Group Safety Standards IEC60204-1: 2016 | USA

ISO 12100 describes that IEC 60204-1 “Safety of machinery - Electrical equipment of machines - Part 1: General requirements” should be referred to for measures against electrical hazard sources based on results of risk assessments. IEC 60204-1 is an important standard in the area of machine safety that forms the basis to ensure the safety of electrical equipment.

There are three purposes of this standard as follows:
•    Safety of persons and property (including equipment, devices, components, etc)
•    Consistency of control response
•    Ease of operation and maintenance

Its purpose includes not only to prevent persons from getting an “electric shock”, but also to prevent a machine itself, devices to be used, and components of work piece from being damaged due to an “electrical fire” and the like. In addition, the standard is also aimed at ensuring “response to control as intended”, “operability based on the ergonomic principles”, and “ease of maintenance”. The requirements to achieve these goals are described.


The scope of the standard is as follows.
•    Electrical, electronic and programmable electronic equipment and systems used for machines not portable by hand while working (including a group of machines working together in a coordinated manner)
•    Inside of the electrical equipment of the machine from the connection point of the electrical supply
Electrical equipment that operates with nominal supply frequencies not exceeding1000 V AC/1500 V DC and with nominal supply frequencies not exceeding 200 Hz


This standard does not specify additional and special requirements that can apply to the electrical equipment of machines that, for example:
•    Machines to be used in open air (outside of buildings or other protective structures)
•    Machines that use, process, or produce potentially explosive material (paint, sawdust, and so on)
•    Machines intended for use in potentially explosive and/or flammable atmosphere
•    Machines at special risk when a certain material is used or produced
•    Machines intended for use in mines
•    Sewing Machines, units, and systems (specified in IEC 60204-31)
•    Hoisting machines (cranes, hoists, and the like, specified in IEC 60204-32)
•    Semiconductor fabrication equipment (specified in IEC 60204-33)

Figure 1 shows the sections relevant to this standard.

First, electric parts and electric equipment to be used shall satisfy the following.
•    Suitable for the intended usage
•    Conform to the relevant IEC standards, if applicable
•    Used in accordance with the supplier’s instructions

In addition to satisfying the above, the electrical equipment shall be correctly operated under the following conditions.

Voltage range (4.3)

Transportation and storage (4.5)

To connect the input  supply conductor with the electrical equipment of the machine, such as a control panel, the supply conductors are terminated at the supply disconnecting device  or a plug (socket outlet) is used. At that time, it is recommended that the machine is connected to a single incoming supply.

Requirements for supply disconnecting devices (IEC 60947-3 is one of applicable standard)

It is necessary to install a supply disconnecting device for each  incoming supply for the machine and each  on-board power supply mounted on the machine. （5.3.1）
Supply disconnecting devices serve to disconnect the electrical supply of the factory from the inside of the control panel, for example, when maintenance person open the control panel and perform some kind of maintenance. By this measure, the maintenance personnel can perform the maintenance without being exposed to electrical hazard sources. Since the supply disconnecting devices have such an important role, they shall satisfy all of the following requirements.

•    The positions of OFF (disconnected) and ON (closed) shall be marked with symbols “○” and “｜”, respectively.
•    Gap between the contacts can be visually observed. Alternatively, the device has a position indicator that cannot display OFF (disconnected) until the supply conductor is disconnected.
•    The device has a  operating means  (for example, a handle)  external to the enclosure. If it is not intended for emergency operations, black or gray is recommended for the color of the handle. If it is intended for emergency operations, the color of the handle shall be red with yellow background.
•    The device is equipped with a measure (for example, a padlock) to lock the position at OFF (disconnected).
•    All charging conductors of the power supply circuit can be disconnected.
•    The breaking capacity of the device have sufficient to interrupt the current of the largest motor when stalled together with the sum of the normal running currents of all other motors and other loads. 
 

•    The operating mean of a supply disconnecting device shall be provided at an easily accessible location between 0.6 m and 1.9 m above the  servicing level. The recommended maximum height is 1.7 m.


Excepted circuit:

An excepted circuit is a circuit that may not be disconnected with a supply disconnecting device for securing safety in the event of problem or during maintenance. The following can be considered to be an excepted circuit.

▶  Power supply circuit for lighting required for maintenance or repair
▶ Socket outlet for the exclusive connection of repair or maintenance tools and equipment (for example hand drills, test equipment) 
▶ Under-voltage protection circuit that are only provided for automatic tripping in the event of supply failure
▶ Circuit supplying equipment that should normally remain energized for correct operation (for example temperature controlled measuring devices, heaters, program storage devices). 
 

However, it is recommended that such circuits be provided with their own disconnecting device. 
 

Electrical facilities  shall provide measures of protection against an electric shock due to contact of a human body or a body part with a live part of electrical equipment.
In IEC 60204-1, a live part is defined as “conductor or conductive part intended to be energized in normal use, including a neutral conductor, but, by convention, not a PEN conductor (3.1.38)”.
There are two types of electric shocks and they are defined as follows.

•    Direct contact (3.1.15): contact of persons or livestock with live parts 
Indirect contact (3.1.34): contact of persons or livestock with exposed conductive parts (Note 1) which have become live under fault conditions  
Note 1: Conductive part of electrical equipment, which can be touched and which is not live under normal operating conditions, but which can become live under fault conditions 
 

In the protection using a PELV, measures are taken to protect a person from an electric shock due to indirect contact or direct contact with a limited direct contact area.
 

Refers to measures of preventing breakdown of the equipment and electrical fire due to overcurrent or temperature rise. Typical measures include protection of equipment by using an overcurrent protective device.

If the circuit current in the electrical equipment could exceed either of the rated value of a component or the allowable current of the conductor, whichever is smaller, an overcurrent protective device shall be used (7.2.1).

An equipotential bonding is “provision of electric connections between conductive parts, intended to achieve equipotentiality  (3.1.26)”, including the protective and functional bonding.

The protective bonding is “ equipotential bonding for protection against electric shock (3.1.49)”, while the functional bonding is “equipotential bonding necessary for proper functioning of electrical equipment (3.1.32)”.
As it is described in the  standard that “Protective bonding is a basic provision for fault protection to enable protection of persons against electric shock”, the protection bonding plays an important role especially when an insulation failure occurs.

A protective bonding circuit is configured with interconnection of the following. （8.2.1）
● PE terminal (terminal for connecting the external protective conductor)
● Protective conductor inside the  equipment of machine (note)
Note: A conductor that serves as the primary fault current path from the exposed conductive part to the protective earth (PE) terminal of the electrical equipment.
● The conductive structure part and the exposed conductive part of the electrical equipment
● The conductive structure part of the machine

By interconnecting these, protect a person from electric shock due to a ground fault and earth leakage in the event of an insulation failure.

Note that, if an earth fault  occurs, a large current may pass through the protective conductor. Therefore, the protective conductor shall be able to withstand thermal stress due to a large current. In addition, it is also necessary to prevent mechanical damage to the protective conductor in order to secure the conductivity of the protective bonding circuit.
 

The contacts of the protective conductors require one of the following labels or indications.

•    Symbol：
•    Letters “PE” (the graphic symbol is preferred)
•    Combination of two colors: green and yellow
•    Combination of the above

Note that, for the connection points of the functional bonding, it is recommended to mark the symbol：

As described in the purposes of IEC 60204-1, it is important for safety to secure the consistency of control response. Accordingly, the following requirements exist.
•    Supply voltage of the control circuit
•    Stop and operation as the control functions

If the control circuit is supplied with AC, a transformer shall be used for the control circuit.
This transformer shall  have a separate windings . （9.1.1）
In addition, the control circuit voltage should not exceed the following values. （9.1.2）

AC control circuit
- Nominal frequency 50 Hz, 230 V
- Nominal frequency 60 Hz, 277 V

DC control circuit
- Nominal voltage 220 V

As mentioned in “5. Protection of equipment”, the control circuit shall be provided with an overcurrent protective device. （9.1.3)

Start functions (9.2.3.2)

The start functions of the machine shall be operated by energizing the machine. The machine shall be able to be started only when the safety functions and/or the protective measures are in place and are operational.

Stop functions (9.2.3.3)

The stop functions shall override related start functions. The stop functions are classified into the three stop categories as follows. It is necessary to select one of the stop categories according to the risk assessment and/or the functional requirements of the machine.

The control device of the operator interface shall minimize the possibility of human errors (failed operation due to carelessness) with the arrangement of the equipment, appropriate design, and complementary protective measures. To this end, the ergonomic principles shall be considered.

Colors of actuators

The actuators such as push button switches shall be color coded according to the table below. 

Colors of indicater lights 

Location and mounting  (11.2)

Required specifications of enclosures (11.3, 11.4)

•    If the enclosure is provided with an opening (for example, a cable port), measures shall be provided to secure the required protection level of the equipment.
•    The opening for leading in cables shall be easily opened on site.
•    An appropriate opening may be provided at the bottom of the enclosure in the machine in order to drain dew condensation.

Conductor of cables

Insulation of cables

•    Withstand voltage required for insulation  of cables and conductors (12.3)
- If 50 V AC or 120 V DC is exceeded, testing voltage of 2000 V AC for a duration of 5 minutes
- For PELV circuits, testing voltage of 500 V AC for a duration of 5 minutes

•    The mechanical strength and thickness of insulation  shall  prevent the insulation from being impaired during operation or installation (12.3)

•    For the insulation, it is necessary to consider hazard sources due to flame propagation properties and occurrence of toxic or corrosive haze (12.3)
 

Current-carrying capacity of cables

Cable voltage drop

Requirements for wiring

•    Fix the conductors in the enclosure as necessary
•    For a nonmetallic duct, use a flame retardant insulation material.
•    The wiring of the electrical equipment mounted in the enclosure should be modified from the front. If a control device is connected on the back side of the enclosure, a door or outward opening panel shall be provided.
•    A flexible conductor shall be used for connections to the parts mounted on a door or moving part.
•    The conductors and cables that are not accommodated in ducts shall be appropriately fixed .
•    The wiring for control circuit to the outside of the enclosure shall be connected via a terminal box or a plug and socket combinations .

Colour coding 

The conductors  shall be identifiable using indications or colors.
Colors that can be used: black, brown, red, orange, yellow, green, blue (including light blue), purple, gray, white, pink, and turquoise (blue green)

Table 6: Wiring colors (recommended)

For power supply	Colour-coding(IEC 60204-1:2005)
AC power circuit	Black (light blue is recommended for neutral conductor)
DC power circuits	Black
Protective conductor	Combination of green and yellow
AC control circuits	Red
DC control circuits	Blue
Excepted circuits	Orange

Protective conductor: a combination of green and yellow (one color covers 30% or more and 70% or less) shall not be used for the wiring other than protective conductors/protective bonding conductors.
Cases where the wiring colors above may not be observed
•    Individual devices that are purchased with their internal wiring completed. When no insulator with the specified color is available.
•    When a multi core cable is used with colors other than the combination of “yellow and green”.

For enclosures with built-in electrical equipment at risk of causing electric shock, the graphic symbol on the right shall be displayed.

It is necessary to consider the risk of a hot surface due to the components of electrical equipment that generate heat. The temperature of parts which a person could come in contact shall not exceed the limiting value required in ISO 13732-1.
For the parts where the limiting value may be exceeded, protective measures against unintended contact shall be provided or the graphic symbol on the right shall be displayed.

Information required for nameplates used in the facility
•    name or trade mark of supplier 
•    certification mark or other marking that can be required by local or regional legislation, when required. .
•    type designation or model, where applicable 
•    serial number where applicable 
•    main document number (see IEC 62023) where applicable 
•    rated voltage, number of phases and frequency (if AC), and full-load current for each incoming supply  

The following shall be supplied  as technical documentation
a) where more than one document is provided, a main document for the electrical equipment as a whole, listing the complementary documents associated with the electrical equipment.  

b) Identification of electrical equipment (refer to 16.4)

c) Including the following, information on installation and mounting
•    Description of installation and mounting of electrical equipment and connection to an electrical supply (if applicable, other electrical supplies)
•    Short circuit current rating of electrical equipment of each electrical supply
•    Voltage rating, number of phases and frequency (for AC), type of earthed system (TT, TN, IT), and full load current of each input electrical supply
•    Additional conditions of electrical supply related for each input electrical supply (for example, maximum supply impedance, leakage current)
•    Space required for removal or service of electrical equipment
•    Requirements for installation, if it is necessary to ensure that arrangement for cooling is not impaired
•    Environmental restrictions (for example, lighting, vibration, EMC environment, and airborne contaminants), as necessary
•    Functional restrictions (for example, start peak current and allowable voltage drop), as necessary
•    Precautionary measures related to electromagnetic compatibility required for installation of electrical equipment

d) an instruction for the connection of simultaneously accessible extraneous-conductiveparts in the vicinity of the machine (for example, within 2,5 metres) such as the following to the protective bonding circuit 
•    Metallic pipe 
•    Fence
•    Ladder
•    Handrail

e) Information on the functions and operations including the following (as necessary)
Overview of the structure of electrical equipment (for example by structure diagram or overview diagram))
•    Procedure of programming or configuration required for intended usage
•    Procedure of restart after an unexpected stop
•    Operation sequence

f) Information on maintenance of electrical equipment including the following (as necessary)
•    Frequency and method of function testing
•    Instruction on the procedure to safely perform maintenance, and the procedure to interrupt the safety functions and/or protective measures (refer to 9.3.6)
•    Guide for frequencies and methods of adjustment, repair and preventive maintenance
•    Details of interconnection of electrical devices for replacement (for example, with a circuit diagram and/or connection table)
•    Information on required special devices or tools
•    Information on spare parts
•    Information on possible residual risks, description of necessity of special trainings, and specifications of personal protective equipment if necessary
•    Explanation of restriction limiting use of the keys or tools to only electricians and electrical workers, when applicable
•    Settings (dip switches, programmable parameter values, etc.)