How to read electric schematic diagrams

How to read electric schematic diagrams

The schematic electric circuit of the device is intended for full and evident reflection of communications between device elements. It can also be used when studying automated control systems. Without ability to understand electric circuits it is impossible to understand the principle of operation of any given device and to make the required changes to it.


1. Study the scheme and the list of the elements making structure of a technical system which is attached to it. Find each of components on the schematical image, note for yourself their relative positioning. If text explanations are attached to the scheme, also study them.

2. Begin studying the scheme and definition of the power supply system. It includes a power source, windings of magnetic actuators, the relay and electromagnets if those are provided by the scheme. Determine its look, a sort of the used current, phasing or polarity by each power supply (depending on whether the alternating or direct current is used in the device). Check whether there correspond paramerta of electronic devices to the ratings specified in the technical specification on the device.

3. Define where elements of switching and protective devices are located. It is about the relay of the maximum current, safety locks and automatic regulators. Using inscriptions on the electric circuit, find zones of protection of each of such elements.

4. In the presence in the device of electroreceivers, for example, of the electric motor, actuator windings and so on, carry out their analysis. Track all chains of the specified elements from one pole of the power supply to another. Note arrangement in these chains of diodes and resistors.

5. Each of elements of a chain has the purpose which you should establish. You make at the same time an assumption that any given resistor, the condenser or the diode in the scheme is absent. To what consequences will it lead? Such conditional consecutive exception of elements of the scheme will help you to establish function of each separate device.

6. Studying the schematic diagram, you always remember what purpose facing you. Most often reading the scheme is required for understanding purpose of all device, entering into its work of improvements. Quite often schematic diagram allows to reveal mistakes in installation and to establish possible causes of defect of the electric device owing to failure of its elements.

Author: «MirrorInfo» Dream Team