The TDP Percentage is a timer relay output that has an on/off ratio from 0% (Off) - 100% (On).
The internal relay of the device energizes once voltage is applied thus ON time starts. Once it is complete, the relay de-energizes and starts the OFF time. The cycle of on/off is completed once the off time is finished. The cycle carry on until the voltage is removed.
The relay comes with a knob or lock shaft adjustments and a plug-in style enclosure. Its models ranges from 60 sec to 60 minutes.