The PTA Series is a microprocessor-based Percentage Timer that delivers reliable and accurate timing for critical applications where the ON time (t1), as a percentage of the total cycle time, must be adjustable. The fi xed overall length (t2) of the repeating ON/OFF cycle is selected as the time range with multiple ranges off ered in seconds, minutes, and hours. Typical applications include controls for irrigation, chemical feeding, electric heating & cooling, motors and lubrication systems.