METREL MI 3399, Instruction Manual With Exercises

Page: 87 / 272

Electrical Installation Safety Trainer AD 1 - MI 3399
87
Figure 2-30: ISFL simulated errors on an IT system
In both cases the measured fault currents increased above the allowed value which
means that the contact voltage is above the safety limit during the single fault condition.
As expected in such case the tests failed.
2.5.2.2 Exercise No. 2.5-2: Verification of insulation monitor devices
(IMD)
Measuring procedure
1 To measure the single fault leakage currents select first the IMD function in the
Other section.
E
xer
ci
ses
S
w
itch
Function Site of error ON OFF
S15 R LOW / IMD
IT F3/1
PE outlet
> 20
Ω
< 1
Ω
S16 ISFL / IMD
IT F3/2
ISFL approx. 6 mA (@ 230 V)
approx. 3 mA (@ 115 V)
< 1.3 mA
S17 R LOW IT PE ref.
approx. 3.3 Ω < 1 Ω
S18 R LOW
TN/TT F1/4
PE light
> 20
Ω < 1 Ω
S19 R LOW / Z LOOP
TN/TT F1/2
PE outlet (3-ph.)
approx. 3.4 Ω < 1 Ω
S20 R LOW / Z LOOP
TN/TT F2/2
PE outlet
> 2.3
Ω < 2 Ω
S21 R LOW MPE / PE Gas
approx. 2.2 Ω < 1 Ω
S22 R LOW MPE / PE Heat inst.
approx. 3.3 Ω < 1 Ω
P
E
C
o
n
n
e
c
tio
n
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
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e