Question:
What means "Safety Pretest for Insulation Resistance Measurements"?
Answer:
The 1664 FC model includes the feature "Safety Pretest" that detects any appliances connected to the circuit under test.
Safety Pretest gives you a warning before you start a test and prevents damage to appliances from the test voltage.
With the button F3 this feature can be switched on or off.
Safety Pretest OFF
With the setting Safety Pretest OFF, the installation tester immediately supplies the full test voltage as set with the key F4.
Safety Pretest ON
With the setting Safety Pretest ON setting, the installation tester increases the test voltage from 50V up to the test voltage as set with the key F4.
If case the test instrument detects a low resistance between L and N, the test instrument will stop the measurement immediately.
This prevents damage of connected equipment and appliances in the tested circuit.
Connection to circuit under test:
In order to carry out this safety pretest reliable, the test instrument must be connected with all 3 measuring connections (L, N, PE) to the circuit under test .