Standards Development

Scope

This document gives general requirements and tests for residual current operated circuit breakers without integral overcurrent protection for household and similar uses, intended to be used in DC systems (hereafter referred to as DC-RCCBs), for rated operational voltages not exceeding 440 V DC and a rated current not exceeding 125 A, intended principally for protection against shock hazard.

These devices are intended to provide fault protection according to IEC 60364-4-41, the exposed conductive parts of the installation being connected to an appropriate earth electrode. In accordance with IEC 60364-4- 42, DC-RCCBs with a rated residual operating current not exceeding 300 mA can also be used to provide protection against fire hazards due to a persistent earth fault current.

DC-RCCBs having a rated residual operating direct current not exceeding 80 mA, are used for fault protection and additional protection in the case of failure of the protective provisions against electric shock, in systems having a rated voltage to earth not exceeding 440 V DC.

This document applies to devices performing simultaneously the functions of detection of the residual current, of comparison of the value of this current with the residual operating value and of opening of the protected circuit when the residual current exceeds this value.

NOTE 1 The requirements for DC-RCCBs are in line with the general safety requirements of IEC 60755-1.

NOTE 2 Installation and selection rules for DC-RCCBs are given in the IEC 60364 series.

DC-RCCBs are intended to be operated by ordinary or uninstructed persons and designed not to require maintenance.

The requirements of this document apply for standard conditions. Additional requirements can be necessary for DC-RCCBs used in locations having severe environmental conditions. They are intended for use in an environment with pollution degree 2.

NOTE 3 For environments with higher pollution degrees, enclosures giving the appropriate degree of protection could be used.

NOTE 4 For DC-RCCBs having a degree of protection higher than IP20 special constructions can be required.

DC-RCCBs are suitable for isolation. They are suitable for use in TN, TT, and, under specific conditions IT systems. Single-pole DC-RCCBs with two current paths are not suitable for use in IT systems.

DC-RCCBs of the general type are resistant to unwanted tripping including the case where surge voltages (as a result of switching transients or induced by lightning) cause loading currents in the installation without occurrence of flashover.

Special precautions (e.g. surge protective devices) can be necessary when excessive overvoltages are likely to occur on the supply side (for example in the case of supply through overhead lines see IEC 60364-44 and IEC 60364‑5-53).

DC-RCCBs of type S are considered to be sufficiently proof against unwanted tripping even if the surge voltage causes a flashover and a follow-on current occurs.

NOTE 5 Surge protective devices installed downstream of DC-RCCBs and connected in common mode can cause unwanted tripping.

This document also applies to DC-RCCBs having more than one rated current, provided that the means for changing from one discrete rating to another is not accessible in normal service and that the rating cannot be changed without the use of a tool.

This document does not apply to DC-RCCBs including batteries

Purpose

n AC systems, residual current devices are used to provide protection against the risk of electric shocks. In IEC 60364 (all parts), residual current devices are used for automatic disconnection of supply in case of fault (see Clause 411 of IEC 60364-4-41:2005+AMD1:2017) and residual current devices with rated residual operating current not exceeding 30 mA are used as additional protection (see 415 of IEC 60364-4- 3 23E/1343/NP 41:2005+AMD1:2017). IEC SC 23E has developed a set of standards for residual current operated protective devices intended to be used in AC systems.

DC systems are used for applications such as photovoltaic installations, data and telecom centers and electric vehicle charging systems. In addition, standards for plugs and socket-outlets for ICT equipment installed in data and telecom centers have been published. Therefore, a reference document for residual current devices intended to be used in DC supply systems is necessary.

Residual current devices for DC systems may be used to provide fault protection (automatic disconnection of supply according to Clause 411 of IEC 60364-4-41:2005+AMD1:2017); they may also be used to provide additional protection. They provide protection against electric shock downstream of the device in DC networks.

This document defines the operating characteristics for residual current operated protective devices for DC systems. Details of how they should be installed to provide the desired level of protection are specified in the various parts of the IEC 60364 series.

The requirements of this standard are in compliance with the Group safety Publication IEC 60755-1.