With the engine’s arrival at the Great Central Railway (GCR) it was possible to couple the engine and tender together for the first time following the overhaul. This allowed us to connect all the existing and new electrical ‘umbilicals’. We now have six of these. Two are new versions of our original Essential Services (ES) and Auxiliary Services (AS) connections. One new one carries the turbogen supply to the ETCS and three others connect all the ETCS equipment on engine and tender together. We were pleased when all the existing and new systems powered-up correctly, proving that all the connections were correctly made.
Our new two-turbogen setup was tested on steam at the end of August. A set of tests under various loads proved both turbogens and all the existing wiring to the AS and ES I/O Panels and their loads. We also successfully tested the new Steel Wire Armoured (SWA) cable which connects the turbogens to the ETCS I/O Panel and batteries. We were very pleased when, for the first time, we had a turbogen directly charging a set of batteries on the A1. Our existing supplies route the turbogen output via our DC-DC converter chargers. This wasn’t possible for the ETCS supply as we wanted to avoid the power loss of the converters.
Tests showed that the fireman’s side turbogen (T1) will deliver an output of 407W at 22V into our new ETCS Load Bank whilst also putting about 2.5A into the batteries. This was an excellent result. The new driver’s side turbogen (T2) does even better. It is almost entirely wired using the new 2 x 6mm2 SWA cable and therefore suffers significantly lower voltage drop on its route from the front of the engine to the rear of the tender. T2 will deliver 568W with about 4A still going into the batteries. At this point it is delivering about 31A, which is close to Meiningen’s absolute maximum specified output of 32A for the Fabeg-design turbogens. This showed that the alternator regulator in a turbogen, when used directly to charge batteries, successfully controls the delivered current to maximise its output without stalling the turbine.
The results confirmed that we have a comfortable operating margin from both turbogens over the expected ETCS power demand. This is good news and confirms that our design does what we intended. Either turbogen can comfortably supply the ETCS demand, with the margin being greater for T2 due to its lower round trip wiring resistance.
Once all the electrical systems were confirmed as working, visits from the Hitachi ETCS team progressively tested all the new ETCS equipment, together with the Mk 4 TPWS and Hasler Juridical Recording Unit (JRU). These tests included checks of the Balise antennas under the engine and tender when towed over test Eurobalise transponders fitted to the track. All the systems worked as designed.