This standard specifies requirements for semicondutor rectifiers, diodes and thyristors, convertor* transformers and reactors, and convertor equipments and assemblies together with tolerances on rated values and conditions, and performance requirements and application information. In addition, letter symbols and definitions are provided for terms used in conjunction with such devices and equipments.ApplicationThis standard applies to static power convertors of the line- or machine-commutated type for conversion from a.c. to d.c. or from d.c. to a.c., i.e. rectifiers, inverters and convertors embodying both modes of operation. It applies also to convertors for control of alternating voltage and convertors in which the commutating voltage is supplied by the load circuit, e.g. a resonating load.The standard is restricted to convertors with semiconductor rectifier diodes, reverse blocking triode thyristors or a combination of these, but it may also be applied for convertors with bidirectional thyristors in so far as applicable. The term 'thyristor' is used in the standard as an abbreviation for reverse blocking triode thyristor.The standard does not apply to convertors in which the commutating voltage is supplied by internal sources, e g. capacitors, frequency convertors, convertors used in telecommunication apparatus other than for power supplied to such equipment, to auxiliaries of measuring instruments, or system control equipments for control of static power convertors.Special kinds of convertors, e.g. convertors for adjustable speed d.c. motor drives, power convertors for electric traction, convertors for control of alternating voltage, self-commutated inverters, d.c. to d.c. convertors, etc, are not covered by this standard.