The M3 LCR meter has a special function to determine the turns ratio between the primary and secondary windings of a transformer, calculate the secondary voltage for a power transformer, and measure the mutual inductance between the primary and secondary winding.
The use of this option requires the 4-wire cable provided with the LCR meter. To enter this mode, press the n/Vs/M key. Connect the HD and LD clips to the winding having the greater number of turns and the HS and LS clips to the smaller winding. For a low voltage transformer (i.e., 115VAC primary and 24VAC secondary), the primary will be the larger winding and for a high voltage transformer (i.e., 115VAC primary and 800VAC secondary), the secondary winding will be the larger. See figure 1-3, page 20 for typical connection.
Incorrectly connecting the test clips to the transformer will result in an OVERFLOW condition being displayed on the LCD.