Страница 10: ДСТУ EN 60204-1:2014. Safety of machinery - Electrical equipment of machines - Part 1: General requirements (61446)

The joints or gaskets of doors, lids, covers and enclosures shall withstand the chemical effects of the aggressive liquids, vapours, or gases used on the machine. The means provided to maintain the degree of protection of an enclosure on doors, lids and covers that require opening or removal for operation or maintenance shall:

• be securely attached to either the door/cover or the enclosure;

• not deteriorate due to removal or replacement of the door or the cover, and so impair the degree of protection.

Where openings in enclosures are provided (for example, for cable access), including those towards the floor or foundation or to other parts of the machine, means shall be provided to ensure the degree of protection specified for the equipment. Openings for cable entries shall be easily re-opened on site. A suitable opening may be provided in the base of enclosures within the machine so that moisture due to condensation can drain away.

There shall be no opening between enclosures containing electrical equipment and compartments containing coolant, lubricating or hydraulic fluids, or those into which oil, other liquids, or dust can penetrate. This requirement does not apply to electrical devices specifically designed to operate in oil (for example electromagnetic clutches) nor to electrical equipment in which coolants are used.

Where there are holes in an enclosure for mounting purposes, means may be necessary to ensure that after mounting, the holes do not impair the required protection.

Equipment that, in normal or abnormal operation, can attain a surface temperature sufficient to cause a risk of fire or harmful effect to an enclosure material shall:

• be located within an enclosure that will withstand, without risk of fire or harmful effect, such temperatures as can be generated; and

• be mounted and located at a sufficient distance from adjacent equipment so as to allow safe dissipation of heat (see also 11.2.3); or

• be otherwise screened by material that can withstand, without risk of fire or harmful effect, the heat emitted by the equipment.

NOTE A warning label in accordance with 16.2.2 may be necessary.

Doors in gangways and for access to electrical operating areas shall:

• be at least 0,7 m wide and 2,1 m high;

• open outwards;

• have a means (for example panic bolts) to allow opening from the inside without the use of a key or tool.

Enclosures which readily allow a person to fully enter shall be provided with means to allow escape, for example panic bolts on the inside of doors. Enclosures intended for such access, for example for resetting, adjusting, maintenance, shall have a clear width of at least 0,7 m and a clear height of at least 2,1 m.

In cases where:

equipment is likely to be live during access; and conducting parts are exposed, the clear width shall be at least 1,0 m. In cases where such parts are present on both sides of the access way, the clear width shall be at least 1,5 m.

NOTE These dimensions are derived from ISO 14122 series.

11. Conductors and cables

    1. General requirements

Conductors and cables shall be selected so as to be suitable for the operating conditions (for example voltage, current, protection against electric shock, grouping of cables) and external influences (for example ambient temperature, presence of water or corrosive substances, mechanical stresses (including stresses during installation), fire hazards) that can exist.

NOTE Further information is given in CENELEC HD 516 S2.

These requirements do not apply to the integral wiring of assemblies, subassemblies, and devices that are manufactured and tested in accordance with their relevant IEC standard (for example IEC 60439-1).

in general, conductors shall be of copper. Where aluminium conductors are used, the cross- sectional area shall be at least 16 mm2.

To ensure adequate mechanical strength, the cross-sectional area of conductors should not be less than as shown in Table 5. However, conductors with smaller cross-sectional areas or other constructions than shown in Table 5 may be used in equipment provided adequate mechanical strength is achieved by other means and proper functioning is not impaired.

NOTE Classification of conductors is given in Table D.4.

Table 5 - Minimum cross-sectional areas of copper conductors

NOTE All cross-sections in mm².

¹> Except special requirements of individual standards, see also 12.1.

Class 1 and class 2 conductors are primarily intended for use between rigid, non-moving parts.

All conductors that are subject to frequent movement (for example one movement per hour of machine operation) shall have flexible stranding of class 5 or class 6.

The types of insulation include (but are not limited to):

• polyvinyl chloride (PVC);

• rubber, natural and synthetic;

• silicone rubber (SiR);

• mineral;

• cross-linked polyethylene (XLPE);

• ethylene propylene compound (EPR).

Where the insulation of conductors and cables (for example PVC) can constitute hazards due to the propagation of a fire or the emission of toxic or corrosive fumes, guidance from the cable supplier should be sought. It is important to give special attention to the integrity of a circuit having a safety-related function.

The insulation of cables and conductors used, shall be suitable for a test voltage:

• not less than 2 000 V a.c. for a duration of 5 min for operation at voltages higher than 50 V a.c. or 120 V d.c., or

• not less than 500 V a.c. for a duration of 5 min for PELV circuits (see IEC 60364-4-41, class III equipment).

The mechanical strength and thickness of the insulation shall be such that the insulation cannot be damaged in operation or during laying, especially for cables pulled into ducts.

The current-carrying capacity depends on several factors, for example insulation material, number of conductors in a cable, design (sheath), methods of installation, grouping and ambient temperature.

NOTE 1 Detailed information and further guidance can be found in IEC 60364-5-52, in some national standards or given by the manufacturer.

One typical example of the current-carrying capacities for PVC insulated wiring between enclosures and individual items of equipment under steady-state conditions is given in Table 6.

NOTE 2 For specific applications where the correct cable dimensioning can depend on the relationship between the period of the duty cycle and the thermal time constant of the cable (for example starting against high-inertia load, intermittent duty), the cable manufacturer should be consulted.

Table 6 - Examples of current-carrying capacity (/_z) of PVC insulated copper conductors or cables under steady-state conditions in an ambient air temperature of +40 °С for different methods of installation

NOTE 1 The values of the current-carrying capacity of Table 6 are based on:

• one symmetrical three-phase circuit for cross-sectional areas 0,75 mm2 _and greater;

• one control circuit pair for cross-sectional areas between 0,2 mm² and 0,75 mm².

Where more loaded cables/pairs are installed, derate the values of Table 6 in accordance with Tables D.2 or D.3.

NOTE 2 For ambient temperatures other than 40 °С, correct the current-carrying capacities by using values given in Table D.1.

NOTE 3 These values are not applicable to flexible cables wound on drums (see 12.6.3).

NOTE 4 For the current-carrying capacities of other cables, see IEC 60364-5-52.

The voltage drop from the point of supply to the load shall not exceed 5 % of the nominal voltage under normal operating conditions. In order to conform to this requirement, it can be necessary to use conductors having a larger cross-sectional area than that derived from Table 6.

Flexible cables shall have Class 5 or Class 6 conductors.

NOTE 1 Class 6 conductors have smaller diameter strands and are more flexible than Class 5 conductors (see Table D.4).

Cables that are subjected to severe duties shall be of adequate construction to protect against:

• abrasion due to mechanical handling and dragging across rough surfaces;

• kinking due to operation without guides;

• stress resulting from guide rollers and forced guiding, being wound and re-wound on cable drums.

NOTE 2 Cables for such conditions are specified in relevant national standards.

NOTE 3 The operational life of the cable will be reduced where unfavourable operating conditions such as high tensile stress, small radii, bending into another plane and/or where frequent duty cycles coincide.

The cable handling system of the machine shall be so designed to keep the tensile stress of the conductors as low as is practicable during machine operations. Where copper conductors are used, the tensile stress applied to the conductors shall not exceed 15 N/mm² of the copper cross-sectional area. Where the demands of the application exceed the tensile stress limit of 15 N/mm², cables with special construction features should be used and the allowed maximal tensile stress should be agreed with the cable manufacturer.

The maximum stress applied to the conductors of flexible cables with material other than copper shall be within the cable manufacturer’s specification.

NOTE The following conditions affect the tensile stress on the conductors:

• acceleration forces;

• speed of motion;

• dead (hanging) weight of the cables;

• method of guiding;

• design of cable drum system.

Cables to be wound on drums shall be selected with conductors having a cross-sectional area such that, when fully wound on the drum and carrying the normal service load, the maximum allowable conductor temperature is not exceeded.

For cables of circular cross-sectional area installed on drums, the maximum current-carrying capacity in free air should be derated in accordance with Table 7 (see also Clause 44 of IEC 60621-3).

NOTE The current-carrying capacity of cables in free air can be found in manufacturers’ specifications or in relevant national standards.

Table 7 - Derating factors for cables wound on drums

Conductor wires, conductor bars and slip-ring assemblies shall be installed or enclosed in such a way that, during normal access to the machine, protection against direct contact is achieved by the application of one of the following protective measures:

• protection by partial insulation of live parts, or where this is not practicable;

• protection by enclosures or barriers of at least IP2X (see 412.2 of IEC 60364-4-41).

Horizontal top surfaces of barriers or enclosures that are readily accessible shall provide a degree of protection of at least IP4X (see 412.2.2 of IEC 60364-4-41).

Where the required degree of protection is not achieved, protection by placing live parts out of reach in combination with emergency switching off in accordance with 9.2.5.4.3 shall be applied.

Conductor wires and conductor bars shall be so placed and/or protected as to:

• prevent contact, especially for unprotected conductor wires and conductor bars, with conductive items such as the cords of pull-cord switches, strain-relief devices and drive chains;

• prevent damage from a swinging load.

Where conductor wires, conductor bars and slip-ring assemblies are installed as part of the protective bonding circuit, they shall not carry current in normal operation. Therefore, the protective conductor (PE) and the neutral conductor (N) shall each use a separate conductor wire, conductor bar or slip-ring. The continuity of the protective conductor circuit using sliding contacts shall be ensured by taking appropriate measures (for example, duplication of the current collector, continuity monitoring).

Protective conductor current collectors shall have a shape or construction so that they are not interchangeable with the other current collectors. Such current collectors shall be of the sliding contact type.

Removable current collectors having a disconnector function shall be so designed that the protective conductor circuit is interrupted only after the live conductors have been disconnected, and the continuity of the protective conductor circuit is re-established before any live conductor is reconnected (see also 8.2.4).

Clearances between the respective conductors, and between adjacent systems, of conductor wires, conductor bars, slip-ring assemblies and their current collectors shall be suitable for at least a rated impulse voltage of an overvoltage category III in accordance with IEC 60664-1.

Creepage distances between the respective conductors, between adjacent systems of conductor wires, conductor bars and slip-ring assemblies, and their current collectors shall be suitable for operation in the intended environment, for example open air (IEC 60664-1), inside buildings, protected by enclosures.

In abnormally dusty, moist or corrosive environments, the following creepage distance requirements apply: