Switchgear & substations - Model railway project

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Bernard Johnson, programme controller for the ABB Mowlem Southern Region Power Supply Upgrade (SRPU) team, explains how detailed planning, coordination, collabora-tive working and an uncompromising approach to health and safety helped make the project so successful that in the end nobody noticed it!

In 2003, Network Rail embarked on its three-year Southern Region Power Upgrade (SRPU) programme to support the introduction of 2000 new, more comfortable carriages. Thanks to features such as central door locking, CCTV and air conditioning, the Bombardier Class 375/376 Electrostar and Siemens Class 450 Desiros trains draw around 23 per cent more power than the old rolling stock from the 750V traction power supply system – the reason for the upgrade.
With 3,196 miles of track, Southern Region is the UK’s largest private operator of an electrical distribution system. And the upgrade is believed to be the largest DC project of its type undertaken anywhere in the world.
Kent region
ABB in consortium with Mowlem Railways was one of four regional contractors appointed initially by Network Rail, and the consortium was awarded the Kent region – extending from Ramsgate on the coast through to Cannon Street substation in central London. Between 2003 and 2006 the consortium carried out around £80 million of project work including the construction or upgrading of 27 substations and 17 feeders and installing around 100 panels of ABB ZX1.2 gas insulated MV switchgear and 25km of 33kV cable.
Working on one of the world’s busiest rail networks presented a whole raft of challenges and constraints as all site deliveries, possessions and outages had to be planned down to the finest detail. This was especially important because, while the SRPU project was vital for Network Rail’s future plans, its over-riding need was of course to keep the trains running on a day to day basis, so potential disruption and delays had to be kept to an absolute minimum.
It was clear that communication and coordination at all stages, from definition, through design, tender for the individual work packages to execution, would be the key to the success of this project. So it was decided to take the unusual step of co-locating the consortium team alongside the client team in Network Rail’s project office in central London. This ensured that right from there start there was no ‘us and them’, but rather a partnership that enabled problems to be solved before they became issues.
Possessions
Management of ‘possessions’ – the windows of opportunity when access was available to work on individual sites – was a core element handled by specific team members. This was particularly challenging as six months is a normal period of notice for a possession, while on some of the busiest routes access was only available at Christmas, so they had to be planned 12 months ahead. Added to this, Network Rail’s operational requirements sometimes meant that planned possessions had to be cancelled at the last moment, calling for the team to think on its feet to reorganize work programmes to maintain the overall project momentum.
Much of the site work was carried out at night and weekends. The team also became particularly adept at ‘piggybacking’ on access to sites that had already been granted to Network Rail’s own team for routine track maintenance. Of course, with two different teams on site working with different objectives, careful planning was needed to ensure there was no clash of priorities.
Deliveries
Hand in hand with the planning of possessions, the delivery of equipment to the sites was planned with military precision. A great deal of effort went into making this a ‘non-rail’ project where possible, using road access rather than rail to deliver equipment, although there were a number of ‘rail-locked’ sites with no road access. On some sites, the limited access called for specialized rail-mounted cranes to manoeuvre heavy equipment into position. Again this required long-term planning as there are only three such cranes in the UK.
In order to keep on-site work and costs down, the project made substantial use of containerized substations, which were fitted out off site. They are housed in robust, long-lasting, stainless steel enclosures that should last for 40 years.
Health and safety
An uncompromising approach to creating a safe working environment was paramount throughout the project, with the emphasis on minimizing potential risk to site operatives. This was reflected in a remarkable safety record. All work on the infrastructure was undertaken with the Rimini plan system, which is used to make sure the safest system of work is used when ‘on the line’. In addition a safety coach was kitted out, known affectionately as ‘Thunderbird 3’. This was despatched to the various sites to show videos and provide information and handouts about the specific safety issues that the working gangs might encounter on that site.
Innovative team approach
Mid-way through the project a substantial work package was started for the north Kent ring of substations. Because of the way the substations in the ring are linked together it was not possible to take two out of service at the same time without disrupting the network. So an innovative approach was adopted by constituting a separate, dedicated planning team with representatives from all interested parties. The team was led by Network Rail, and as well as the consortium it also included the Scada team, the network controller, the outage planner and representatives from the team working on the inner London region of the SRPU, since our work could also impinge on their area. By meeting on a weekly basis the 12-strong planning team ensured that the north Kent ring work package proceeded without a hitch.
ZX1.2 switchgear
For the SRPU project ABB used its ZX1.2 range of metal-clad gas-insulated medium voltage switchgear which has technical acceptance from ENA (the Energy Networks Association) and Network Rail for use at 33kV for ratings up to 31.5kA and 2000A.
ABB designed the ZX1.2 with a modular, plug in approach to meet the specific needs of electricity distribution network owners and operators by providing compact, flexible substation configurations that offer reliable and cost efficient switchgear solutions for single busbar applications. Key design features include laser welded stainless steel enclosures, compact modular construction and the introduction of plug-in technology which facilitates simple, controlled connections of busbar, cable, test bushings and voltage transformer, without the need for ‘on site’ gas handling equipment.
All maintenance-free live components, such as switching devices and busbars, are contained under SF6 in gas-tight enclosures, which eliminate the effects of ageing processes and environmental influences to ensure maximum operator availability and a long service life. The ZX1.2 design also offers easy cable access at the rear with generous provision for conventional control and protection devices, dedicated cable test sockets and full mechanical interlocking between the disconnector/earthing selector and the circuit breaker
Underneath the arches
The innovative side of the consortium really came to the fore in constructing a new substation in Vauxhall. Space is at a premium in this part of London and it was difficult to see where it could be placed. The consortium hit on the idea of utilising two dilapidated arches of a railway bridge to create a smart new indoor substation. As well as special cladding to make the substation watertight, ventilation and fire detection systems were installed to ensure the complete safety of the enclosed transformer.
People
The success of the SRPU project was not just down to procedures. A key aspect was the excellent people working as a team across the board - civils, engineering, project management and installation and commissioning staff, supported along the way by administration and specialist safety and possession staff.
At the peak in January 2005, there were around 140 ABB Mowlem project staff, along with many other installation, civils, cable pulling contractors and site staff.
The final verdict
By November 2005 all the new trains were in service, with not one train introduction delayed due to a lack of power, and Network Rail’s view on the overall Southern Region Power Upgrade project was – “the project so successful that in the end nobody noticed it!”