AS ISO 14990.2:2022 – Earth-moving machinery – Electrical safetyof machines utilizing electric drives andrelated components and systems Part 2: Particular requirements for externally-powered machines.
— devices for the suppression olovervoltages due to switching surges shall be connected across the terminals of all equipment requiring such protection.
10 Electric power source
The requirements of ISO 14990-1:2016, Clause 10 shall apply except as modified by this clause.
NOTE Externally-powered (mains-connected) EMMs include machines powered by external dedicated generators, which in turn include any off-board electric power generation equipment intended to provide power to the machine.
10.1 Incoming supply conductor terminations
Where a neutral conductor Is used It shall be clearly indicated In the technical documentation of the machine, such as in the installation diagram and in the circuit diagram, and a separate insulated terminal, labelled N” in accordance with 16.1, shall be provided for the neutral conductor.
There shall be no connection between the neutral conductor and the protective bonding circuit inside the electrical equipment nor shall a combined PEN terminal be provided.
Exception: a connection may be made between the neutral terminal and the PE terminal at the point of the connection of the power supply to the machine for TN-C systems.
TN, TT, and IT systems are defined by IEC 60364-1, which covers voltages up to 1 000 V AC and 1 500 V DC This document extends the range of application for TN, TT. and IT systems to 36kV AC or DC.
All terminals for the incoming supply connection shall be clearly identified in accordance with IEC 60445 and 16.). For the identification of the external protective conductor terminal, see 10.3.
The following practices are recommended:
— the electrical equipment of EMM should, if practicable, be connected to a single incoming supply;
— if one or more additional supplies are necessary for certain parts of the equipment (e.g. equipment that operates at a different voltage), those supplies should be derived, as far as is practicable, from devices such as transformers or converters forming part of the electrical equipment of the machine;
— unless a plug is provided with the machine for the connection to the supply, the supply conductors should be terminated at the supply disconnecting device (for some systems, such as cable drum, this Is not practical. but there should be a disconnecting device at the closest practical point to the power source).
10.2 Terminal for connection to the external protective earthing system
A terminal shall he provided near the phase conductor terminals for each incoming supply. Depending upon the supply distribution system, this terminal shall be for connection of the EMM to the external protective earthing system or to the external protective conductor.
The terminal shall be sized to accommodate an external protective copper conductor with a cross-sectional area given by Table I. If an external protective conductor of a material other than copper is used, the terminal size shall be selected accordingly see also ISO 14990-1:2016.
At each incoming supply point, the terminal for connection of the external protective earthing system or the external protective conductor shall be marked or labelled with the letters PE (see IEC 60445).
10.3 Protection against unauthorized, inadvertent and/or mistaken connection
Devices which are described In ISO 14990•1:2016, 10.2 and 10.3. and which are located outside an enclosed electrical operating area shall be equipped with means to secure them in the OFF (disconnected) position (e.g. by provisions for padlocking or trapped key interlocking). Such a lock-oil arrangement shall prevent remote as well as local reconnection.
If a non-lockable disconnecting device e.g. withdrawahle fuse-links or withdrawahle links) is provided. other means of protection against reconnection (e.g. warning labels iii accordance with 16.1) may be provided.
However, when a plug/socket combination according to ISO 149904:2016, 11.10.5 e) Is so positioned that it can be kept under the immediate supervision of the person carrying out the work, means for securing in the disconnected state need not be provided.
11 WIring
The requirements of ISO 14990-1:2016, Clause 11 shall apply except as modified by this clause.
11.1 Flexible cables
For high-voltage equipment, each flexible cable (e.g. trailing cable) for the high voltage power supply to the electrical equipment of EMM shall contain a protective conductor (see ISO 14990-1:2016, The cross-sectIonal area of the protective conductor shall comply with Table 1, A protective conductor of cross-sectional area least 25 mm2 may be divided into several conductors of equal cross-sectional areas within the flexible cable.