Safety of Small Power Transformers, Power Supply Units and Similar - Part 2-8: Particular Requirements for Bell and Chime Transformers
|Publication Date:||1 August 1998|
|ICS Code (Transformers. Reactors):||29.180|
This international standard deals with all aspects of safety such as electrical, thermal and mechanical.
This part 2-8 of IEC 61558 applies to fixed, single-phase, air-cooled (natural or forced), independant or associated safety isolating transformers for bell and chimes, having a rated supply voltage not exceeding 250 V a.c., a rated frequency not exceeding 500 Hz, a rated output not exceeding 100 VA.
The no-load output voltage shall not exceed 33 V a.c. or 46 V ripple free d.c. and the rated output voltage shall not exceed 24 V a.c. or 33 V ripple free d.c.
Bell and chime transformers are generally intended to supply domestic sound signalling equipment and other similar devices where the load is applied for short periods of time.
NOTE 1 - A partial load may be applied for illumination purposes.
This standard applies to special safety isolating transformers (transformer for bell and chime) which are used where double or reinforced insulation between circuits is required by the installation rules or by the appliance specification.
This standard is applicable to dry-type transformers. The windings may be encapsulated or non-encapsulated.
NOTE 2 - Attention is drawn to the fact that for transformers intended to be used in tropical countries special requirements may be necessary.
This standard also applies to transformers incorporating electronic circuits. This standard does not apply to external circuits and their components intended to be connected to the input and output terminals or socket-outlets of the transformer.