An electrical drawing, is a type of technical drawing that shows information about power, lighting, and communication for an engineering or architectural project. Any electrical working drawing consists of “lines, symbols, dimensions, and notations to accurately convey an engineering’s design to the workers, who install the electrical system on the job”.
An electrical diagram is a graphical representation of an electrical installation, using mainly electrical symbols and connections. This is in contrast to an electronic scheme which gives a representation of an electronic circuit.
In the electrical diagram, electrical components, electrical connections, operation and signaling are unambiguously recorded by encoding systems such as component numbering, terminal numbering, location, cable and wire numbering. The electrical components are shown symbolically on the electrical diagram. Complex schedules are displayed on multiple pages and use cross references. Data that is important for proper connection, operation and use are also listed on the schedule; the indication of the supply voltage, the placement mode, description of function of a signalization, range of measured values and signals, timers and thermos setting. Depending on the need, there are different types of electrical schemes.
A complete set of working drawings for the average electrical system in large projects usually consists of:
A plot plan showing the building’s location and outside electrical wiring
Floor plans showing the location of electrical systems on every floor
Power-riser diagrams showing panel boards
Control wiring diagrams
Schedules and other information in combination with construction drawings.
Electrical drafters prepare wiring and layout diagrams used by workers who erect, install, and repair electrical equipment and wiring in communication centers, power plants, electrical distribution systems, and buildings.
A schedule usually has multiple locations. The location is the physical location where the components of the schedule are located. A location also has multiple levels:
building level or designation of the hall in which the relevant cabinet is located. Each building must have a unique number in the company so that the location of the building is unambiguously stuck in a company’s layout drawing.
cabinet or machine level is the designation of a cabinet or machine in the building. The location box level is listed in the schedule on each page. Parts of the scheme in a different location are shown in an area with a dashed line, demarcated with their location indication. Each cabinet or machine must have a unique number in the building so that the location of the cabinet or machine is unambiguously stuck in a layout drawing of the building.
component level or designation of a component in the cabinet. Each component must have a unique number in the cabinet or machine so that the location of the component is unambiguously stuck in a layout drawing of the cabinet or machine.
clamp level or indication of the component’s clamp. Each electrical component connector must have a unique number so that the clamp location is unambiguously attached to the component.
In this way everything is clearly identified in the electrical scheme and can be precisely checked where each terminal is located.
An electrical installation as well as the schedule must be clear which requires tight construction. Each scheme is therefore composed of several circles, each of which has their typical function:
Power circuits divide the electrical energy from one plate to other boards or machines.
Power cuts are typical for the drive of an electric motor or machine. A power circuit is energized by a contactor. To protect the engine, the power circuit contains a thermal or motor protection device. If the drive is driven by a frequency converter, the actual control circuit will be directly coupled to the frequency converter.
Control circuits contain the switch logic to properly control the contactors of the power circuits. Control devices such as switches and pushbuttons, relays, electronic relays and possibly a Programmable Logic Controller (PLC) can be found in the control circuit. The contactor separates between the control circuit and the power circuit: The coil of the contactor has been included in the control circuit which determines the contactor pulling and some of the contactor’s auxiliary contacts. In the power circuit are the main contacts of the contactor.
Signalization provides information to the user by signal lights or buzers or other HMIs. This signal is binary (on or off) and can also be reported by signal contacts available to the user, such as a notification that the machine is in service or the machine is in malfunction.
Sensor rings connect sensors of the machine with a PLC or a transducer that makes an analog signal.
Analog circuits contain analog signals. In industry, standard signals are used, such as the 4-20mA or 0-10V signal. These signals can be a measured value of a sensor transformed into a standard signal by a measuring converter.
Because of the fact that a lot of electrical installations are being made, there are several types of schemes that everyone, but especially electronics, can use.
A diagram showing where the vein is connected to which clamp. Such a type of scheme is also called a clipboard or clip list.
A drawing showing the layout of (the front or inside of) an electrical device cabinet.
A schematic diagram (see section) of the configuration of an electrical installation, showing units (panels or controllers) as blocks. Such a scheme is also referred to as a configuration scheme.
A partial diagram shows part of an electrical system, characteristic of which the complete circuit of a component is displayed. Other connections to the component are not displayed directly, but often as a link to another schedule. Components from an electrical system can be returned in different (partial) schemes as opposed to the principle scheme (see there).
A single-wire diagram shows the principles of electrical installation in general. The single-line diagram shows the important components of the installation with their main features and the most important connections. Dashed lines often indicate the measurement signals and analog signals that control the protection relay or which control the switching equipment.
A scheme showing the lines with the number of veins and symbols in a single way. Such a scheme often shows (a part) of the configuration of an electrical installation. The function of a landscaping and a block diagram are often in line with each other.
A derivative of the landing scheme. This diagram shows the lines and symbols in a simple way, often from one or more light and power divider units. In addition, specific technical features of each group are often displayed, such as power output and nominal current. Also, for each distributor, the total expected ability is specified.
A drawing showing the exact location of electrical devices (such as switches, WCDs, data / telephony terminals) on an architectural map. Installation drawings can be subdivided into installation drawings for power groups (400 / 230Vac), light groups (230Vac), electrical engine compartments, grounding, communications and fire prevention. You can also combine these types of items into one (or more) drawing (s).
A list of all cables (part of) an electrical installation preferably on (alpha) numeric order.
Cable loop drawing
A drawing showing the course of cables. See also in the pipeline diagram.
The pipes and pipes used in the electrical installation are shown on the floor plan of the building where the installation is located. You can also place cable flags here. Then we speak of cable loop drawing.
Measurement and control scheme
A measurement and control scheme (or control circuit diagram) is a diagram showing how an instrument in the field is connected to the control unit. In the drawing, a measurement and control scheme corresponds to that of a circuit diagram. Because it is often instrumentation here, the device also lists various settings, often on the drawing itself, but also on separate specification sheets that belong to the schedule. In general, such a chart is also called walking diagram (English).
A drawing of the installation, indicating the electrical components (such as motors, switches and sensors) that control the installation.
This shows all the connections and components of an electrical system. All components in the system are shown schematically. Characteristic of a principle scheme is when the scheme is divided into different sections, each component will only occur once.
A circuit diagram is drawn to better understand an electrical circuit and to see how many wires are being applied. A distinction is made between mains voltage (400 / 230Vac) and steering current (lower voltages), so it is often common to use main flowchart and control flowchart.