Distribution networks are probably the largest and most complex systems to maintain but do have an excellent record for safety and reliability. Protecting transformer equipment by means of fused ring main units on cable networks has been used for many years and whereas engineers could argue that these are tried and tested solutions, new or improved current limiting devices are now being investigated.
High performance back-up current limiting fuses fitted in to ring main units could be difficult to replace with alternative devices; advances in fuse technology should ensure that the familiar fuse-link will be the product of choice for some years. Medium voltage current-limiting fuse-links are the principle protection device used by electrical utilities and switchgear manufacturers worldwide. The fuse-link is safe, reliable, environmentally friendly and cost effective but is mostly specified for speed of operation and current limiting ability in the event of a short circuit fault. The speed of operation reduces the effects of short circuit currents limiting the energy delivered to the circuit fault, preventing what could be catastrophic results caused through high faults and disturbing voltage arcs.
Cooper Bussmann has launched the T Range Medium Voltage current limiting fuse-link to the dimensional standard DIN 43625. Developed by engineers based at the Cooper Bussmann UK medium voltage product development centre, the range complies with the latest issue of IEC 60282-1, they are lead and cadmium free (Complying with RoHS and WEE directives) and are designed to meet both current and future electrical utility specifications worldwide.
Cooper Bussmann along with other leading manufacturers operates a recycling scheme for all medium voltage fuse-links. The fuse-links are suitable for both indoor and outdoor applications and are fitted with a spring striker. The T range offers time current characteristics that are optimised to improve discrimination with upstream devices, ensuring fast clearance of earth faults in secondary terminal zones. The fuse-links utilise the Cooper Bussmann M effect technology, ensuring low power consumption during operation, whilst at the same time providing temperature limitation in the event of an overload fault. Medium voltage fuse-links of a given rating could run 10-30° cooler than comparable fuse-links which do not employ M effect. This advantage is particularly useful when the medium voltage fuse-link is installed in a totally enclosed unit employing insulated equipment, such as cast resin fuse switches or compact insulated ring main units. When the T range fuse-link operates under low fault conditions, the maximum temperature rise of the fuse-link ensures that the temperature limits for insulated fuse switchgear are not exceeding 160°C, therefore the fuse-link barrel remains intact and the fuse carrier and its contacts remain unimpaired.
The Cooper Bussmann medium voltage range of fuse-links have been fully tested and certified. The interrupting performance has been achieved and certified at the leading independent test laboratories of KEMA. All other required performance requirements such as temperature rise, time current characteristics and weather sealing etc. have been rigorously tested to the ASTA approvals procedures. Cooper Bussmann is the pioneer in the development of Full Range Medium Voltage fuse-link technology manufacturing innovative, high quality products with ISO 9002 ‘approved systems'. The engineering team is in the forefront of international standardisation of medium voltage fuse-links and offers a comprehensive service of advice on selection and applications. With over fifty years experience in design and manufacture, Cooper Bussmann has supplied fuses to over ninety countries worldwide.
Innovative designs and quality of product testing and manufacture ensures reliability in service. Medium voltage fuse-links are constructed by welding or brazing of the joints, ensuring a very mechanically robust finish. Each fuse-link is X-Rayed to ensure element alignment, thus overcoming defects that could not normally be detected by purely visual or electrical based quality systems. Additionally as a 24kV DIN fuse-link can be used on a 12kV system, utilities that run a mixed voltage network can standardise on one type of switchgear with one type of fuse-link, reducing costs and removing the need for an additional fuse extension and excessive inventory. The T range covers all DIN requirements within the ranges from 3.6kV to 36kV and the fuse-links are complimented with a range of 12/24kV Medium Voltage DIN Fuse-Bases.
Fuse technology has advanced in recent years and we need to be reviewing distribution systems which will ensure even safer and more reliable service. Commercial and environmental forces will ensure that equipment will cost less to build and install but will incorporate products which are safe, reliable and environmentally friendly. Fuse-link technology will have an important role to play in both the latest and future designs of equipment specified for distribution networks.
A catalogue detailing the medium voltage fuses is available from the sales department: [email protected]. Please quote reference "MVDIN-2008"
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