Model 25 True RMS 3-Phase Monitor has a display that shows the voltage with an accuracy of +/- 0.5%. The display is updated every second and re-initialized every 30 seconds. Model 25 has a rotary encoder with switch on the unit. By pressing the encoder switch for more than 5 seconds, the unit will enter the setup mode.This unit has a user selectable relay option for High-Low or DPDT. It can also be user-selected to energize on fault or de-energize on fault. The user can select automatic or manual restart on the Model 25. The Model 25 True RMS 3-Phase Monitor can be either calibrated using a True RMS Voltmeter or can be restored to factory defaults in the field.