NEPTUNE
EN - 41
Switch conditions
Spot where to
perform
measurement
Measureme
nt
System evaluation
1.
Open switches A, D
and E
On switch A
If R
R
LIMITE
OK
(end of test)
If R
R
LIMITE
Proceed to
2
2.
Open switch B
On switch A
If R
R
LIMITE
Proceed to
3
If R
R
LIMITE
Insulation between switches
A and B is too low. Restore
insulation and measure again.
3.
On switch B
If R
R
LIMITE
OK
(end of test)
If R
R
LIMITE
Insulation is too low
downstream of switch B.
Proceed to
4
4.
Open switch C
On switch B
If R
R
LIMITE
Proceed to
5
If R
R
LIMITE
Insulation between switches
B and C is too low. Restore
insulation and measure again.
5.
On switch C
If R
R
LIMITE
OK
(end of test)
If R
R
LIMITE
Downstream of switch B,
insulation is too low. Restore
insulation and measure again.
Table 3: Procedure for measuring insulation in he system reported in Fig. 45
In the presence of a very extended circuit, wires running side by side constitute a capacity
that the instrument must load in order to obtain a correct measurement; in this case it is
advisable to hold the start button of the measurement (in case you run the test in manual
mode) until the result is stable.
When performing measurements between active conductors, it is absolutely necessary to
disconnect all users (alarm lights, intercom transformers, etc.), otherwise the instrument
will measure their resistance instead of the system
’
s insulation. Moreover, an insulation
resistance test between active conductors may damage them.
The
“
> full scale
”
message indicates that the insulation resistance measured by the
instrument is higher than the maximum measurable resistance value. This result is
obviously much higher than the minimum limits in the standard table above, so the
insulation in that spot is to be considered as compliant with the standards.
