuit. The technique eliminates much of the switching loss associated with fixed-frequency converters by enabling switching at either near-zero voltage or near-zero current

RFI (Radio Frequency Interference)
Another term for EMI

Ripple
Any periodic AC component present in the output of a DC power supply which is related either to the input AC supply or to switching frequencies within the power supply itself. See Noise

Saturation
This is the phenomena in an amplifier where for a further increase in input signal there is no increase in output signal.

Semi regulated output
An output from a multiple output power supply that is not regulated by closed loop control although it is subject to the effect of closed loop control acting on another output

Series regulator
A linear regulator in which the active control element (transistor) is connected in series with the load. Regulation is achieved by the control element sustaining a voltage whilst carrying the load current and results in dissipation

Short circuit
A direct connection that provides an almost zero resistance path for current

Short circuit protection
Circuit feature that limits the output current of a power supply to prevent damage when loaded with a short circuit

Shunt regulator
A linear regulator in which the active control element (transistor) is in parallel with the load. Regulation is achieved by the control element sinking a current whilst carrying the load voltage and results in dissipation

Slow wave Structure
A microwave circuit along which an electromagnetic wave is propagating. The circuit is constructed so that the velocity of the electromagnetic wave is near synchronous with the beam velocity. The electron beam and the RF wave interact to transfer energy from the electron beam to the RF wave to produce amplification.

Small Signal Gain
The power Gain in decibels provided by an amplifier when the output power is well below Saturation. This is normally at least 10 dB below saturation.

Soft-start
Circuit features which gradually increase the power output from a converter when it is powered-up. Minimises stresses on the power circuit components by eliminating uncontrolled voltage or current surges.

Solenoid
A cylindrical coil consisting of a multiple winding. It is commonly used as an electromagnet to assist in the focussing of an electron beam.

Space Charge
The electric charge carried by a cloud or stream of electrons or ions in a vacuum or a region of low gas pressure, when the net charge density is sufficient to produce local changes in the potential distribution.

Stability
The change in output voltage of a power supply over a specific period of time, following a warm up period, with all other operating parameters held constant

Standby Heater Voltage
To enable a tube to be more rapidly, ready for use the heater voltage may be left applied, but at a lower than usual value. This is the “standby heater voltage�.

Standing Wave Ratio (SWR)
Any transmission line, unless terminated by its characteristic impedance, will exhibit a superposition of standing and progressive waves. The standing wave ratio is defined as the ratio of the maximum amplitude of voltage to the minimum amplitude of voltage measured along the path of the waves.

Static inverter
A power converter designed specifically to produce an AC output meeting the specifications for utility line supplies e.g 240V 50Hz in Europe or 110V 60Hz in the USA. Input supplies normally derived from renewable energy sources

Switch-mode converter
Another term for switching converter

Switching converter
Generic term for any form of power converter which achieves power transfer and regulation using semiconductor switches alternating between full conduction and full blocking, normally at high frequency. The technique eliminates much of the (dissipative) loss associated with linear regulation and enables physical shrinkage of transformers and filter …

Switching frequency
The rate at which a switching power converter or regulator operates its switches

Switching regulator
A regulator utilising semiconductor switches which open and close as necessary to regulate power output and thus control the voltage across a load

Temperature coefficient
The sensitivity of output voltage to changes in the temperature of a power converter

Temperature range
The range of ambient (or mounting surface) temperatures over which a power converter will meet its specifications

Thermal protection
A protective feature that shuts down a power supply if its internal temperature exceeds a predetermined limit

Thermionic Cathode
This is a source of electrons which are emitted from a hot surface. The work function of the surface is lowered by the use of a coating or impregnant usually of barium. Conventional Oxide cathodes have been replaced by Dispenser cathodes which contain a mixture of barium-calcium aluminates within a porous structure. Emission from this type of cathode can be enhanced by the addition of coatings such as Osmium. These cathodes are known as B-type and M-type.

Topology
The classification of circuit configurations of power converters into clearly identifiable and characteristic types, usually based on the way the power circuit switching semiconductors and magnetic components are connected. Examples of circuit topologies are Flyback, Push-Pull, Half-Bridge etc

Tracking
A specified relationship between the outputs of a multiple-output power converter where any changes due to line, load, temperature (or other parameters) are proportional across all outputs

Transformer
The key magnetic component in most power converters. Consists of a magnetic “core� wound with 2 or more “windings�. An AC voltage applied to the “primary� (input) winding will cause an alternating flux swing in the core which will induce AC voltages in the “secondary� (output) windings, all in proportion to the number of turns in the respective win…

Transient
A temporary and brief change in a given parameter. Typically associated with input voltage or output loading parameters

Transient recovery time
The time interval between a step change in the loading or supply conditions for a power converter to the time when the outputs return to within specification

Transient response
Specifications defining a power converter`s behaviour during and following a transient. See Transient recovery time, Overshoot, Undershoot

Travelling Wave Tube
A linear beam device which uses a Slow-Wave Structure to provide Microwave or RF amplification.

Travelling Wave Tube Amplifier
The combination of a travelling wave tube and a power supply which provides the necessary electrode voltages and control and monitoring signals. Other components which might include a Lineariser, Gain Equaliser, Output Monitor and Input Monitor could form part of the amplifier.

Undershoot
The amount by which an output falls short of its intended value at initial power-up or in response to a step change in load or input voltage

Universal input
Term describing a power converter designed to operate from any available AC mains supply, worldwide, without user adjustment or settings

UPS (Uninterruptible Power Supply)
A power converter designed to supply output power in the event of temporary loss of AC line power. Usually configured as battery-backed off-line converters with integrated battery charging circuits and automatic changeover between off-line and battery-backed operation

Voltage mode control
Power converter regulation technique based only on monitoring and control of output voltage

Voltage-fed
Term applied to power circuits where the power being switched is at a constant voltage, such as across the terminals of a capacitor

VSWR
See Standing Wave Ratio.

Zero current switching (ZCS)
The synchronising of the operation of semiconductor switches in (resonant) power converters with the natural zero-crossing of the current flowing in the converter`s power circuit. Results in near-lossless switching, permitting increases in switching frequency required to enable reduction in transformer and filter component sizes. This facilitates t…

Zero-voltage switching (ZVS)
Similar to ZCS, but using the voltage zero-crossings in the power circuit to synchronise the switches