Transmille 1000-Series - Manual (Page 64)

1000 SERIES OPERATION MANUAL
TRANSMILLE LTD. Version 1.30 Page 64
7) The 1000 Series will display the test voltage measured from the tester (UUT)
Note : If the polarity of the input from the insulation tester is reversed, the
1000 series will display INCORRECT INPUT. In this case, simply reverse
the input from the insulation tester to resolve this.