There is a wide variety of test equipment on the market but does it all conform to the latest standards.
Have you recently invested in new test kit or are you thinking about it and narrowing down the choices that are available before taking the plunge? If so, are you aware of the introduction of a new British standard which came into effect on 15 July 1999. This is on top of the safety requirements of standards such as IEC 1010 and EMC requirements which also need considering when purchasing test equipment.

One range of test equipment that meets the requirements of BS EN 61557 is the Telaris from Di-log. Ash Mohammed, managing director of Di-Log, emphasises how it is increasingly difficult to select instruments that meet the requirements as laid down in the regulations while also trying to comply with the many safety requirements and standards. So where has this new standard come from, and what does it cover? As you may be aware IEC 1010 is a safety regulation for every electrical and electronic measuring device and is a standard which applies specifically to their overvoltage category ratings. In particular it deals with creepage and clearance distances on circuit boards with the aim of providing protection to the instrument and the user in the event of an overvoltage. However this standard alone is not deemed sufficient for testing the protective measures of test equipment. In addition to this there was also the need to establish reliable and comparable test results from different manufacturers' equipment. This led to the introduction of IEC 61557 which was then adopted as an EN standard and subsequently as BS EN 61557.

The aim of the standard is a means of stipulating common principles for measuring and monitoring equipment for testing the electrical safety in systems with nominal voltages up to 1000 V ac and 1500 V dc.

BS EN 61557 comprises of eight parts which are listed below, some of the more relevant points are summarised.

  • Part 1: General requirements. This deals with the common specifications for measuring equipment including: protection against extraneous voltages, specification and safety precautions against hazardous touch voltages and specification of the maximum operating error.

  • Part 2: Insulation resistance. This specifies a dc output voltage. This should not differ by more than 10% when a capacitor of 5µF is connected in parallel with the insulation resistance to be measured. The open circuit voltage should not exceed 1·5 times the nominal output voltage, the nominal current should be at least 1 mA, the measuring current shall not exceed 15 mA peak, the maximum operating error should not exceed 30% and the equipment should not be damaged nor a user be subjected to danger when a dc or ac voltage of 120% of the highest nominal voltage is applied for 10 seconds.

  • Part 3: Loop impedance. This states that the maximum operating error should not exceed 30%, a fault voltage greater than 50 V should not arise as a consequence of the test. The equipment should not be damaged nor a user subjected to danger when it is connected to 120% of the nominal voltage.

  • Part 4: Resistance of earth connection and equipotential bonding. The measuring voltage may be an ac or dc voltage. The open circuit voltage should not exceed 24 V and should not be less than 4 V. The measuring current which has the minimum measuring range should not be less than 200 mA and the resolution for digital instruments should be at least 0.01 V.

  • Part 5: Resistance to earth.

  • Part 6: Residual current devices.

  • Part 7: Phase sequence.

  • Part 8: Insulation monitoring devices for IT systems.

    So when it comes to deciding on new test equipment make sure that as well as meeting your requirements it also meets the relevant standards.

    Fast form filling

    Doing the work is fine. You just get in there do what you’ve got to do and get out. It’s the form filling that takes the time. Wouldn’t it be good if you didn’t have to do it? OK, we know that isn’t going to happen but wouldn’t it be good if there were some easy way of completing all those certificates quickly and easily? Well there is. FastTest, from Amtech Computer Systems, is a test certificate software package designed to take the wrist ache out of form filling. FastTest contains a full range of inspection and commissioning certificates. It also has a document management/filing system to store all previously issued certificates. Amtech believes that FastTest’s ease of use is its biggest bonus. The company is marketing the product with the slogan What you see is what you get! meaning what appears on-screen is what appears on paper. The on-screen layout has blank spaces for information such as addresses, and click on icons with drop down menus to choose standard information like dates, standard numbers etc. Fill in the blank spaces and the form is complete but, if you’re not sure that all’s correct, the validate command checks that the form has been filled in satisfactorily and, if not, prompts appear where an omission or mistake has been made. FastTest is available in three versions. FastTest Basic will produce BS 7671 certificates and inspection reports and is fully endorsed by the NICEIC for printing on to its computer friendly certificates. FastTest Standard includes the full range of certificates mentioned above. It also has a range of reports and site inspection sheets, circuit charts and schematic logic diagrams. FastTest Plus includes all of the FastTest Standard features plus more – Data Extract and Merge allows installation details to be saved individually to disc and Single Cable BS 7671 is a cable sizing program which includes a database of cables and circuit protection devices. FastTest is available as a stand-alone program or as part of Amtech’s Office software package. The company is currently in dialogue with the ECA to include ECA approved documentation on the software.

    • Source

    Electrical and Mechanical Contractor