Electrical Symbols — Switches and Relays

The vector stencils library "Transformers and windings" contains 29 element symbols of transformers, windings, couplers, metering devices, transductors, magnetic cores, chokes, and a variometer.
Use it to design the electromechanical device schematics and electronic circuit diagrams.
"A transformer is an electrical device that transfers energy between two circuits through electromagnetic induction. Transformers may be used in step-up or step-down voltage conversion, which 'transforms' an AC voltage from one voltage level on the input of the device to another level at the output terminals. This special function of transformers can provide control of specified requirements of current level as an alternating current source, or it may be used for impedance matching between mismatched electrical circuits to effect maximum power transfer between the circuits.
A transformer most commonly consists of two windings of wire that are wound around a common core to induce tight electromagnetic coupling between the windings. The core material is often a laminated iron core. The coil that receives the electrical input energy is referred to as the primary winding, while the output coil is called the secondary winding.
An alternating electric current flowing through the primary winding (coil) of a transformer generates an electromagnetic field in its surroundings and a varying magnetic flux in the core of the transformer. By electromagnetic induction this magnetic flux generates a varying electromotive force in the secondary winding, resulting in a voltage across the output terminals. If a load impedance is connected across the secondary winding, a current flows through the secondary winding drawing power from the primary winding and its power source." [Transformer. Wikipedia]
"An electromagnetic coil (or simply a "coil") is formed when a conductor is wound around a core or form to create an inductor or electromagnet. When electricity is passed through a coil, it generates a magnetic field. One loop of wire is usually referred to as a turn or a winding, and a coil consists of one or more turns. For use in an electronic circuit, electrical connection terminals called taps are often connected to a coil. Coils are often coated with varnish or wrapped with insulating tape to provide additional insulation and secure them in place. A completed coil assembly with one or more set of coils and taps is often called the windings.
Windings are used in transformers, electric motors, inductors, solenoids, loudspeakers, and many other applications." [Electromagnetic coil. Wikipedia]
The shapes example "Design elements - Transformers and windings" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Switches and relays" contains 58 symbols of electrical contacts, switches, relays, circuit breakers, selectors, connectors, disconnect devices, switching circuits, current regulators, and thermostats for electrical devices.
"In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.
The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts, which are connected to external circuits. Each set of contacts can be in one of two states: either "closed" meaning the contacts are touching and electricity can flow between them, or "open", meaning the contacts are separated and the switch is nonconducting. The mechanism actuating the transition between these two states (open or closed) can be either a "toggle" (flip switch for continuous "on" or "off") or "momentary" (push-for "on" or push-for "off") type.
A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. Automatically operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another workpiece. Switches may be operated by process variables such as pressure, temperature, flow, current, voltage, and force, acting as sensors in a process and used to automatically control a system. ... A switch that is operated by another electrical circuit is called a relay. Large switches may be remotely operated by a motor drive mechanism. Some switches are used to isolate electric power from a system, providing a visible point of isolation that can be padlocked if necessary to prevent accidental operation of a machine during maintenance, or to prevent electric shock." [Switch. Wikipedia]
"A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits as amplifiers: they repeated the signal coming in from one circuit and re-transmitted it on another circuit. Relays were used extensively in telephone exchanges and early computers to perform logical operations.
A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called "protective relays"." [Relay. Wikipedia]
The shapes example "Design elements - Switches and relays" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Lamps, acoustics, readouts" contains 35 element symbols of lamps, acoustic components, electrical measuring instruments for drawing electrical schematics and electronic circuit diagrams.
"Electrical measurements are the methods, devices and calculations used to measure electrical quantities. Measurement of electrical quantities may be done to measure electrical parameters of a system. Using transducers, physical properties such as temperature, pressure, flow, force, and many others can be converted into electrical signals, which can then be conveniently measured and recorded." [Electrical measurements. Wikipedia]
"A lamp is a replaceable component such as an incandescent light bulb, which is designed to produce light from electricity." [Lamp (electrical component). Wikipedia]
"An electric bell is a mechanical bell that... functions by means of an electromagnet. When an electric current is applied, it produces a repetitive buzzing or clanging sound." [Electric bell. Wikipedia]
"A buzzer or beeper is an audio signalling device, which may be mechanical, electromechanical, or piezoelectric." [Buzzer. Wikipedia]
"Electronic sirens incorporate circuits such as oscillators, modulators, and amplifiers to synthesize a selected siren tone (wail, yelp, pierce/ priority/ phaser, hi-lo, scan, airhorn, manual, and a few more) which is played through external speakers." [Siren (noisemaker). Wikipedia]
"A microphone (colloquially called a mic or mike...) is an acoustic-to-electric transducer or sensor that converts sound in air into an electrical signal. ...
Most microphones today use electromagnetic induction (dynamic microphone), capacitance change (condenser microphone) or piezoelectric generation to produce an electrical signal from air pressure variations." [Microphone. Wikipedia]
The symbols example "Design elements - Lamps, acoustics, readouts" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Transmission paths" contains 43 symbols of power transmission paths, electronic circuits, bus connectors and elbows, terminals, junctions, and concentrators.
Use it to annotate electrical diagrams, electronic schematics and circuit diagrams.
"A physical medium in data communications is the transmission path over which a signal propagates.
Many transmission media are used as communications channel.
For telecommunications purposes in the United States, Federal Standard 1037C, transmission media are classified as one of the following:
(1) Guided (or bounded) - waves are guided along a solid medium such as a transmission line.
(2) Wireless (or unguided) - transmission and reception are achieved by means of an antenna.
One of the most common physical medias used in networking is copper wire. Copper wire to carry signals to long distances using relatively low amounts of power. The unshielded twisted pair (UTP) is eight strands of copper wire, organized into four pairs.
Another example of a physical medium is optical fiber, which has emerged as the most commonly used transmission medium for long-distance communications. Optical fiber is a thin strand of glass that guides light along its length.
Multimode and single mode are two types of commonly used optical fiber. Multimode fiber uses LEDs as the light source and can carry signals over shorter distances, about 2 kilometers. Single mode can carry signals over distances of tens of miles.
Wireless media may carry surface waves or skywaves, either longitudinally or transversely, and are so classified.
In both communications, communication is in the form of electromagnetic waves. With guided transmission media, the waves are guided along a physical path; examples of guided media include phone lines, twisted pair cables, coaxial cables, and optical fibers. Unguided transmission media are methods that allow the transmission of data without the use of physical means to define the path it takes. Examples of this include microwave, radio or infrared. Unguided media provide a means for transmitting electromagnetic waves but do not guide them; examples are propagation through air, vacuum and seawater.
The term direct link is used to refer to the transmission path between two devices in which signals propagate directly from transmitters to receivers with no intermediate devices, other than amplifiers or repeaters used to increase signal strength. This term can apply to both guided and unguided media.
A transmission may be simplex, half-duplex, or full-duplex.
In simplex transmission, signals are transmitted in only one direction; one station is a transmitter and the other is the receiver. In the half-duplex operation, both stations may transmit, but only one at a time. In full duplex operation, both stations may transmit simultaneously. In the latter case, the medium is carrying signals in both directions at same time." [Transmission medium. Wikipedia]
The shapes example "Design elements - Transmission paths" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "VHF UHF SHF" contains 52 symbols for VHF, UHF, and SHF circuit design, including capacitance measurers, nonreciprocal devices, modulators, phase shifters, field polarization devices, and filters.
"Very high frequency (VHF) is the ITU-designated range of radio frequency electromagnetic waves from 30 MHz to 300 MHz, with corresponding wavelengths of one to ten meters. Frequencies immediately below VHF are denoted high frequency (HF), and the next higher frequencies are known as ultra high frequency (UHF).
Common uses for VHF are FM radio broadcasting, television broadcasting, land mobile stations (emergency, business, private use and military), long range data communication up to several tens of kilometres with radio modems, amateur radio, and marine communications. Air traffic control communications and air navigation systems (e.g. VOR, DME & ILS) work at distances of 100 kilometres or more to aircraft at cruising altitude.
VHF was previously used for analog television stations in the US." [Very high frequency. Wikipedia]
"Ultra-high frequency (UHF) designates the ITU radio frequency range of electromagnetic waves between 300 MHz and 3 GHz (3,000 MHz), also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres; that is 1 decimetre to 1 metre. Radio waves with frequencies above the UHF band fall into the SHF (super-high frequency) or microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is high enough for indoor reception. They are used for television broadcasting (digital and analogue), cordless phones, walkie-talkies, satellite communication, and numerous other applications.
The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE radar band overlap the ITU UHF band: the L band between 1 and 2 GHz and the S band between 2 and 4 GHz." [Ultra high frequency. Wikipedia]
"Super high frequency (or SHF) is the ITU designation for radio frequencies (RF) in the range of 3 GHz and 30 GHz. This band of frequencies is also known as the centimetre band or centimetre wave as the wavelengths range from ten to one centimetres. These frequencies fall within the microwave band, so radio waves with these frequencies are called microwaves. The small wavelength of microwaves allows them to be directed in narrow beams by aperture antennas such as parabolic dishes, so they are used for point-to-point communication and data links, and for radar. This frequency range is used for most radar transmitters, microwave ovens, wireless LANs, cell phones, satellite communication, microwave radio relay links, and numerous short range terrestrial data links. The commencing wireless USB technology will be using approximately 1/ 3 of this spectrum.
Frequencies in the SHF range are often referred to by their IEEE radar band designations: S, C, X, Ku, K, or Ka band, or by similar NATO or EU designations." [Super high frequency. Wikipedia]
The shapes example "Design elements - VHF UHF SHF" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.

The vector stencils library "Inductors" contains 41 symbols of inductor elements for drawing electronic circuit diagrams.
"An inductor, also called a coil or reactor, is a passive two-terminal electrical component which resists changes in electric current passing through it. It consists of a conductor such as a wire, usually wound into a coil. When a current flows through it, energy is stored temporarily in a magnetic field in the coil. When the current flowing through an inductor changes, the time-varying magnetic field induces a voltage in the conductor, according to Faraday’s law of electromagnetic induction, which opposes the change in current that created it.
An inductor is characterized by its inductance, the ratio of the voltage to the rate of change of current, which has units of henries (H). Inductors have values that typically range from 1 µH (10-6H) to 1 H. Many inductors have a magnetic core made of iron or ferrite inside the coil, which serves to increase the magnetic field and thus the inductance. Along with capacitors and resistors, inductors are one of the three passive linear circuit elements that make up electric circuits. Inductors are widely used in alternating current (AC) electronic equipment, particularly in radio equipment. They are used to block the flow of AC current while allowing DC to pass; inductors designed for this purpose are called chokes. They are also used in electronic filters to separate signals of different frequencies, and in combination with capacitors to make tuned circuits, used to tune radio and TV receivers." [Inductor. Wikipedia]
The symbols example "Design elements - Inductors" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Electrical Engineering solution from the Engineering area of ConceptDraw Solution Park.