Electrical Installation Safety Trainer
AD 1 - MI 3399
89
In the left picture we set the maximum allowed leakage current to 4,4 mA. Since we
indicated that the alarm sounded when the limit was exceeded the test passed
(I
MEASURED
>
4,4 mA). The same goes for the minimum allowed earth resistance. The
IMD alarm sounded after the fault resistance reached 35 k
Ω. In both cases it can occur
that the button confirming IMD alarm was pressed too late and the device already
continued to the next value. In such case, it is recommended to perform both tests
manually.
Expected results with a simulated error
When simulating an error on the PE conductor the PE is disconnected from the circuit.
In this case, the IMD test shows no difference in measurement. To turn on the PE error
enable switch
S15
in the Application Trainer. To simulate the I
SFL
fault on IMD device
enable switch
S16
.
Figure 2-31: IMD simulated errors on an IT system
Since switch S15 disconnects the PE conductor the IMD test does not detect any error,
which is correct. It is recommended to perform the single fault leakage currents (I
SFL
)
test and the IMD test one after another to determine whether there is fault in the circuit
present.
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
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...
Page 74: ...Electrical Installation Safety Trainer AD 1 MI 3399 74...
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Page 204: ...PAT Appliances Machines Safety Trainer AD 3 MI 3399 204...
Page 249: ...PV Photovoltaic Systems Trainer AD 4 MI 3399 249...
Page 250: ...PV Photovoltaic Systems Trainer AD 4 MI 3399 250 AD 4 MI 3399 PV Photovoltaic Systems Trainer...
