IEC 947-5-1 is part 5 of the general rules which relates to Control- circuit devices and switching elements. ... The Contact Element Form defines the configuration of the contacts and the number of contacts within the switch. e.g. Form Za – both contact elements have the same polarity.
What IEC 947?
Today, conformity with standard IEC 947-2, published in 1989 and reviewed and completed in 1995, can be considered as an « all-risks insurance » guaranteeing a circuit breaker's fitness for use. Quite remarkably all countries, except Japan, have approved this standard.
What is IEC 947 2?
IEC 947-2 defines two categories of circuit breakers: c those of category A for which no short-circuit trip delay is provided. These are generally moulded case circuit breakers such as Compact NS. This requirement is not synonymous with non-discrimination on tripping (see « Cahier Technique » n° 167).