METREL MI 3399, Инструкция с упражнениями

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Electrical Installation Safety Trainer AD 1 - MI 3399
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TABLE OF CONTENTS
1 Basic theory about LV Electrical Installations Safety and Measurements ......... 34
1.1 TN system ............................................................................................................34
1.1.1 TN-S system ................................................................................................................................... 34
1.1.2 TN-C system................................................................................................................................... 35
1.1.3 TN-C-S system ............................................................................................................................... 35
1.2 TT system ............................................................................................................36
1.3 IT system .............................................................................................................37
1.4 Ensurance of Safety ............................................................................................38
1.4.1 Line impedance ............................................................................................................................. 38
1.4.2 Fault Loop impedance ................................................................................................................... 39
1.4.3 Comparison Line and Fault Loop impedances ............................................................................... 40
1.4.4 RCD ................................................................................................................................................ 41
1.4.4.1 RCD trip-out time test .......................................................................................................... 42
1.4.4.2 RCD trip-out current test ..................................................................................................... 42
1.4.4.3 RCD trip-out contact voltage test ........................................................................................ 42
1.4.5 Earth Resistance and Contact Voltage .......................................................................................... 43
1.4.6 Insulation ....................................................................................................................................... 44
1.4.7 Continuity ...................................................................................................................................... 44
2 Measurements on electrical installations in practice .......................................... 45
2.1
Instrument’s general settings ............................................................................45
2.2 Line impedance measurement ...........................................................................47
2.2.1 Background of measurements ...................................................................................................... 48
2.2.2 Line impedance ............................................................................................................................. 49
2.2.2.1 Short circuit line – neutral impedance and prospective short circuit current ..................... 49
2.2.2.2 Short circuit line – line impedance and prospective short circuit current ........................... 50
2.2.2.3 Voltage drop ........................................................................................................................ 51
2.2.3 Exercises ........................................................................................................................................ 52
2.2.3.1 Exercise No. 2.2-1: dU, Z
L-N
and I
PSC
measurement on the supply side ................................ 52
Measuring connection topology ........................................................................................................ 52
Measuring procedure ......................................................................................................................... 52
Expected results ................................................................................................................................. 53
Expected results with a simulated error ............................................................................................ 54
2.2.3.2 Exercise No. 2.2-2: dU, Z
L-N
and I
PSC
measurement on the socket side ................................ 55
Measuring connection topology ........................................................................................................ 55
Measuring procedure ......................................................................................................................... 55
Expected results ................................................................................................................................. 56
Expected results with a simulated error ............................................................................................ 57
2.2.3.3 Exercise No. 2.2-3: dU, Z
L-N
and I
PSC
measurement on the socket side in an IT earthing
system 58
Measuring procedure ......................................................................................................................... 59
Expected results ................................................................................................................................. 60
Expected results with a simulated error ............................................................................................ 61
2.3 Fault loop impedance measurement .................................................................62
2.3.1 Background of measurements ...................................................................................................... 63
2.3.1.1 Fault loop, fault impedance and prospective fault current in TN systems .......................... 63
2.3.1.2 Fault loop, fault impedance and prospective fault current in TT systems........................... 64