Glossary


NEED HELP WITH TECHNICAL TERMS AND ACRONYMS?
See below for the special

AC: (Alternating Current) Voltage or current which is periodically changing polarity

AC-DC Converter: Converts an alternating current power supply eg: 230V mains into one or several DC voltages as required by particular electronic circuits or in Powerstax's case mainly for the charging of battery operated equipment.

Ambient temperature: The still-air temperature of the immediate environment measured a minimum of 100mm from the power supply

Amps: (Amperes) Unit of measurement of electromotive current (A).

Basic Insulation: According to international safety standards (eg UL1950, EN60950) basic insulation provides basic protection against electric shock. In contrast, operational insulation is needed for the correct operation of the equipment, but does not protect against electric shock. Quite frequently, safety standards call for basic insulation between secondary circuits.

Breakdown voltage: See: Isolation

Bridge: Rectifier circuit incorporating four diodes (full-bridge) or two diodes (half-bridge). Converter or chopper section of switching power supplies incorporating four transistors (full-bridge) or two transistors (half-bridge).

Brownout: Condition during peak usage periods when electric utilities reduce their nominal line voltage by 10% to 15%.

Brownout protection: The ability of a power supply to continue operating within specification through the duration of a brownout.

Burn In:The period directly following the very first turn-on of a given power supply. It is characterized by a relatively high and declining failure rate.

Bus: The system of conductors (wire, cable, copper bars, etc.) used to transport power from the power supply to the load. A communications structure used to control various instruments and subsystems.

Busbar: A low impedance conductor which feeds power to various circuits in, for example, an equipment room or within an equipment rack. In the telecommunications industry the busbar voltage is often at a standardised 48V, requiring dc-dc converters to convert the busbar voltage to such voltages as are used by the electronics circuits it is supplying

CB-report: Document necessary for the mutual recognition of approvals between different national test norms.

CEE (International Commission on Rules for the Approval of Electrical Equipment): A regional, European safety agency. NB: the United States participates only as an observer.
Common-mode noise: The components of noise which is common to both the DC output and return lines with respect to input ground
Constant current: A power supply that regulates current level regardless of changes in load resistance.

Constant current limiting circuit: Current-limiting circuit that holds output current at some maximum value whenever an overload of any magnitude is experienced.

Constant voltage: A power supply that regulates voltage level regardless of changes in load resistance.

Convection: The transference of thermal energy in a gas or liquid by currents resulting from unequal temperatures.

Convection-cooled power supply is a PSU that is cooled from the natural motion of an air over the surfaces of its components.

Crowbar: A type of overvoltage protection circuit which rapidly places a low resistance shunt across the power supply output terminals if a predetermined voltage is exceeded.

CSA (Canadian Standards Association): An independent Canadian organization testing for public safety, similar to the function of Underwriters\92 Laboratories in the United States.

Current: Rate of transfer of electrical charge measured in amperes (A)

Current limiting circuit: A circuit designed to prevent overload of a constant-voltage power supply. It can take the form of constant, foldback or cycle-by-cycle current limiting.

Cycle-by-cycle current limiting circuit: Current-limiting circuit that immediately reduces output current to some minimum level whenever an overloaded of any magnitude is experienced.