IEC 61558-2-4 pdf download

IEC 61558-2-4 pdf download Safety of transformers, reactors, power supply units and similar products for supply voltages up to 1 100 V – Part 2-4: Particular requirements and tests for isolating transformers and power supply units incorporating isolating transformers
14 Heating
This clause of Part 1 is applicable.
15 Short-circuit and overload protection
This clause of Part 1 is applicable.
16 Mechanical strength
This clause of Part 1 is applicable.
17 Protection against harmful ingress of dust, solid objects and moisture
This clause of Part 1 is applicable.
18 Insulation resistance, dielectric strength and leakage current
This clause of Part 1 is applicable.
19 Construction
This clause of Part 1 is applicable except as follows:
Replace 19.1 by the following:
19.1 The input and output circuits shall be electrically separated from each other, and the construction shall be such that there is no possibility of any connection between these circuits, either directly or indirectly, via other conductive parts , except by deliberate action.
Compliance is checked by inspection and measurements, taking Clauses 18 and 26 into consideration.
19.1.1 The insulation between input and output winding(s) shall consist of double or reinforced insulation (rated for the working voltage ) unless the requirements in 1 9.1 .3 are complied with:
In addition, the following applies:
– for class I transformers not intended for connection to the mains supply by means of a plug, the insulation between the input windings and the body connected to earth shall consist of at least basic insulation rated for the input voltage . The insulation between the output windings and the body connected to earth, shall consist of at least basic insulation (rated for the output voltage );
– for class I transformers intended for connection to the mains supply by means of a plug, the insulation between the input windings and the body shall consist of at least basic insulation , and the insulation between the output windings and the body shall consist of at least supplementary insulation (both basic and supplementary insulations rated for the working voltage );
– for class II transformers , the insulation between the input windings and the body shall consist of double or reinforced insulation (rated for the input voltage ). The insulation between the output windings and the body , shall consist of double or reinforced insulation (rated for the output voltage ).
19.1.2 For transformers with intermediate conductive parts (e.g. the iron core) not connected to the body and located between the input and output windings , the following requirements are applicable: