The Phase Head will quickly, accurately, and easily measure the phase sequence of a 400Hz source. At the same time it will also analyze the steady state AC voltage and compare it to MIL-STD-704. After the analysis is complete, the phone application will show a Pass or Fail as to whether you should connect the 400Hz to an aircraft or start troubleshooting and repair of the unit under test. All measured parameters are shown in the app with minimum and maximum limits.