Electrical Installation Safety Trainer
AD 1 - MI 3399
96
Expected results with a simulated error
In an installation with an insulation error between conductors, the measured insulation
resistance usually decreases to approx. 0,45 M
Ω. To measure such a situation enable
the switch
S32
as indicated in Figure 2-37.
Figure 2-37: R
ISO
simulated error between phase and neutral conductors
The fastest way to find the fault is to measure R
ISO
at the switchboard in the same way
as before (chapter Expected results above). After we see an error in the system, we
enable continuous measurement of the measuring device. We now measure only
between conductors that show a fault in the circuit simply by disabling all subsequent
fuses and RCDs in our measuring subsystem. The fuse/RCD that remains with the
fault is the circuit that has the fault.
As seen from the picture above the added insulation fault caused the measured
insulation resistance is much lower than required. This tells us the wiring should be
checked.
E
xer
ci
ses
S
w
itch
Function
Site of error
ON
OFF
S27 R
ISO
IT F3/1
L1/L2 outlet
approx. 0.45 MΩ
> 200 M
Ω
S28 ISFL/IMD
IT F3/1
L1/PE outlet
approx. 3 mA
< 1 mA
S29 I
Δ
TN/TT F2/2
L1/PE outlet
approx. 5.1 mA (@230 V)
approx. 2.5 mA (@115 V)
< 3.5 mA
S30 R
ISO
TN/TT F1/2
L1/PE outlet (3-ph.)
capacitive 1.45 MΩ
> 200 M
Ω
S31 R
ISO
/ VARISTOR
TN/TT SPD
GAS / PE
shorted
U
SPD
approx. 150 V
S32 R
ISO
TN/TT F1/2
L2/N outlet (3-ph.)
approx. 0.45 MΩ
> 200 M
Ω
S33 R
ISO
TN/TT F1/2
L1/L2 outlet (3-ph.)
approx. 0.45 MΩ
> 200 M
Ω
In
s
u
la
tio
n
r
e
s
is
ta
n
c
e
Summary of Contents for MI 3399
Page 27: ...Electrical Installation Safety Trainer AD 1 MI 3399 27...
Page 46: ...Electrical Installation Safety Trainer AD 1 MI 3399 46 3 Exit settings...
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