Power Supply Units Abbreviations and Symbols

The rating plate of an Extra Low Voltage Power Supply Unit (ELVPSU) shows various symbols and abbreviations representing ratings, class, insulation, polarity and other electrical safety and EMC compliance details.

DC Adaptor Polarity Symbols

The polarity symbol on the rating plate of an AC to DC power supply indicates if the centre (or tip) of the output plug is positive (+) or negative (-). It is important to use a power supply having the correct polarity for the host device. Reverse polarity may result in malfunctioning or damaged equipment.

plug pack center positive symbol circuit diagram polarity power transformer DC adaptor

Centre Positive.

Indicates that the centre (tip) of the output plug is Positive (+) and the barrel of the output plug is Negative (-).

Centre Negative.

Indicates that the centre (tip) of the output plug is Negative (-) and the barrel of the output plug is Positive (+).

ABBREVIATIONS

The following abbreviations used in conjunction with a numeric value, are used to define nominated electrical characteristics of a power supply unit.

V	volts	Hz	hertz
A	amperes	PRI	input
mA	miliamperes	SEC	output
VA	volt amperes	DC	direct current
VAC	volts AC	AC	alternating current
W	watts	~	single phase (AC)

OTHER SYMBOLS

These symbols are used to define the type of construction and safety and/or fail-safe characteristics of a power supply unit

symbol circuit diagram power adaptor transformer regulator DC

Direct current

symbol circuit power plug class 2 adaptor double insulated transformer DC AC regulated plugpack

Class II construction.

symbol circuit diagram powerplug fuse adaptor transformer powerpack AC DC protection

Fuse-link

circuit symbol powerplug powerpack adaptor transformer earth protection protective

Frame or core terminal

Protective earth

Isolating transformer

powerplug powerpack adaptor transformer circuit symbol DC AC safety isolating

Safety isolating transformer

powerplug powerpack transformer adaptor fail safe DC AC

Fail-safe transformer

powerplug powerpack transformer adaptor circuit symbol AC DC non-shorting circuit inherent non-inherent protection

Non-short-circuit transformer.

Has an associated external protective device.

powerplug powerpack transformer adaptor circuit symbol AC DC short circuit inherent non-inherent protection

Short-circuit-proof transformer.

There are two types. An inherent type is s/c proof provided that the temperature rise does not exceed the specified limit. A non-inherent type is equipped with an external protective device.

powerplug power pack circuit symbol transformer adaptor AC DC isolating safety fail-safe non-shorting short shorting

Fail-safe transformer

The non-short circuit-proof transformer symbol or the short-circuit-proof transformer symbol can be combined with either an Isolating transformer symbol or with a Safety isolating transformer symbol to produce a composite symbol. In this example, the Short-circuit-proof symbol is used in conjunction with the Safety isolating transformer symbol.

C-Tick

A C-Tick mark appears on products which are required to comply with Australian electromagnetic compatibility requirements and with Australian radiocommunications standards. It signifies that the product may be legally sold in Australia.

RCM comply compliance Australia Australian Austest Austel ACA radiocommunications standard standards compatability

Regulatory Compliance Mark

The RCM may be used as an alternative marking to show compliance with Electrical Safety and EMC standards