A timer relay is a device used to turn a circuit on or off after a certain amount of time and, while many models seem similar, some factors will help you determine which relay is the best for your needs. If you have a basic circuit, then you may just need one timing range; if the circuit is more complex, then several delay settings may be required. The timer relay will have a minimum and maximum time limit, and these should be within satisfactory operating levels. Timers on this relay may come in either digital or analog styles. On-delay and off-delay features help run the relay when you are not around.
The main function of a timer relay is to open or close a circuit, but it must know when to perform this action. A basic relay will have just one timing range, meaning you can set the relay to open every five seconds, for example. Complex circuits may require several ranges; if there are two ranges, then you can set the circuit to open in alternating patterns of five seconds then three seconds. You should check the circuit to see how many ranges it will require for proper use.
Most timer relay devices have a minimum and maximum time limit, and you cannot set a lower or higher time than these limits. The common range is about 0.01 to 0.05 seconds for the minimum, and about 50 to 100 hours for the maximum. If your circuit needs a shorter or longer time, then check the relay’s specs to ensure it fits within your requirements.
Normally a timer relay has a clock face that allows you to set the relay times, and this face comes as either digital or analog. While this is normally a matter of preference, each relay face has its own purpose. A digital face makes it easier to set exact times, especially for very short or long time limits, while an analog face is typically less expensive and it may be easier to set for medium time limits.
A majority of timer relay devices have on-delay and off-delay functions to automate the relay’s use. For example, on-delay allows you to specify when the device will turn on; if you leave the relay alone, but it needs to start working in several hours, the delay will allow it to work without you coming back to the relay. While it is possible to use a relay without these functions, you may forget to turn the relay on or off, which can have bad effects for whatever the circuit controls. This means that getting a relay with one or both of these features is usually desirable.