Percentage Timers: Electronic Replaces Mechanical

A Percentage Timer is a time delay relay commonly used in applications such as irrigation, chemical feeding, electric heating & cooling, motors and lubrication systems.

The Percentage Timer provides an output that cycles ON & OFF continuously. The duty cycle of the ON time is adjustable in percent of the total cycle time. Total cycle times in seconds, minutes and hours are available. For example, a Percentage Timer with total cycle time of 1 minute, set to 10%, provides a 6 second ON TIME followed by a 54 second OFF TIME.  This cycle will keep repeating so long as voltage is applied to the Percentage Timer.

Early Percentage Timer designs were mechanical and used motors and gears to perform the timing function.  This mechanical design provided a timing cycle memory when power is removed or lost.  If, for example, power is lost 3 seconds into a timing cycle; the mechanical Percentage Timer will resume timing from 3 seconds when power is restored.  The mechanical nature of these early designs also means that they are susceptible to variations in voltage and frequency.  Such fluctuations will change the overall timing and repeat accuracy of the timer.  

Macromatic PTA series Percentage Timers are electronic and microprocessor based.  This design approach offers highly reliable, repeatable and accurate timing cycles. Changing voltage and frequency does not impact the time range or timing cycle. 

The PTA series is available with or without memory.  For applications that require memory, the standard PTA series retains timing cycle status when power is lost.  When power is restored the timer continues timing without resetting the timing cycle. 

For applications that do not require memory, Macromatic offers the product without memory as well (add a “B” suffix to the part number).  The non-memory version resets the timing cycle to zero when power is removed.  When power is reapplied, the timing cycle always starts at the beginning.

For more information about Macromatic PTA Series Percentage Timers, call 800-238-7474.