Measuring 1000V on insulation tester and lock function

QUsing the IR4057 Insulation Tester, I turned the switch to 1000V and pressed measure but nothing happened.


To prevent accidental application of high voltages such as 1000V or 500V, there is a safety release lock on the instrument.  When using the 500V/1000V range, please press the RELEASE button to deactivate the safety lock. 

This applies to the following insulation testers:

Please refer the instructions below for more information.