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Type tested switchgear and its significance.
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| 6 Oct 2011 |
Dependability of power distribution system is the key to avoid interruption in power and most important - to ensure basic safety itself. This is even more important in severe operating conditions like UAE where heat, dust and humidity are prevalent.
This increases the responsibility of the designers and manufacturers of such system in delivering products which are totally reliable and safe to work on, system not only with the right protection devices but coordinated together to perform to the highest level of safety.
The quality and reliability of the switchboards can be verified to a large extent by means of type tests. Testing as a means of proving product reliability is of prime importance worldwide.
Conventional wisdom may lead us to accept a switchboard with reliable and tested components. Surely many tests are carried out on the components - the ACBs, MCCB, Contactors & ELCBS. These components are tested as per applicable IEC standards and thesetests are essential but not entirely sufficient.
This is mainly since in a practical situation abnormalities such as short circuits or other similar faults will be experienced however the switchboard still has to continue to perform satisfactorily with respect to electrical & mechanical operations.
Thus the ACB may have cleared a fault of 50KA, but this fault has been experienced also by the busbar system, possibly by other breakers too. Individually these components can clear/withstand faults but is the system ready to be put in action after a fault, and what is the extend of impact?
This brings us to a system/ switchboard which has been type tested to ensure reliability and safety. The standards to which LV panels should be manufactured is IEC 61439 standards. IEC 61439 is the International Electrotechnical Commission standard which covers low voltage switchgear and controlgear assemblies. It is a replacement for IEC60439.
This standard is a significant change from the previous one, one of the most surprising changes for some will be the removal of the terms ‘type tested assembly’ and ‘partially type tested assembly’.
A design in conformance to IEC 61439 ensures the following:
- Satisfactory performance in normal and abnormal conditions.
- Compliance with the safety requirements stipulated in the standards.
- All the switchgear, power contact assemblies, connecting links etc. are capable of withstanding / clearing the fault.
However, any switchboard may not be able to fulfill these requirements unless it is designed and manufactured to meet these requirements. Switchboards, a link between the source upstream and the load downstream, should offer the highest levels of safety, reliability and ultimately performance.
Another important element is design verification and workmanship. A dedicated team of technicians working in a systematic manner with proper quality check only can utilize fully the ‘Tested Assembly’ design and deliver quality panels.
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