scope:

Scope and object

In addition to the general requirements of IEC 60077-2, this part of IEC 60077 gives the rules for circuit-breakers, the main contacts of which are to be connected to d.c. power and/or auxiliary circuits. The nominal voltage of these circuits does not exceed 3 000 V d.c. according to IEC 60850.

This part of IEC 60077, together with IEC 60077-2, states specifically

a) the characteristics of the circuit-breakers;

b) the service conditions with which circuit-breakers have to comply with reference to

-operation and behaviour in normal service;

- operation and behaviour in the case of short circuit;

- dielectric properties;

c) the tests for confirming the compliance of the components with the characteristics under the service conditions and the methods to be adopted for these tests;

d) the information to be marked on, or given with, the circuit breaker.

NOTE 1 Circuit-breakers which are dealt with in this part of IEC 60077 may be provided with devices for automatic opening under predetermined conditions other than those of over-current, for example, under-voltage and reversal of power current. This part of IEC 60077 does not deal with the verification of operation under such predetermined conditions.

NOTE 2 The incorporation of electronic components or electronic sub-assemblies into electrotechnical components is now common practice.

Although this standard is not applicable to electronic equipment, the presence of electronic components does not provide a reason to exclude such electrotechnical components from the scope.

Electronic sub-assemblies included in circuit-breakers should comply with the relevant standard for electronics (IEC 60571).

NOTE 3 Certain of these rules may, after agreement between the user and the manufacturer, be used for electrotechnical components installed on vehicles other than rail rolling stock such as mine locomotives, trolleybuses, etc. In this case, particular additional requirements may be necessary.

This standard does not cover

a) multi-connection of electro-technical components to achieve a particular duty;

b) industrial circuit-breakers which have to comply with IEC 60947-2;

c) d.c. circuit-breakers for fixed installations which have to comply with IEC 61992-2.

For b) and c), in order to ensure satisfactory operation, this standard should be used to specify only the particular requirements for rolling stock. In such cases, a specific document should state the additional requirements with which the industrial or fixed installations circuits breakers are to comply, for example:

- either to be adapted (for example, for control voltage, environmental conditions, etc.);

- or to be installed and used in such a way that they do not have to endure specific rolling stock conditions;

- or to be additionally tested to prove that these components can withstand satisfactorily the rolling stock conditions.