IEC 60364-4-44-2018 pdf free

IEC 60364-4-44-2018 pdf free.Low-voltage electrical installations – Part 4-44: Protection for safety – Protection against voltage disturbances and electromagnetic disturbances.”
441 (Vacant)
442 Protection of low-voltage installations against temporary overvoltages due to earth faults in the high-voltage system and due to faults in the low- voltage system
442.1 FIeld of application
The rules of this clause provide requirements for the safety of low-voltage installation in the event of
— a fault between the high-voltage system and earth in the transformer substation that supplies the low-voltage installation,
— a loss of the supply neutral in the low-voltage system,
— a short-circuit between a line conductor and neutral,
— an accidental earthing of a line conductor of a low-voltage IT-system.
The requirements for the earthing arrangement at the transformer substation are given in
IEC 61936-1.
442.1 .1 General requirements
As Clause 442 covers faults between a high-voltage line and the earth in the HV/LV substation, it gives rules for the designer and installer of the substation. It is necessary to have the following information concerning the high-voltage system:
— quality of the system earthing;
— maximum level of earth fault current;
— resistance of the earthing arrangement.
The following subclauses consider four situations as proposed in 442.1, which generally cause the most severe temporary overvoltages such as defined in IEC 60050-604:
— fault between the high-voltage system(s) and earth (see 442.2);
— loss of the neutral in a low-voltage system (see 442.3);
— accidental earthing of a low-voltage IT system (see 442.4);
— short-circuit in the low-voltage installation (see 442.5).
442.1.2 Symbols
In Clause 442 the following symbols are used (see Figure 44.A1):
part of the earth fault current in the high-voltage system that flows through the earthing arrangement of the transformer substation.
RE resistance of the earthing arrangement of the transformer substation.
RA resistance of the earthing arrangement of the exposed-conductive-parts of the equipment of the low-voltage installation.
R8 resistance of the earthing arrangement of the low-voltage system neutral, for lowvoltage systems in which the earthing arrangements of the transformer substation and of the low-voltage system neutral are electrically independent.IEC 60364-4-44 pdf download.