The Phase Meter is fitted with a meter designed to indicate the phase angle (in degrees) between two ac voltages. Two LED indicators are built into the meter face: one is marked “lead” and the other is marked “lag.” By observing the state of the indicators, an unknown voltage can be compared to a known (reference) voltage and the meter will indicate how many degrees the unknown voltage is out of phase (lead or lag) with the reference voltage source. For this reason, this meter also functions as a synchroscope.