IEC 60947-4-3:2020 pdf free download – Low-voltage switchgear and controlgear
8.1.1General
Subclause 8.1.1 of IEC 60947-1:2020 applies with the following addition.
Measures shall be provided to reduce the likelihood of injury and property damage，underinstallation，maintenance，normal operation conditions，abnormal operation conditions andreasonably foreseeable misuses.The requirements of this document are intended to providethese measures.
Protection against hazards caused by the electronic circuits shall be maintained under normaland single fault conditions, as specified in this document.
Components used in the construction of the equipment, compliant with a relevant lEC productstandard, do not require separate evaluation. Components or assemblies of components, forwhich no relevant product standard exists,shall be tested according to the requirements ofthis document. Where mechanical switching devices are used,they should meet therequirements of their own IEC product standard，and the additional requirements of thisdocument.
Where the product is intended to be used together with specific auxiliary equipment anddedicated wiring accessories，the safety evaluation and test shall include this auxiliaryequipment and accessories unless it can be shown that it does not affect the safety of anyequipment.
The accessible part of the device and especially the operating means shall not present sharpedges and corners which can injure the operator.
The user manual shall give details of all safety-relevant adjustments intended for the user.Clear warning shall be provided in the user’manual where adjustment could lead to ahazardous situation.
Annex o of lEC 60947-1:2020 should be considered carefully especially for substitution orreduction in use of hazardous substances or if not possible for providing measures to preventemission and contact with them.
NOTE The future publication lEC TS 63058 will give the method for assessing the environmental impact ofswitchgear and controlgear.
When tests on the equipment or on sections taken from the equipment are used, parts ofinsulating materials necessary to retain current-carrying parts in position shall conform to theglow-wire tests in 9.2.2.1 of IEC 60947-1:2020 at a test temperature of 850°℃.
8.1.2.3Test based on flammability category
Subclause 8.1.2.3 of lEC 60947-1:2020 applies.
8.1.3current-carrying parts and their connectionsSubclause 8.1.3 of IEC 60947-1:2020 applies.
Wiring that is subject to movement or flexing during its intended use, or during mechanicalmaintenance,such as wiring from a stationary part to a part mounted on a hinged cover ordoor, shall be routed and secured so that the wire is not damaged during opening and closingof the door or cover.
8.1.4Clearances and creepage distances
Subclause 8.1.4 of lEC 60947-1:2020 applies with the following additions.
Clearance and creepage distances within the circuits sourced from limited energy sources asdefined in 8.1.14, including those on printed wiring boards(PWBs), are not required to complywith the requirements of the above subclause.
Where SELV and PELV circuits are accessible, they shall be separated from other hazardous-live-part according to the requirements of AnnexL for protective impedance in addition toAnnex N of lEC 60947-1:2020.
NOTE1 lf some circuits are only accessible under maintenance or similar conditions, they can, depending on therisk level (severity of harm and the probability of occurrence), be considered under normal service conditions(see 6.1), and use only basic insulation.Accessible parts can be determined using test probes according toiEC61032.
NOTE 2 The nature of a semiconductor makes it unsuitable for use for isolation purposes.