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ELECTRICAL SAFETY
However, where there is no such dedicated standard, EN 60204-1 requires that it must always include:
verification that the electrical equipment complies with its technical documentation
in case of protection against indirect contact by automatic disconnection, conditions for protection by automatic disconnection shall be verified according to 18.2
functional tests
EN 60204 often requires only a self- declaration against the conformance process. However, this does depend on the type of machine. For example, if EN 60204 was used for the presumption of conformity of an Annex IV machine, the electrical parts would still be included in the “special procedures” required. The complexity of EN 60204, coupled with the potential lethal consequences if electrical safety is incorrectly administered, means that compliance is not a process that machine users can afford to get wrong. However, the development of a practical checklist is a useful approach that will help ensure all relevant considerations have been covered.
OTHER REQUIREMENTS
equipment (Clause 5.5) instead of simply “devices for disconnecting…”. This is because while there has always been a distinction between “isolation” and “disconnection”, it has not always been easily understood. This addition therefore helps with clarification. Isolation is a “procedure to securely disconnect and separate a machine from all hazardous energy sources” (source BS 14100). Measures for protection against electric shock are also described. The measures are for protection against direct contact (basic protection), and for protection against indirect contact (fault protection). This is followed in the standard by measures for the protection of equipment. Equipotential bonding
(earthing/grounding) is a basic provision for fault protection, so the standard also describes detailed requirements for protective conductors. Control functions are the subject of clause 9 of the standard. Basic functions are included but there are also additional functions described. For example, clause 9.3.6 considers the “suspension of safety functions and/or protective measures” with specific requirements for mode selection to deliver clarification and emphasis. This is important because selection of a different operating mode may have an impact on the risk. For example, when a guard interlock is bypassed to allow operation for maintenance or setting purposes. Clause 10 of the standard includes colour coding and marking requirements for actuators. Also, unless otherwise agreed
between the machine supplier and the user (the details of which is covered in Annex B of EN 60204-1), machine status indicator lights should be colour coded, with each colour identifying a specific status.
An example of the use of specific colours in Section 10.2 “Actuators” is reserving the red/yellow colour combination for “emergency operation devices”. It also reserves the colour yellow “…for use in abnormal conditions, for example, in the event of an abnormal condition of the process, or to interrupt an automatic cycle.”
IS YOUR MACHINERY COMPLIANT? Clause 17 of the standard outlines what technical documentation is required to demonstrate compliance. This includes information relating to a machine’s electrical installation, operation, and maintenance, which can be in the form of drawings, diagrams, charts, tables, and instructions. While verification can be done at different stages throughout the design and development lifecycle process, even at the end of it, it would be better to do this as early as possible during design. As verification is intended to assure the conformity of a product, it is more cost-effective for faults to be identified and rectified during design, rather than waiting until the final machine is produced.
The extent of the verification that is required is made clear in the specific product standard that relates to each different type of machine.
Alongside the specifics of EN 60204, there are several global directives for electrical equipment and components with which machinery must comply. The Low Voltage Directive (LVD) (2014/35/EU) ensures that electrical equipment falling within specific voltage ranges provides a high level of protection for European citizens and takes full advantage of the single market. The Machinery Directive consists of a comprehensive set of health and safety regulations that machinery manufacturers must declare they have complied with to sell their products in the EU. For the UK market, the Supply of Machinery (Safety) Regulations 2008 continues to be in alignment with the EU’s Machinery Directive. These are closely linked and require compliance with the LVD (The Electrical Equipment (Safety) Regulations 2016 in the UK) and the ATEX Directive (UKEX in the UK). The latter of these regulates the requirements for equipment that is used in potentially explosive atmospheres. Alongside these, the EMC Directive (Electromagnetic Compatibility Regulations 2016 in the UK) aims to control electrical interference between different devices, and compliance with it is mandatory. This means that all electrical equipment and machinery must be explicitly tested, certified or marked. With so many electrical components, it is vital to test electrical safety and ensure compliance with the complex array of relevant standards and regulations.
TÜV SÜD
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