Time relay symbol

Probe domestic switch needle KG-300K, needle head diameter is 3.0mm, normally open switch needle

Photocoupler

Interpretation: A time relay is an automatic switching device that uses electromagnetic or mechanical principles to achieve delayed control. It typically comes in two forms: power-on delay and power-off delay. Although there are only two main types, the graphical symbols of a time relay can be confusing when drawing or interpreting electrical schematics. Especially the time-delay contacts are often hard to identify in practical use. Let’s take a closer look and make it easier for you.

1. Time Relay Symbol - Introduction

A time relay is an automatic switching device that provides time-based control using electromagnetic or mechanical methods. It is commonly used in low-voltage or low-current circuits to control high-voltage or high-current devices. When an input signal is applied (or removed), the output circuit undergoes a precise time delay before changing state (e.g., making or breaking a contact). There are various types, such as air-damping, electric, and electronic relays.

2. Time Relay Symbol - Text Symbol

Text symbol:

3. Time Relay Symbol - Graphic Symbol

Coil general symbol:

Power-on delay symbol:

Power-off delay symbol:

4. Time Relay Symbol - Electrical Symbols

Normally open contact:

Normally closed contact:

Time-closed normally open contact:

Time-opening normally closed contact:

Delayed recovery of normally closed contacts:

Time-opened normally open contact:

The time relay is primarily used to implement time-based control in automatic systems. Its electrical symbol is also shown below for reference.

We’ve covered the key points about the time relay symbol. Did you get it all? If not, just review it a few times. Here are some additional resources to help you understand better. Don’t forget to practice and apply what you've learned!