What is a Timer Relay?

A timer relay is an electrical control device used to delay the opening or closing of contacts in a circuit. It works like a normal relay but includes a built-in timer that controls when the relay coil energizes or de-energizes. Timer relays are widely used in automation, industrial control panels, motor control circuits, and safety systems.

Why Timer Relays Are Used?

Timer relays are used to:

• Start or stop machines/ Motor after a fixed time 
• Provide delay for safety interlocks
• Sequence operations (one motor after another)
• Avoid sudden load on electrical systems
• Control lighting, pumps, fans, and alarms
• Shifting STAR DELTA connection in Motor 

How a Timer Relay Works?

A timer relay has:

• Coil – energizes the relay
• Contacts (NO/NC) – switch the load
• Timing circuit – delays the switching action
• Time setting knob/display

When a voltage is applied:

1. The timer starts counting (ON delay or OFF delay)
2. After the set time, the contacts change state

Types of Timer Relays

Type	Description
ON-Delay Timer	Output turns ON after the set time when power is applied.
OFF-Delay Timer	Output turns OFF after the set time when power is removed.
Interval Timer	Output stays ON for a set time once triggered.
Cyclic / Repeat Timer	ON and OFF cycle continuously as per set times.
Star-Delta Timer	Used for motor starting sequence.

Applications of Timer Relay

• Motor Star-Delta starters
• Pump control
• Lighting control systems
• Automatic alarms and hooters
• Sequence control in automation panels
• Delay for heater, blower, conveyor