Different Types of Electrical Protection Symbols and Diagrams


Different Types of Electrical Protection Symbols and Diagrams


Hey, in this article we are going to see different types of electrical protection symbols. These symbols will be very helpful for you when you are going to read or understand different types of electrical power transmission and distribution wiring diagrams. The electrical power systems consist so many many protective devices such as circuit breakers, protective relays, earthlings, groundings, etc. so, when you are going to understand the wiring and connection diagram of the power system, you must know these protection symbols.

Thermal Protection


Thermal means heat. In an electrical circuit, heat is produced due to the flow of current through a resistor or resistive material, component, etc. When the flowing current exceeds the limit or rating of the device, component, or circuit, heat is produced. There are so many protective devices that are used for the protection against overcurrent flow and they work in the principle of sensing heating or thermal mechanism. Generally, they sense the heat produced by the flowing current and can measure the flow of current. Here, you can see the symbol of Thermal Protection.

Thermal Protection Symbol


The thermal protection system may consist of a thermal overload relay, thermal contacts, thermal switch, etc.


Overcurrent Relay Protection


The overcurrent relay is generally a current sensing relay. It is designed to actuate its contact when the flow of current through its magnetic coil exceeded a limit. In, normal conditions, its coil always carries a flow of current but does not actuate, when the flow of current through it exceeds the limit, it will actuate. Generally, a Relay has an NC(Normally Closed) Contact or a NO(Normally Open) Contact. When the relay is actuated, its NO contacts become NC, and NC contacts become NO. Here, you can see the symbol of overcurrent relay protection.

Overcurrent Relay Protection Symbol




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Short Circuit Protection


A short circuit protection system consists magnetic contact mechanism or electronic sensing circuitry. Generally, all the circuits breaker such as MCB, MCCB are had magnetic contact mechanisms for the protection of short circuit faults. They have a magnetic coil also known as No Volt Coil. When a short circuit fault occurs in a circuit a very high current will flow which energized the magnetic coil or no-volt coil of the circuit breaker. Once the magnetic coil of the circuit breaker is energized they break the contacts immediately and disconnect the power supply. Here, you can see the symbol of short circuit Protection.

Short Circuit Protection Symbol



Surge Protection


When the voltage in a circuit raises suddenly to a very high value for a very short time, then it is called surge voltage. The surge voltage is sometimes called transient voltage. generally, the surge voltage occurs due to switching, lightning, etc. Surge voltage protection systems use surge protectors, arcing horns, etc. Generally, most of the surge protection systems have two conductors placed very near to each other but not connected to each other. These conductors are placed in a vacuum or filled with a gas. So, when a surge voltage occurs in the circuit the voltage across those two conductors are very high and create an ARC. This ARC will create a closed path to flow the current to the ground. Here, you can see the symbol of Surge Protection.

Surge Protection Symbol



Transient Voltage Suppression Protection


Here, you can see the symbol of Transient Voltage Suppression or TVS Diode that is used in electrical devices or equipment for the protection against Transient voltage.

Transient Voltage Suppression Protection Symbol




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Different Types of Electrical Protection Symbols and Diagrams Different Types of Electrical Protection Symbols and Diagrams Reviewed by Author on 11/04/2021 Rating: 5
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