Time relays, also called time delay relays provide a mechanism to switch a device on or off after a predetermined amount of time. Timed relays have many industrial applications to control time sensitive manufacturing processes and protect equipment under predefined power conditions. Timing relays operate in two modes, “off delay” and “on delay” and are triggered either buy the activation or deactivation of the electromagnet.

A time relay can be activated by starting a process, pushing a button or trigger or automatically when predefined heat, power level or other condition is identified by a sensor. Time delay relays require internal parts that are set to operate within a specific power level to ensure activation and deactivation is possible. Operating outside of the time relay's specifications is likely to cause the device to operate incorrectly or not at all. When looking for timing relays for your business consider the following:

1. Use normally open and closed time relays for simple power on and off applications.

2. Find watchdog time relay suppliers to activate warning lights, audio or complex sequences.

3. Utilize reliable mechanical timing relays in conditions where electronics are undesirable.

Action Steps
The best contacts and resources to help you get it done

Select time relay manufacturers with normal condition switches for single condition requirements

Normally open or normally closed timing relays perform the exact same operation using opposite activation conditions. Normally open relays activate when the coil is unpowered and closes on a delay when powered. Normally closed reverses the process by opening the connection when energization takes place.

I recommend: Precision Timer makes and sells timing relays for industrial switch applications. Use the quick find tool from National Controls Corporation (NCC) to match your application with the right timing delay relay.

Protect your electronic systems with programmable watchdog time relays

Watchdog timing relays also known as a programmable time delay relay are useful for watching computer or electronically controlled machinery. The machinery circuit continually sends a charge to the timing relay to show it is operational. If the system locks up or fails to keep the coil in the timing switch charged the delay will set off an alarm or start a predefined operation.

I recommend: Access Control Sales carries a full line of programmable watchdog timing relays to meet your business needs. Wholesale Electronics sells and easy to use 120 volt timing relay for convention power applications.

Rely on mechanical timing relays in adverse temperature, humidity and power source installations

Mechanical relays use pneumatic dashpots or fluid-filled pistons and cylinders to provide the delay motion of opening or closing the connection. Mechanical relays have an advantage when large power fluctuation or overload is a concern. Mechanical timing relays have no electronic components to burn out or lockup under repeated adverse power conditions.

I recommend: North Atlantic Industries (NAI) manufacturers a variety of timing relays with a choice of mechanical, thermal or electronic design. Time relay distributors, Grainger carries mercury liquid mechanical timing switches.

Tips & Tactics

Helpful advice for making the most of this Guide

• •  Time relays are designed to operate based on a specific electrical condition. Ensure the relay you select for your business matches the power specifications of your machinery.