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They are especially useful for monitoring the ageing of the insulation of
revolving machines or of very long cables.
On items of this type, the measurement is initially perturbed by spurious
currents (capacitive charging current, dielectric absorption current) that
gradually cancel out. To measure the leakage current representative of
the insulation accurately, it is therefore necessary to make measurements
of long duration.
The quality of the insulation is a function of the results found.
DAR
< 1.25
< 1.6
> 1.6
4.5.1
Adjustments of the PI
It is possible to modify the PI times to meet specific needs.
Reminder: PI = R
The first PI time is 1 min. It can be set to values from 30 sec to 30 min in
30 sec steps.
•
Press and hold the DISPLAY button and turn the rotary switch
to the SET V
appears in the display.
•
You can change the first PI time (PI_1) using the ▲ and ▼
buttons.
•
To save changes simply, turn the switch.
•
The second PI time (PI_2) is 10 min. It can be set to values from
PI_1 up to 59 min in 1 min steps.
•
Press and hold the DISPLAY button and turn the rotary switch to
the SET V
•
You can modify the second PI time using the ▲ and ▼ buttons.
•
To save changes simply, turn the switch.
Megohmmeter Model 6505
PI
< 1
< 2
< 4
> 4
R
10 min /
position. Hold the DISPLAY button until PI_1
VAR
position.
LOCK
Condition of the Insulation
Inadequate or even dangerous
Good
Excellent
1 min
21
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