Non-Latching Relays

Relays are electrical switches that are operated by electrical impulses with the primary function to open and close a circuit, they can also be referred to as industrial switches. There are 2 main types available, latching and non–latching relays.

How do non-latching relays work?

Non-latching relays are in a normally closed (NC) position and will stay in this state without power. When power passes through the circuit, the relay switched to a normally open (NO) position by using an internal coil to generate a magnetic force, holding this NO position. Once the current is turned off, it returns to the NC position. This makes non-latching relays well suited to push-button applications like keyboards and micro-controller input buttons.

What are non-latching relays used for?

Non-latching relays are highly durable and versatile components, making their performance long lasting and suitable for use in a wide range of applications, such as:

• Automotive engines


• Household appliances


• Industrial machinery


• Medical equipment


• Telecommunications equipment

What is the difference between latching and non-latching relays?

Both types of relays in similar in design and function, however, a significant difference between them is that a latching relay will remain in the last position it when it was last powered, whereas a non-latching goes back to its normal position. This makes each more type of relay suitable for different applications.

Considerations when selecting a relay

When choosing a relay, it is important to consider a number of specifications to ensure it is fit for purpose, some factors include:

• Coil voltage - the required voltage to actuate the switching mechanism. If a voltage is too high this could damage the components, if it is too low then it will not actuate.


• Contact configuration - This is the state the contacts are in without power. For example SPST, single pole single throw.


• Contact material - the relay contacts are available in many materials that have certain properties. Common materials are gold, silver, tin oxide and nickel


• Coil power - the amount of power (watts) the coil operates at. This must match the power in the circuit for correct function.


• Coil resistance - the amount of resistance (ohms) in the circuit that the coil creates.