IEC 61558-2-19:2000-pdf download-Safety of power transformers, power supply units and similar devices – Part 2-1 9: Particular requirements for perturbation attenuation transformers.
1 0 Change of input voltage setting This clause of part 1 is applicable except as follows: Transformers with more than one rated supply voltage are not allowed. Transformers provided with a device for adjusting the input connections (e.g. tappings) to suit supply voltages are also not allowed. 1 1 Output voltage and output current under load This clause of part 1 is applicable except as follows: 1 1 .1 Replacement of the first two paragraphs: When the transformer is connected to the rated supply voltage at rated frequency and the secondary loaded by the rated output at cos ϕ = 1 , the output voltage shall not differ from the rated value by more than 3 %. 1 2 No-load output voltage This clause of part 1 is applicable except as follows: Addition: 1 2.1 01 The no-load output voltage shall not exceed: – 500 V a.c. or 708 V ripple free d.c. for perturbation attenuation isolating transformers; – 50 V a.c. or 1 20 V ripple free d.c. for perturbation attenuation safety isolating trans- formers, under any circumstances, even when independent output windings which are not intended to be connected in series are connected in series. 1 2.1 02 The difference between the no-load output voltage and the output voltage under load shall not be excessive. Compliance with the requirements of 1 2.1 01 and 1 2.1 02 is checked by measuring the no-load output voltage when the transformer, at ambient temperature, is connected to the rated supply voltage at rated frequency.
1 9.1 .2 For transformers with intermediate metal parts (e.g. the iron core) not connected to the body and located between the input and output windings, the insulation between the intermediate metal part and the input windings or between the intermediate metal part and the output windings, shall consist of at least basic insulation. NOTE An intermediate metal part which is not separated from the input or output windings or the body by at least basic insulation, is considered to be connected to the relevant part(s). In addition, the following applies: – for class I transformers, the insulation between the input and output windings via the intermediate metal part shall consist of double or reinforced insulation; – for class II transformers, the insulation between the input and output windings via the intermediate metal part shall consist of double or reinforced insulation; the insulation between the input windings and the body, and between the output windings and the body, via the intermediate metal part shall consist of double or reinforced insulation. 1 9.1 .3 Class I transformers shall not have protective screening between input and output windings. 1 9.1 .4 Transformers shall not be provided with capacitors which electrically connect input and output circuits.