Electrical drawing symbols series#

Sometimes these lines can also indicate in combination with suitable additional symbols, a mechanical interlocking between two or more devices such as contactors or circuit breakers.Д©. Generally, it is associated with a push button or switch closing or opening a contact. A broken line in an electrical circuit represents mechanical action. Conversely, conductors having an electrical junction are represented with a dot at the intersection.ДЁ. Conductors intersecting each other with no electrical junction in between are represented with an intersection without any dot.

Electrical drawing symbols series#

Control circuit power lines are shown as L1 and L2 load (coils of relay) is connected between these two lines in series with switches, fuses, etc.Д§. In contrast, light-looking lines are used to represent low current-carrying conductors (control circuit lines).Д¦. In general, a heavy line is used to show high current-carrying conductors (mains supply lines, motor connection leads). To give the reader an exact idea of where it is used, a drawing mentions a cross-reference number for each contact showing the sheet number and its matrix number.ДҐ. Particular relay contacts may be used in different circuits at different locations. Contacts of the same contactor coil are shown with the same letter in the drawing.Д¤. In order to identify different coils and their contacts a letter such as K1, K2 or C1, C2 is placed next to the circle of the coil. Similarly, it is used to cross-reference a contact.ДЈ. This kind of matrix arrangement helps in quickly locating a particular device or contact in a sheet. An electrical drawing has a sheet number and each sheet is divided into columns listed vertically as A, B, C, D and horizontally as 1, 2, 3, 4. In addition, power devices such as circuit breakers and contactors are provided with NO and NC auxiliary contacts which are used for indicating the status of the device in signaling and interlocking circuits.Дў. It is either a timer NO/NC contact or a relay NO/NC contact in a circuit. The symbols shown for a device in a circuit represent its de-energized state when no power is applied. Things to look for in an electrical drawingДЎ. The push button mechanisms are lockable and need a key to release once the push button is pressed. The NC contact of such a push button is connected in series with the other control contracts such as overload relay. The schematics here depict only the fuse.ДЄn emergency switch or a push button has to be provided near a mechanism to positively isolate the electrical circuit feeding the mechanism in the case of any emergency/accident. Any power circuit has to be provided with an isolating mechanism which usually includes the fuses also in the form of a switch-fuse unit.These are however a MUST and will be insisted upon by the regulatory agencies. Various examples of electrical schematics are shown in this section to explain the drawing methodology in practical circuits and in the interest of simplifying the scheme the following have not been included. It is easy to trace the connections and continuity of wires, if the wires and terminals are numbered using thorough cross-referencing terminology. Wire and terminal numbers are quite useful during installation and termination of cables, and during fault finding and troubleshooting. Wire and terminal numbering (an important aspect in understanding electrical drawings).Sheet numbering and column format for each sheet.Their interconnections, legends, terminology, and abbreviations.Symbols used for representing electrical devices.To read and understand electrical drawings, it is necessary to know the following: Read ing and understanding electrical drawingsД®lectrical drawings can represent anything from a single-line power distribution, to a power or control circuit, and are prepared using various symbols for electrical devices and their interconnections with lines representing conductors or wires used for interconnections.