Christmas lights! An electrical update for the new P2.

With the system design largely complete the Electrical System Specification has been updated to reflect all the new design elements.  A start has been made on writing the section on standards compliance, which involves a clause-by-clause assessment of relevant standards.  Many standards have been replaced since we designed the A1 so this represents a lot of new work.  We are also using the electrical system to pilot the Trust’s updated approach to risk assessment.  This is based on the new railway Common Safety Method for Risk Evaluation and Assessment (CSM-RA).  A first draft Hazard Log has been produced.  This describes potential safety hazards associated with the electrical system and lists causes, consequences and safety measures for each hazard.  A Risk Ranking is then allocated to each one and, where appropriate, additional mitigations are put in place.  The updated draft documents are currently under review by Graham Nicholas, the Trust’s Professional Head of Engineering.

Some of the structured electrical trunking and junction boxes. – Daniela Filová

Starting the turbogen on the A1 involves a manual process of warming through the turbine to expel water before running it up off-line and connecting the power supplies once it is operating at full speed.  DB Meiningen offers a control box which contains a circuit that uses the alternator tachometer output to determine when the turbine is up to speed before automatically connecting it to the batteries using relays.  However, this system is designed for direct battery connection.  The A1 system connects the turbogen via DC-DC converters, which is incompatible with the Meiningen circuit, so we have not used it on our engine.

As we are moving to a two turbogen solution for the P2 we are taking the opportunity to design our own start-up circuit, so the crew do not need to manually start and bring each turbogen online.  A prototype tachometer circuit has been designed and bench tested.  This will be used to drive a relay which will connect the turbogen to the loads once it is running above a pre-determined speed.  The next step will be to test this on the A1 when it is next in steam to confirm the optimum speed for switching.  The circuits will then be incorporated into the Turbogen Control Box system, which has already been designed.

The prototype tachometer set-up. – Rob Morland

Work on the new combined head/tail/marker lamp luminaire continues.  We have received the first driver PCBs back from Stevenage Circuits and Alan Green has built and tested an initial batch for use in finalising the design.  Roger Millington, Alan and Rob are now working together to ensure that the lamp performance when displaying each of the three aspects is optimised.

The initial delivery of driver PCBs for testing. – Rob Morland

For the rear of the tender we are planning to use two original Stones marker lamp housings to display the marker and tail aspects, as on the A1.  Provision will be made for fitting and connecting the new P2 headlamps to display the head aspect when running tender-first on the main line.  Alan Green has updated the A1 marker/tail driver circuit design to include modern driver components (the original design is now 12 years old!).  This will be compatible with the A1 lamps, so we will have replacement PCBs for those when they reach the end of their useful life.

We were delighted during the build of Tornado when supporters came forward and offered us original Stones housings that allowed us to fully fit the engine.  We now have a requirement for a further two housings for the P2.  We would be pleased to receive any offers of housings that will allow us to meet this requirement.  They need to be the same design as on Tornado and ideally have a clear lens.  Please get in touch if you have one that you would like to see fitted to the P2!

A Stones marker lamp of the type required for No. 2007. – David Elliott

Work on the electrical conduit system for the tender is currently paused, awaiting the next phase of work on the East Coast Digital Project, which we expect to include installation of the European Train Control System (ETCS) on Tornado.  As mentioned in TCC 58 we are taking the opportunity to incorporate several of the P2 electrical system design improvements into the design for Tornado, especially around the arrangements that permit cab removal.  Once this is agreed we will import the A1 design back into the P2 and complete the conduit work.

The A1 Steam Locomotive Trust has announced a new £40,000 appeal – The Turbogen Club – to fund the first of the two turbo-generators required to power the modern electrical system necessary for No. 2007 Prince of Wales to operate on the Network Rail main line.  To find out more and to join the club follow this link.