Electronic Terms Glossary

AC
Current that flows in alternating directions between two points.  See also AMP, Current and DC.

AC/AC Adapter
Adapter that has an AC voltage input and an AC voltage output.

AC/DC Adapter
Adapter that has an AC voltage input and an DC voltage output.

Adapter
Electrical device that can take an AC voltage input and transform it into a different (or multiple) AC or DC voltage outputs.

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Ambient Temperature
The still-air temperature of the environment in which the adapter/transformer is operating. e.g., "room temperature."

AMP
Ampere...which is a measure of current.  Can be abbreviated by either "Amps", "A", or expressed as milliamps (mA).  See MilliAmps below..

CE
The European mark signifying compliance to low voltage and electromagnetic requirements..

Cord Set
A detachable means to supply electrical energy from the mains supply to an electrical device.  It has a connector at each end.

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Core Loss
This is the measure of power drawn by the input winding of a unit even when not in use (before load is applied).

Creepage
Creepage is the shortest distance between two conducting parts measured along the surface of the insulating material between them.

cUL
Underwriter's Laboratories has been granted the ability to test and approve electrical devices for use in Canada.  Units marked with the cUL mark have been tested by UL for use in Canada (and are fully recognized by Canada).

Current
The measure of current is expressed in AMPs.  Current can either flow consistently in one direction (DC current), or can reverse/ alternate directions (AC current).

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DC
Current that flows in the same direction between two points.  See also AMP, Current and AC.

Efficiency
Ratio of output power compared to input power.

Exciting Current
This is the measure of current drawn through the input winding of a unit even when not in use (before load is applied).  See also Core Loss.

Frequency
Measures the number of times that a flow of current changes direction in one second.  Expressed as Hertz (Hz).  Most North and South American locations operate on an input of 60Hz while most of Europe has a 50Hz input.

Hertz
Measure of frequency.  Usually expressed as Hz.  See Frequency.

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Hi-Pot (High Potential)
Used to confirm if the break-down voltage of a unit's internal insulation exceeds the minimum requirement.  Testing is done by applying high voltage between two isolated points such as primary to secondary, primary to ground, or secondary to ground for a very brief period.

Inherently Limited Transformer
Where the secondary short circuit condition after one minute does not exceed 8A for "Class 2" and 150V for "Class 3" (V is maximum no-load condition).  See also Not-Inherently Limited.

Impedance
Ratio of voltage to current expressed in ohms.  This measurement shows the resistance to the AC current flow.  Impedance between circuits must be matched in certain design situations.  See also OHM.

Input
This is the voltage and frequency applied to the primary of a unit.  For example, 120Volts 60Hz, 240Volts 50Hz, and so on.

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Inrush Current
Peak instantaneous input current drawn by a unit upon the initial application of input voltage.

Isolation
Where there electrical separation between the primary and secondary windings.  This safety feature helps eliminate the possibility of shock.

Leakage Current
The AC or DC current going from the input to output (and/or chassis) of an isolated power supply at a specified voltage.

MilliAmps
Measure of AMPs expressed as 1000 times Amps.  For example .5Amps would be 500mA (.5 x 1000).

MTBF
Mean Time Between Failure.

Nominal
Objective for a specified parameter...may not be the actual value measured.

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Not-Inherently Limited Transformer
Where an overcurrent protective device is either incorporated in the transformer or is required to be provided in the application.  Please refer to UL 1585, Table 27.3 (Current and Power Limitations) and Table 28.1 (Calibration Provisions) for further details.  See also Inherently Limited Transformer.

NRTL
Acronym for "Nationally Recognized Testing Laboratory."

OHM
The ratio of voltage to current is expressed in ohms.  This measurement shows the resistance to the AC current flow.  Impedance (or the number of measured ohms) between circuits must be matched in certain design situations.  See also Impedance and Resistance.

Open Circuit
When a circuit has been broken so that conducting components do not allow for the flow of current, the circuit is said to be open.  This condition can either be intentional (to provide protection), or unintentional (such as when a wire breaks).

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Output
The value in voltage and current at the output connections of a unit.

Overload Protection
Function of a power supply that automatically shuts down the supply in the event of reaching a predetermined excessive output current.

Overvoltage Protection
Function of a power supply that automatically shuts down the supply in the event of reaching a predetermined excessive voltage.

Parallel Circuit
Two or more parallel paths for current flow.  See also Series Circuit.

Power Supply Cord
A means of transmitting energy from the mains supply to an electrical device through a flexible electrical cable.  A power supply cord is permanently installed in the device being powered, as opposed to a cordset, which is detachable.

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Primary
A winding to which the input voltage is applied.  This winding then powers the secondary winding to generate an output voltage.

Rectification
Conversion of AC currents and voltages into DC currents and voltages.  Typical rectifications are: half-wave, full-wave and bridge.

Regulation (Line)
The percentage change in the output voltage due to a change in input voltage level.  This is usually a measurement of the output deviation as the input voltage is varied from low line to high line.

Regulation (Load)
The percentage change in output voltage due to a change in output loading.  This is usually a measurement of the output deviation as the loading is changed from no load to full load.

Resistance
This measurement shows the resistance to the AC current flow measured in ohms.   See also Impedance and OHM.

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Ripple
The magnitude of a unit's output AC voltage.

Secondary
Generates an output voltage and current when voltage is applied to the primary winding.

Series Circuit
A single, continuous path for current flow.  See also Parallel Circuit.

Short Circuit Protection
Function of a unit that limites the output current under short-circuit conditions so that the unit can avoid being damaged.

Temperature Rise
Measure of the heat generated by a unit at a given ambient temperature.  See also Ambient Temperature.

Thermal Protection
A feature that shuts down the unit in the event of excessive thermal   (temperature) conditions.  Usually accomplished with a one-shot or resettable   fuse.

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Universal Input
A feature of a power supply to accept a relatively wide range of input voltages.   The supply can either automatically adjust for the changed input or have a manual switch to do so.

VA
Volt Amperes (power).  Is the output voltage multiplied by the output current.   For instance, and ouput of 12V @ .5A = 6VA.

VAC
Statement of the voltage requirement.  For example an input of 120VAC is 120Volts at AC current.

VDC
Statement of the voltage requirement.  For example an output of 4VDC is 4Volts at DC current.

Volt
Measurement of voltage which is required to move a certain number of electrons from one point to another.  When the voltage moves in one direction it is DC volts and when it alternates direction, it is AC volts.

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Watt
Measurement of power determined by multiplying the output current by the output voltage.