DB422220_EN - F1
AC-1 zone: Imperceptible
AC-2 zone: Perceptible
AC-3 zone: Reversible effects: muscular contraction
AC-4 zone: Possibility of irreversible effects
AC-4-1 zone: Up to 5% probability of heart fibrillation
AC-4-2 zone: Up to 50% probability of heart fibrillation
AC-4-3 zone: More than 50% probability of heart fibrillation
A curve: Threshold of perception of current
B curve: Threshold of muscular reactions
C1 curve: Threshold of 0% probability of ventricular fibrillation
C2 curve: Threshold of 5% probability of ventricular fibrillation
C3 curve: Threshold of 50% probability of ventricular fibrillation
AC-2 zone: Perceptible
AC-3 zone: Reversible effects: muscular contraction
AC-4 zone: Possibility of irreversible effects
AC-4-1 zone: Up to 5% probability of heart fibrillation
AC-4-2 zone: Up to 50% probability of heart fibrillation
AC-4-3 zone: More than 50% probability of heart fibrillation
A curve: Threshold of perception of current
B curve: Threshold of muscular reactions
C1 curve: Threshold of 0% probability of ventricular fibrillation
C2 curve: Threshold of 5% probability of ventricular fibrillation
C3 curve: Threshold of 50% probability of ventricular fibrillation
Fig. F1 – Zones time/current of effects of AC current on human body when passing from left hand to feet
DB422221_EN - F2
Fig. F2 – Direct contact
DB422222_EN - F3
Fig. F3 – Indirect contact
DB422223 - F4
Fig. F4 – Inherent protection against direct contact by insulation of a 3-phase cable with outer sheath
PB116740 - F5
Fig. F5 – Example of isolation by envelope
PB116741 - F6
Fig. F6 – High sensitivity RCD
DB422224_EN - F7
Fig. F7 – Illustration of the dangerous touch voltage Uc
DB422225_EN - F9
Fig. F9 – Automatic disconnection of supply for TT system
DB422226_EN - F12
Fig. F12 – Automatic disconnection in TN system
DB422227_EN - F14
Fig. F14 – Disconnection by circuit breaker for a TN system
DB422228_EN - F15
Fig. F15 – Disconnection by fuses for a TN system
PB116742 - F16
Fig. F16 – Phases to earth insulation monitoring device obligatory in IT system
DB422229_EN - F17
Fig. F17 – Fault current path for a first fault in IT system
DB422230_EN - F18
Fig. F18 – Circuit breaker tripping on double fault situation when exposed-conductive-parts are connected to a common protective conductor
DB422231_EN - F20
Fig. F20 – Application of RCDs when exposed-conductive-parts are earthed individually or by group on IT system
DB422232 - F21
Fig. F21 – Low-voltage supplies from a safety isolating transformer
DB422233 - F22
Fig. F22 – Safety supply from a class II separation transformer
DB422234_EN - F23
Fig. F23 – Principle of class II insulation level
DB422235_EN - F24
Fig. F24 – Protection by out-of arm’s reach arrangements and the interposition of non-conducting obstacles
DB422236_EN - F25
Fig. F25 – Equipotential bonding of all exposed-conductive-parts simultaneously accessible
DB422237_EN - F26
Some tests have shown that a very low leakage current (a few mA) can evolve and, from 300 mA, induce a fire in humid and dusty environment.
Fig. F26 – Origin of fires in buildings
DB422239_EN - F29
Fig. F29 – Distribution circuits
DB422240_EN - F30
Fig. F30 – Separate earth electrode
DB422241 - F31
Fig. F31 – Circuit supplying socket-outlets
DB422242_EN - F32
Fig. F32 – Fire-risk location
DB422243 - F33
Fig. F33 – Unearthed exposed conductive parts (A)
DB422244_EN - F34
Fig. F34 – Total discrimination at 2 levels
DB422245_EN - F35
Fig. F35 – Total discrimination at 2 levels
DB422246_EN - F36
Fig. F36 – Total discrimination at 3 or 4 levels
DB422247_EN - F37
Fig. F37 – Typical 3-level installation, showing the protection of distribution circuits in a TT-earthed system. One motor is provided with specific protection
DB422248_EN - F38
Notes:
- The TN scheme requires that the LV neutral of the MV/LV transformer, the exposed conductive parts of the substation and of the installation, and the extraneous conductive parts in the substation and installation, all be earthed to a common earthing system.
- For a substation in which the metering is at low-voltage, a means of isolation is required at the origin of the LV installation, and the isolation must be clearly visible.
- A PEN conductor must never be interrupted under any circumstances.
Control and protective switchgear for the several TN arrangements will be:
- 3-pole when the circuit includes a PEN conductor,
- Preferably 4-pole (3 phases + neutral) when the circuit includes a neutral with a separate PE conductor.
- The TN scheme requires that the LV neutral of the MV/LV transformer, the exposed conductive parts of the substation and of the installation, and the extraneous conductive parts in the substation and installation, all be earthed to a common earthing system.
- For a substation in which the metering is at low-voltage, a means of isolation is required at the origin of the LV installation, and the isolation must be clearly visible.
- A PEN conductor must never be interrupted under any circumstances.
Control and protective switchgear for the several TN arrangements will be:
- 3-pole when the circuit includes a PEN conductor,
- Preferably 4-pole (3 phases + neutral) when the circuit includes a neutral with a separate PE conductor.
Fig. F38 – Implementation of the TN system of earthing
DB422249 - F39
Fig. F39 – Calculation of L max. for a TN-earthed system, using the conventional method
DB422240_EN - F45
Fig. F45 – Separate earth electrode
DB422241 - F46
Fig. F46 – Circuit supplying socket-outlets
DB422242_EN - F47
Fig. F47 – Fire-risk location
DB422250_EN - F48
Fig. F48 – Circuit breaker with low-set instantaneous magnetic tripping
DB422251_EN - F49
Fig. F49 – RCD protection on TN systems with high earth-fault-loop impedance
DB422252_EN - F50
Fig. F50 – Improved equipotential bonding
DB422253_EN - F52
Fig. F52 – Positions of essential functions in 3-phase 3-wire IT-earthed system
DB422254 - F53
Fig. F53 – Non-automatic (manual) fault location
DB422255_EN - F54
Fig. F54 – Fixed automatic fault location
DB422256 - F55
Fig. F55 – Automatic fault location and insulation-resistance data logging
DB422257_EN - F56
Fig. F56 – Calculation of Lmax. for an IT-earthed system, showing fault-current path for a double-fault condition
DB422267 - F58
Fig. F58 – Circuit supplying socket-outlets
DB422258_EN - F59
Fig. F59 – Fire-risk location
DB422259_EN - F60
Fig. F60 – A circuit breaker with low-set instantaneous magnetic trip
DB422251_EN - F61
Fig. F61 – RCD protection
DB422252_EN - F62
Fig. F62 – Improved equipotential bonding
DB422260 - F63
Fig. F63 – The principle of RCD operation
DB422261_EN - F67
Fig. F67 – Standardized 0.5 µs/100 kHz current transient wave
DB422262_EN - F68
Fig. F68 – Standardized 1.2/50 µs voltage transient wave
DB422263_EN - F69
Fig. F69 – Standardized current-impulse wave 8/20 µs
DB422264 - F73
L = twice the diameter of the magnetic ring core
Fig. F73 – Means of reducing the ratio IΔn/Iph (max.)
DB422265 - F75
Fig. F75 – Residual current circuit breakers (RCCBs)
PB116752 - F76
Fig. F76 – Example of a carbonized connection
PB116753 - F77
Fig. F77 – Illustration of a resistive short circuit
PB116754 - F79
Fig. F79 – Example of an arc fault detector for residential installations in Europe
PB116755 - F80
Fig. F80 – Typical waveform of electric arc. Voltage (black) and current (green)
