IEC 60364-5-56-2018 pdf free.Low-voltage electrical installations – Part 5-56: Selection and erection of electrical equipment – Safety services.
560.4.1 An electrical supply system for safety services is either:
– a non-automatic supply system, the starting of which is initiated by an operator, or
– an automatic supply system, the starting of which is independent of an operator.
An automatic supply system is classified as follows,according to the maximum changeovertime:
class A – no-break: an automatic supply system which can ensure a continuous supply within specified conditions during the period of transition，for example as regardsvariations in voltage and frequency;
class B- very short break: an automatic supply system available within 0,15 s;
– class C- short break: an automatic supply system available within 0,5 s;
– class D – average break: an automatic supply system available within 5 s;
– class E- medium break: an automatic supply system available within 15 s;
– class F- long break: an automatic supply system available in more than 15 s.
560.4.2 The essential equipment for safety services shall be within the specified classaccording to 560.4.1 in order to maintain the specified operation.
560.5 General
560.5.1 Safety services may be required to operate at all relevant times including duringmain and local supply failure and through fire conditions. To meet these requirements,specific sources, equipment,circuits and wiring are necessary. Some applications also haveparticular requirements,as in 560.5.2 and 560.5.3.
560.5.2 For safety services required to operate in fire conditions，the following additionalconditions shall be fulfilled:
one or more electrical sources for safety services shall be provided to maintain a supply ofadequate duration，except for preferential circuits and al equipment of safety servicesshall be provided，either by construction or by erection，with fire protection ensuringnormal operation in fire conditions of adequate duration.
NOTE 1 Equipment includes for example，power sources，feeder conductors, cable management systems,junction boxes.
NOTE 2 The electrical source for safety services is generally additional to the normal supply source, for examplethe public supply network.
NOTE 3 Local legislation can apply.
560.5.3 An lT system is preferred where non-disconnection on the first fault is required. In lTsystems for safety services，insulation monitoring devices shall be provided which give anaudible and visible indication in the event of a first fault.
560.5.4 A failure in the control or bus systems (control technology) of the non-safetyservices installation shall not adversely affect the proper function of safety services. Thisapplies to control or bus systems of different safety services as well.
560.6 Electrical sources for safety services
560.6.1 The following electrical sources for safety services are recognized:
storage batteries;
primary cells;
generator sets independent of the normal supply;
a separate feeder of the supply network that is effectively in dependent of the normalfeeder.
560.6.2 The electrical source for safety services shall be installed as fixed equipment and insuch a manner that it cannot be adversely affected by failure of the normal source.
560.6.3 The electrical source for safety services shall be installed in a suitable location andbe accessible only to skilled or instructed persons (BA5 or BA4).Electrical sources for safetyservices should be segregated from other sources.
Safety services and sources shall be designed and located so as to minimize hazards thatcould cause fire, flooding, freezing，vandalism and other adverse conditions and impact theavailability of the electrical supply.
NOTESee Annex G for guidance.
560.6.4 The location of the electrical source for safety services shall be properly andadequately ventilated so that exhaust gases,smoke or fumes from the safety source cannotpenetrate areas occupied by persons.
560.6.5 Separate，independent feeders from a supply network shall not serve as electricalsources for safety services unless assurance can be obtained that the two supplies areunlikely to fail concurrently.
560.6.6 The electrical source for safety services shall have sufficient capability to supply itsrelated safety service.
560.6.7 An electrical source for safety services may, in addition, be used for purposes otherthan safety services，provided the availability for safety services is not thereby impaired.Afault occurring in a circuit for purposes other than safety services shall not cause theinterruption of any circuit for safety services.
560.6.8 There are special requirements for safety sources not capable of operation inparallel.IEC 60364-5-56 pdf download.