---

• Method B1: using conduits (3.7) and cable trunking systems (3.5) for holding and protecting conductors or single core cables;

• Method B2: same as B1 but used for multicore cables;

• Method C: multicore cables installed in free air, horizontal or vertical without gap

between cables on walls;

• Method E: multicore cables in free air, horizontal or vertical laid on open cable trays (3.4).

IEC 1393/05

Conductors/single core cables in conduit and cable trunking systems

Cables in conduit and cable trunking systems

Cables on walls

Cables on open cable trays

Figure D.1 - Methods of conductor and cable installation
independent of number of conductors/cables

D.1.3 Grouping

Where more loaded conductors in cables or conductor pairs are installed, derate the values of J_z, given in Table 6 or by the manufacturer in accordance with Tables D.2 or D.3.

NOTE Circuits with I_b< 30 % of I_z need not be derated.

Table D.2 - Derating factors from /_zfor grouping

Table D.3 - Derating factors from 7_Zfor multicore cables up to 10 mm²

D.1.4 Classification of conductors

Table D.4 - Classification of conductors

NOTE Derived from IEC 60228.

D.2 Co-ordination between conductors and protective devices providing overload protection

F

Design current I_b

igure D.2 illustrates the relationship between the parameters of conductors and the parameters of protective devices providing overload protection.

Current carrying capacity l_z

1,45 x/₂

Parameters of
conductors

Parameters of
protective devices

Acceptable range for
tripping current І2

Nominal current or current setting I_n

Figure D.2 - Parameters of conductors and protective devices

Correct protection of a cable requires that the operating characteristics of a protective device (for example overcurrent protective device, motor overload protective device) protecting the cable against overload satisfy the two following conditions:

where

/_b is the current for which the circuit is designed;

(1)

IEC 1396/05

1₂ < 1,45 x I_z

(2)

/_z is the effective current-carrying capacity, in amperes, of the cable for continuous service according to Table 6 for the particular installation conditions:

• temperature, derating of l_z see Table D.1;

• grouping, derating of l_z see Table D.2;

• multicore cables, derating of l_z see Table D.3.

I_n is the nominal current of the protective device;

NOTE 1 For adjustable protective devices, the nominal current I„ is the current setting selected.

I₂ is the minimum current ensuring effective operation of the protective device within a specified time (for example 1 h for protective devices up to 63 A).

The current 1₂ ensuring effective operation of the protective device is given in the product standard or may be provided by the manufacturer.

NOTE 2 For motor circuit conductors, overload protection for conductor(s) can be provided by the overload protection for the motor(s) whereas the short-circuit protection is provided by short-circuit protective devices.

Where a device that provides both overload and short-circuit protection is used in accordance with this Clause for conductor overload protection, it does not ensure complete protection in all cases (for example overload with currents less than 1₂), nor will it necessarily result in an economical solution. Therefore, such a device can be unsuitable where overloads with currents less than I₂ are likely to occur.

D.3 Overcurrent protection of conductors

All conductors are required to be protected against overcurrent (see 7.2) by protective devices inserted in all live conductors so that any short circuit current flowing in the cable is interrupted before the conductor has reached the maximum allowable temperature.

NOTE For neutral conductors, see 7.2.3, second paragraph.

Table D.5 - Maximum allowable conductor temperatures under normal
and short-circuit conditions

In practice, the requirements of 7.2 are fulfilled when the protective device at a current I causes the interruption of the circuit within a time that in no case exceeds the time t where t < 5 sec.

The value of the time t in seconds shall be calculated using the following formula:

t = (k x S/Г)²

where:

S is the cross-sectional area in square millimetres;

/ is the effective short-circuit current in amperes expressed for a.c. as the r.m.s. value;

к is the factor shown for copper conductors when insulated with the following material:

EPR 143

The use of fuses with characteristics gG or gM (see IEC 60269-1) and circuit-breakers with characteristics В and C in accordance with the IEC 60898 series, ensures that the temperature limits in Table D.5 will not be exceeded, provided that the nominal current /_n is chosen in accordance with Table 6 where /_n < 7_Z.Annex Е
(informative)

Explanation of emergency operation functions

NOTE These concepts are included here to give the reader an understanding of these terms even though in this part of IEC 60204 only two of them are used.

Emergency operation

Emergency operation includes separately or in combination:

• emergency stop;

• emergency start;

• emergency switching off;

• emergency switching on.

Emergency stop

An emergency operation intended to stop a process or a movement that has become hazardous.

Emergency start

An emergency operation intended to start a process or a movement to remove or to avoid a hazardous situation.

Emergency switching off

An emergency operation intended to switch off the supply of electrical energy to all or a part of an installation where a risk of electric shock or another risk of electrical origin is involved.

Emergency switching on

An emergency operation intended to switch on the supply of electrical energy to a part of an installation that is intended to be used for emergency situations.Annex F
(informative)

Guide for the use of this part of IEC 60204

F.1 General

This part of IEC 60204 gives a large number of general requirements that may or may not be applicable to the electrical equipment of a particular machine. A simple reference without any qualification to the complete standard IEC 60204-1 is therefore not sufficient. Choices need to be made to cover all requirements of this part of IEC 60204. A technical committee preparing a product family or a dedicated product standard (type C in CEN), and the supplier of a machine for which no product family or dedicated product standard exists, should use this part of IEC 60204:

1. by reference; and

2. by selection of the most appropriate option(s) from the requirements given in the relevant Clauses; and

3. by modification of certain Clauses, as necessary, where the particular requirements for the equipment of the machine are adequately covered by other relevant standards,

providing the options selected and the modifications made do not adversely affect the level of protection required for that machine according to the risk assessment.

When applying the three principles a), b) and c) listed above, it is recommended that:

- reference be made to the relevant Clauses and Subclauses of this standard:

1. that are complied with, indicating where relevant the applicable option;

2. that have been modified or extended for the specific machine or equipment requirements; and

• reference be made directly to the relevant standard, for those requirements for the electrical equipment that are adequately covered by that standard.

In all cases, expertise is essential to be able to:

• perform the necessary risk assessment of the machine;

• read and understand all of the requirements of this part of IEC 60204;

• choose the applicable requirements from this part of IEC 60204 where alternatives are given;

• identify alternative or additional particular requirements that differ from or are not included in the requirements of this part of IEC 60204, and that are determined by the machine and its use; and

• specify precisely those particular requirements.

Figure 1 of this part of IEC 60204 is a block diagram of a typical machine and can be used as the starting point of this task. It indicates the Clauses and Subclauses dealing with particular requirements/equipment. However, this part of IEC 60204 is a complex document and Table F.1 can help identify the application options for a particular machine and gives reference to other relevant standards.

Table F.1 - Application options

Annex G
(informative)

Comparison of typical conductor cross-sectional areas

Table G.1 provides a comparison of the conductor cross-sectional areas of the American Wire Gauge (AWG) with square millimetres, square inches, and circular mils.

Table G.1 - Comparison of conductor sizes