UNE-EN IEC 60077-3:2021

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 connected to DC power and/or auxiliary circuits. The nominal voltage of these circuits does not exceed 3 000 V DC 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 complies 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 document are provided with devices for automatic opening under predetermined conditions other than those of overcurrent, for example, under-voltage and reversal of power current. This document 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 document 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 complies with the relevant document for electronics (IEC 60571).

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

This document does not cover:

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

b) industrial circuit-breakers which complies with IEC 60947-2;

c) DC circuit-breakers for fixed installations which complies with IEC 61992-2.

For b) and c), in order to ensure satisfactory operation, this document is used to specify only the particular requirements for rolling stock. In such cases, a specific document states the additional requirements with which the industrial or fixed installations circuits breakers 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.