A Meggar digital insulation meter user manual warns:
"When using 500 V measurement to measure resistance less than 1.5 MΩ or 1000 V to measure resistance less than 5 MΩ, measurement time must not exceed 10 seconds."
The problem is that i need to make measurement beyond the 10 seconds - a measurement of 60 seconds and more.
I assume that when the measured resistance is less than 1.5 MΩ for 500 V and less than 5 MΩ for 1000 V, I might be able to exceed the 10 seconds, but how many seconds/minutes can I make the measurement according to the measured resistance? For instance, if i measured 10 MΩ with 500 V, can I make the measurement for 60 seconds, 3 minutes etc.? Is there a rule of thumb for this situation?