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Compliance Engineering
News Release from: Clare Instruments | Subject: EN50191
Edited by the Electronicstalk Editorial
Team on 03 August 2004
EN50191 sets safety test standards
John Barnett of electrical safety testing specialist Clare Instruments provides a guide to EN50191 and the safe operation of electrical test installations.
Manufacturers of electrical and electronic products clearly understand that to protect consumers, several types of electrical safety tests must be carried out on products to ensure compliance with industry standards for construction and performance However, in instigating formal electrical safety testing procedures on the production line or in design or type testing laboratories, there is also the need to ensure that the personnel undertaking those tests remain safe from the dangers presented by working with electricity
This article was originally published on Electronicstalk on 27 Oct 2006 at 8.00am (UK)
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Although EN50191 has no reference to CE marking or any other manufacturing product standard, compliance is required to establish safe working conditions and evidence that appropriate due diligence has been adopted.
Despite the standard defining four conditions when conformance will not be required (linked to frequency of products under test along with voltage, current and, discharge levels at live exposed points), the majority of organisations involved in the manufacture of electrical or electronic products and components will need to comply.
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On production line test stations, for example, different safety requirements are highlighted depending on whether the test location has automatic protection against direct contact with live parts (such as full test enclosures) or not.
In each case EN50191 includes a mix of technical protective measures, for example on insulation levels, with physical requirements in the shape of barriers, signals and lamps.
The standard details five definitive test installations and the levels of protection required.
The first is "Test station with automatic protection against direct contact", where the use of test enclosures encapsulate the device under test and prevent any contact when the tests are applied.
The second is "Test station without automatic protection against direct contact": this could be a product that is too large to allow the use of a test enclosure and where prohibited areas will have to be used with fixed barriers to prevent access to the device under test from external personnel.
The third covers "Test laboratories and experimental stations": each test area within a laboratory will need individual protection and isolation, as a common emergency cutoff might increase the risk to another area, increasing the possible hazards at other test stations.
The fourth is a "Temporary test station", where a skilled engineer is undertaking testing on a client's site or in a single situation on a special designed device: individual assessment of the area and exclusion zones will have to be implemented to meet the specific location and situation.
The fifth and final category is "Test station without test personnel in permanent attendance": in situations where automated production lines or life testing is undertaken, full protection with automatic cutoff must be used in every position of entry to the device under test.
The standard includes a series of fundamental measures for all test locations.
These include emergency switching-off procedures, preventing automatic energising, protection against residual voltages and other specific requirements.
In addition there are further measures for different test environments, which vary with the level of risk associated with it.
Depending on the sort of test station being used, there are specific instructions on the size of test areas, the use of prohibited zones and protective barriers to be fitted, including indicator lights and appropriate signage.
Apart from the test installations themselves, EN50191 also provides guidance on the competence of the personnel performing the tests and those who are in control of the testing operations.
EN50191 aims to establish a consistent level of safety throughout Europe for all electrical testing installations.
Clearly test instrument manufacturers will need to offer solutions for the safe use of their instruments and the end user will have to satisfy the need for designated test areas and skilled and trained operators.
In summary, EN50191 will have an impact on all companies carrying out electrical safety testing on electrical equipment and particularly on those individuals and organisations that have a duty under the Health and Safety at Work Act.
Clare Instruments has published a free practical guide to EN50191. Request a free brochure from Clare Instruments ...
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