NAME
STUDENT I.D
ETEC 4931 Electricity Systems Electrical Symbols and Terminology
Standard Drawing Symbols When we produce a drawing of an electrical circuit, layout, or arrangement we assume that the intended recipient will be able to understand what we have produced. In the case of drawings for contractors or sub contractors to use for construction or installation purposes, they not only have to understand the drawing, but must be able to use it to produce an accurately completed job. Many companies over the years have developed their own particular drawing styles, and in some cases their own particular symbols to represent contacts, relays, locations etc. Where these are used “in house” ie by their own staff, who know and understand the symbols used, this is fine and doesn’t create any problems. When these same drawings are sent to outside companies and individuals, the problems start to arise. In some instances the drawings will be well documented and the symbols used identifiable or identified in an accompanying legend. No problem, the drawings can be used. However additional time will be required to ensure accuracy, and if the drawings are to be updated and kept as “As Built” they may need to be re-drawn to match the recipient’s site standards. As you can imagine if everyone used his or her own individual system, that chaos would soon be the result. To avoid this, there are national and international standards set up for dr awing symbols and arrangements. For many years New Zealand adopted the British standard, and more recently with the advent of the CER agreement formed a joint Australian New Zealand standard, AS/NZS 1102, based on the international IEC 617 standard. The joint AS/NZS 1102 standard adopts the IEC 617 standard and adds additional local symbols (designated with an A in the standard) where the item in question was missing from the IEC list of symbols. Whenever you draw an electrical diagram you should use these standard symbols so all recipients can immediately follow your drawings. NO CONFUSION!
Site Plans When someone decides to build a house they will normally employ an architect to design the building for him or her. The architect will produce a set of drawings that show the outline and constructional details of the building. He will also normally produce site plans that the builder will use to locate the building on its site. Often the architect will also produce the location diagrams for electrical e lectrical as well as other services. The clever electrician will obtain a set of these to work with in pricing the job, working out the mains cable routes etc. prior to applying for supply etc. Site plans can be simple sketches or detailed cad drawings. The net result is the same. They should identify the location of the site, Show outlines of all buildings and other major features and show measurement detail. A simple example follows.
This example site plan drawing, is taken from AutoCad LT, the plan shows a site with a building, paths and car parking. This particular drawing is using imperial measurements but metric measurements would be more appropriate in New Zealand. With any site plan it is easy to add the mains cable route, the location of the meter box, the location of the pillar box from which the supply is obtained and the sizes of the cables etc.
Location diagrams When we consider our site plan, (above) we can see enough detail to install our mains cable, earthing, our meter box and main switch board. When we come to wire the house or flat, we need more detail. This is where the location diagram comes in. Once again the architect will usually draw an electrical location diagram as a part of the overall set of plans for the construction, and all we need do is follow these. If they don’t exist you can get a copy of the builder’s plans and add your electrical location information to a floor plan. The following drawing is taken from “Electrotechnology – Principles and Practice”.
Single line - power distribution diagrams Power supply companies and those working with commercial or industrial installations generally use these diagrams. This particular drawing is of the 11kV distribution at an industrial site. It shows 2 incoming 11kV feeders from a local sub station as well as a co-generation plant feeding a split-able 11kv main switchboard complete with metering.
This Section of the diagram shows the Sub-Station main 11kV switchboard, the 33kV feed to this board and the circuit breakers on this switchboard. CB4 shows additional protection relays. The line down from CB4 also shows the boundary between the power company and the site. Beyond this the VT’s & CT’s for the site protection relays are shown along with the protection relay circuits.
The other feeder at the left of this section also has the protection circuit displayed in the overall drawing.
This section of the diagram shows a part of the site ring-main. RMU5 (ring main unit 5) shows 2 isolators coming in and leaving the RMU. On the other side of the Bus you can see three 80A fuse switches feeding transformers. The 400V side of each transformer feeds another Bus for 400Volt distribution further down.
Note the Bus coupler between the sections of the main distribution for the two boilers, along with the two transformers being fed from different RMU’s you have several options for a more secure source of supply.
These drawings are obviously from a real site situation and are incomplete. However there is enough information in them to show you what the “Single line” diagram represents. Each line actually covers three phases Neutral & Earth’s as appropriate.
Common Symbols
AS/NZS 1102 general symbols symbols Commonly accepted symbol for direct current (d.c.) - not the only symbol.
Commonly accepted symbol for alternating current (a.c.). Suitable for use with either alternating or direct current. Positive polarity. Negative polarity. N
Neutral Material, unspecified Material, solid Material, liquid Material, gas Material, electret - (permanently polarised dielectric - analogues to a permanent magnet), used in microphones. Material, semiconducting Material, insulating (dielectric)
Thermal operation Electromagnetic operation Radiation, non-ionising, electromagnetic (for example, radio waves or visible light) Radiation, ionising (X=X-ray, γ =Gamma =Gamma ray) Earth, general symbol Ground, general symbol Protective earth Protective ground Frame Chassis Fault Indication of assumed fault location Moving (for example sliding) contact
Conductors and Connecting Devices - 617.3 (AS 1102.103)
Conductor, or group of conductors, or line, or cable, or circuit Three conductors 3
500V 2 Χ 70mm2 Al
3N
50 Hz 40 400V
3x6+1x4
Three conductors EXAMPLE: Direct current circuit, 500V, two 70mm2 Aluminium conductors. EXAMPLE: 3-Phase circuit, 50Hz, 400V, three conductors of 6.0mm2, with a neutral of 4.0mm2.
Flexible conductor Screened conductor n conductors within one screen
n
Two twisted conductors Three conductors in a cable Conductor or cable not connected Conductor or cable not connected and specially insulated Connection of conductors Terminal (NOTE: The circle may be filled in) Terminal strip (numbered) 1
2
3
4
5
6
Socket (female) - pole of a socket Plug (male) - pole of a plug Plug and socket (male and female) 4
Multipole plug and socket with 4 poles Junction of conductors Double junction of conductors
Crossing conductors not connected (NOTE: No join)
Connecting link, closed Connecting link open
Passive Components - 617.4 (AS 1102.104)
Resistor, general symbol Variable resistor (adjustable resistor) Varistor (voltage dependant resistor) U
Resistor with sliding contact Potentiometer with sliding contact Potentiometer, preset Resistor with fixed tapping (1 shown) Heating element Capacitor, general symbol
Polarised capacitor, for example, electrolytic
Variable capacitor, adjustable capacitor
Capacitor with preset adjustment
Inductor, Coil, Choke, Winding Inductor with magnetic core Inductor with fixed tappings (two shown) Piezoelectric crystal with two electrodes
Semiconductors and Electron Tubes - 617. 5 (AS 1102.105)
Semiconductor diode, general symbol Light emitting diode, general symbol Voltage regulator diode (Zener diode) Bidirectional diode - Diac - conducts in both directions and used for its pulse quality at switch-on
Triode Thyristor - (triode simply means three terminal) – this symbol does not specify the gate Thyristor (triode) - P-Gate (SCR) Bidirectional triode Thyristor - Triac (can control the ac power available to the load). PNP Transistor
NPN Transistor
Light dependant resistor Photodiode Phototransistor, PNP type shown
Optical coupling device (optocoupler) Hall generator with four ohmic connections X
NOTE: THIS PART OF THIS MANUAL DOES NOT INCLUDE THE ENTIRE AS 1102.105, JUST SELECTIONS FROM THAT STANDARD - WE HAVE NOT INCLUDED ANY ANY ELECTRON ELECTRON TUBES HERE.
Production and Conversion of Electrical Energy - 617. 6 (AS ( AS 1102.106)
Three-phase winding, Delta
Three-phase winding, Star
Brush (on slip-ring or commutator)
*
This is the general symbol for a machine. The * must be replaced with an appropriate letter: "G"-generator, "M"-motor, "MS"-synchronous motor etc. Motor
M
Linear motor M
Stepping motor M
d.c. two-wire series motor M
d.c. two-wire shunt motor M
a.c. series motor, single phase M 1
M 3
Induction motor, three-phase, squirrel cage
M
M 3
M 3
Induction motor, three-phase, squirrel cage Delta connected Induction motor, three-phase, with cage rotor, both leads of each phase brought out (squirrel cage motor) Induction motor, three-phase, with wound rotor
Transformer with two windings - two different methods of illustrating the same thing. The symbol on the left is more commonly used in single line diagrams (ie., power transformers where there would be three-phases represented as one line). The dots on this transformer indicate the instantaneous voltage polarities Instantaneous currents entering the marked ends of the windings produce aiding fluxes. Autotransformer - two different methods of illustrating the same thing.
Current transformer - two different methods methods of illustrating the same thing. Adjustable transformer, general symbol Transformer with centre tapping on one winding
Three-phase transformer, connection stardelta
d.c. converter (switch-mode power supply)
Rectifier Rectifier in full-wave (bridge) connection Inverter Primary cell - NOTE: The longer line represents the positive terminal
Battery of primary cells The number of cells can be indicated as a number
Switchgear, Controlgear and Protective Devices 617. 7 (AS 1102.107)
Make contact (normally open) - this symbol is also used as the general symbol for a switch
The same as the symbol above only the small circle (which can be open or filled) represents a hinge-point Break contact (normally closed)
Change-over break before make contact
Two-way contact with centre-off position
Make contact delayed when closing (operating device actuated), two shown. Break contact delayed when re-closing (operating device released), the two shown correspond with those vertically above. Make contact with spring return
Break contact with spring return
Manually operated switch, general symbol
Push-button switch (non-locking)
Pull-switch (non-locking)
Position switch (limit switch), make contact
Position switch (limit switch), break contact
t
Temperature sensitive switch, make contact (NOTE: t° may be replaced by operating temperature conditions.
Temperature sensitive switch, break contact t
Self-operating thermal switch, break contact
A contact of a thermal relay, break contact
Gas discharge tube with thermal element starter for fluorescent lamp (NOTE: the black dot represents gas) Push-button function may include letters (eg., ST-start, SP-stop, Rraise, L-lower, FWD-forward, REV-reverse, Ooff, UP-up, DN-down, JU-jog up, JD-jog down; example ST/SP denotes stop/start button. Emergency stop function Signal lamp function - the push button letter codes can be added to the symbol to indicate the function. Speed control function n
Contact on contactor (contact open in the un operated position)
Contact on contactor (contact closed in unoperated position) Contact on contactor with automatic release
Circuit breaker
Earth-leakage circuit breaker (ELCB) also known as a Residual Current Device (RCD), general symbol Miniature overcurrent circuit breaker with thermal and electromagnetic tripping. Disconnector - Isolator
Fuse, general symbol
Fuse-switch
Fuse-disconnector (fuse isolator)
Measuring Instruments, Lamps and Signaling Devices 617. 8 (AS 1102.108)
Voltmeter
V Ammeter
A Ohmmeter
Ω Galvanometer
Wattmeter (Dynamometer, Power meter)
W
Watt-hour meter Wh
Thermocouple, shown with polarity symbols
Clock with switch Signal lamp, flashing type
Discharge lamp - gas filled, general symbol Horn
Bell Siren
Buzzer
Symbols for Location Diagrams 617. 11 (AS 1102.8)
Wiring, line or cable Link between a switch and its associated remote socket-outlet or equipment Junction box involving a cable joint
Mains connection box at point of attachment of the incoming supply service mains, mains entry box. Switchboard, distribution board, frame, panel, or cubicle Switch, general symbol One-way switches, single-pole, two-pole and three-pole Single-pole pull switch Multi-position switch for different degrees of lighting Two-way switch, single pole
Intermediate switch Dimmer switch Period-limiting switch
t
Push-button switch
n
n
Push-button switch with integral indicator lamp Socket-outlet - NOTE: In New Zealand practice, this symbol represents a singlephase general purpose outlet, switched and earthed. Multiple socket-outlet, e.g. for n plugs Switched-outlet - This symbol may some times be more appropriate Multi-phase socket-outlet Socket-outlet with isolating transformer, e.g. a shaver outlet
Electric water heater
Electric fan - NOTE: This symbol may be further qualified by the use of abbreviations (e.g. EF - Exhaust Fan) Lighting outlet position, e.g. batten holder Lighting outlet on wall Luminaire, or signal lamp Luminaire fixed to wall Luminaire on mounting bracket for pole or wall Luminaire with built-in switch Luminaire with reflector
Industrial type luminaire, e.g. highbay Emergency lighting luminaire, e.g. standby or escape lighting Fluorescent luminaire - NOTE: It is normal practice to draw the length of fluorescent luminaires to scale.
3
Fluorescent luminaire with three lamps (two examples)
Fluorescent luminaire, outdoor type - NOTE: The number of lamps and rating may be added.
Fluorescent luminare, outdoor type, with mounting bracket Electrical appliance, general symbol. Appliance type may be described by abbreviation (e.g. HD - Hand Drier) Unequipped wall-telephone outlet Equipped wall-telephone outlet (with standard service installed unless otherwise qualified) Control units for Intruder alarm equipment (two shown).
