All Types of Relay Symbol and Diagram

In this article, we are going to see all types of Relay Symbol. If you are from an electrical or electronics background, then you must know the symbol of relay. The relay is an electrically operated switch. It has three sets of terminals - input terminals, output terminals, and control input terminals. The main function of a relay is to make or break an electrical or electronic circuit according to the input control signal.

Generally, two types of contacts are there in a relay - closed contact and open contact. In normal conditions, the closed contact remains closed and passes an electric current whereas the open contact remains open. But when a control signal is applied to the coil of the relay, its closed contact becomes open, and open contacts become closed.

All Types of Relay Symbol and Diagram, symbol of relay

There are so many different types of relay available according to their function, construction, terminals, etc. Here you can see the list of different types of relay as below.

Electromagnetic Relay
Thermal Overload Relay
SPST Relay
SPDT Relay
DPST Relay
DPDT Relay
Double Coil Latching Relay
Overcurrent Relay
Differential Relay
Pulse Relay
On/off time delay relay
Remanence Relay
No Volt Relay
AC Relay
DC Relay
Polarized Relay
Distance Relay or Impedance Relay

Electromagnetic Relay Symbol

The electromagnetic relay has a coil and contacts. When a power supply is applied to that coil it becomes an electromagnet and attracts the contacts to close or open. Here, you can see the symbol of the electromagnetic relay.

Thermal Overload Relay Symbol

Thermal Overload Relay does not have any magnetic coil. It has a bi-metallic strip. According to the magnitude of the flow of current, the bi-metallic strip get expands and causes the auxiliary contacts to get open or close. Here, you can see the symbol of the Thermal Overload Relay.

SPST Relay Symbol

SPST or Single Pole Single Throw Relay has only one contact either NO or NC. It has a total of four terminals including the coil terminals. Here, you can see the symbol of SPST Relay.

SPDT Relay Symbol

SPDT Relay or Single Pole Double Throw relay has a total of five terminals. Two for the magnetic coil and three for the contacts. In the contact mechanism, it has one common terminal, one NO terminal, and one NC terminal. Here, you can see the symbol of SPDT Relay.

DPST Relay Symbol

DPST relay or Double Pole Single Throw relay is the parallel combination of two SPST relays with a single magnetic coil. Including the coil terminals, it has a total of six terminals. Here, you can see the symbol of DPST Relay.

DPDT Relay Symbol

DPDT Relay or Double Pole Double Throw Relay is the parallel combination of two SPDT relays with single magnetic coils. Including the coil terminals, it has a total of eight terminals. Here, you can see the symbol of the DPDT Relay.

Latching Relay Symbol

Double coil latching relays are constructed with two magnetic coils. Most of the latching relays are DPDT types and they used the latching principle for their operation. Here, you can see the symbol of the latching relay.

Overcurrent Relay Symbol

As its name suggests the Overcurrent relay actuates when overcurrent flows through it. It allows the continuous flow of current through it and operates when the flow of current exceeds a limit. Here, you can see the symbol of overcurrent relay.

Differential Relay Symbol

Differential Relay actuates when there is any difference occurs in the same electrical quantity. Generally, it has two magnetic coils connected in such a way that when there is any difference occurs in the flow of current in those two coils, the differential relay will operate. Here, you can see the symbol of the differential relay.

Pulse Relay Symbol

Pulse Relay is mainly designed to operate with pulse signals. Pulse relay is used where frequent switch ON/OFF is required for a defined time. Here, you can see the symbol of Pulse Relay.

Time Delay Relay Symbol

On/Off Time Delay Relay has a time adjustment mechanism. It does not get off or on instantly. It always got on or off after the predefined delay time. Here, you can see the symbol of the Time Delay Relay.

Remanence Relay Symbol

Remanence Relay is designed with a Set and Reset mechanism. We can easily set or reset it. Remanence relay is available in both AC and DC categories. Here, you can see the symbol of Remanence Relay.

No Volt Relay Symbol

No Volt Relay or NVR is designed to operate with a very low voltage. Generally, the under-voltage relay is also called a no-volt relay. It actuates when a low voltage is applied across its coil terminal. Here, you can see the symbol of No Volt Relay.

AC Relay Symbol

AC and DC relays are different according to the type of power supply they need to operate. AC and DC relay coils have different internal resistances and different no. of turns.

Polarized Relay Symbol

Polarized Relays are constructed with a permanent magnet and a magnetic coil. It supplements the magnetic flux of the electromagnetic coil. Here, you can see the symbol of Polarized Relay.

Distance Relay Symbol

Distance Relay is also known as Impedance Relay. It is mainly used in electrical transmission lines. It actuates depending on the distance of the fault on the transmission line. Distance relay is used to find the location of the fault in the transmission line. It calculates the impedance to find out the distance of the fault. Here, you can see the symbol of Distance or Impedance Relay.

Solid State Relay Symbol

Solid State Relay is also known as SSR. It is built with semiconductor material. It does not have any electromagnetic coil or mechanical contacts. SSR operates more smoothly and faster than an electromagnetic or mechanical relay.

Stepping Relay Symbol

Here, you can see the symbol of Stepping Relay.

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