OPERATIONS & MAINTENANCE
ELECTRICAL SAFETY IN LOW VOLTAGE SWITCHGEAR
A guide to managing ambiguous specifications
E
lectrical safety in low voltage switchgear is not a new topic, since the dangers associated with the manual operation of
any electrical switchgear, particularly on-load switching, have always been present. Through personnel training and certification, all certified electrical technicians/engineers will be aware of the risks to both personal safety and operational assets during electrical switching. However, without a defined
international standard for LV products to provide arc-fault containment (IEC TR61641:2014 is still only a test report) the requirements defined by end-users or in specifications can be varied or ambiguous as the natural reaction is often to default to the most onerous possible requirement without fully understanding the options available. The result is often provision of a premium solution which may not give the end-user the best fit in terms of maintenance and/or operational safety. A good overview of Arc-Fault capability was provided back in 2017 by GAMBICA in their guide which is still available on-line for free. For new projects Blackburn Starling
& Co. Ltd are often asked to provide solutions which can include one or more of the following features:-
• LV switchboards/MCC specified to comply fully with IEC/TR61641:2014. These can be provided as a premium product to comply with arcing classes (A,B or C) as detailed within the test report. The GAMBICA guide is again recommended to select the relevant arc class for containment to provide purely personnel protection (Class A) through to containment within individual functional units or sections (Classes B or C) when related to Form 4 switchgear.
26
www.engineerlive.com
Off-Site build of a modular LV electrical switchroom
• Fully insulated busbar systems to preclude an arc-fault occurring within the low voltage panel, this is to provide compliance with section 6.1 of the test report.
• OEM products to incorporate safety features including:- Air-circuit breakers which include maintenance modes to limit the fault level of the circuits whilst an engineer is switching the ACB for maintenance. Arc-flash detection equipment where the protection relay has a fibre-optic cable installed throughout the length of the busbar chamber within an LV panel to provide a high-speed trip to the main circuit breaker upon detection of an arc- flash incident.
• The supply of remote operator panels or pendants to allow the switching of the circuit breakers to be carried out without the need to have an engineer standing in front of the panel thereby reducing the risk of any injury from arc-fault incidents.
Once installed on site the PPE
category, incident energy and safe working distance for the switchgear should also be calculated to allow this information to be displayed on each section of the LV equipment. All manufacturers should be able to assist with these calculations, Blackburn Starling & Co. Ltd use a licensed software package for this purpose with data both from our own installed equipment and details of the external field cabling, transformers etc. As with all bespoke equipment it
is always recommended to have the conversation as early as possible in the design phase of a project to allow the LV switchgear supplier to advise on their recommendations and options. Following a review of the options available, the client can choose the most appropriate method for their site and operations teams to provide the optimum solution.
For more information visit:
www.blackburn-starling.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
