21-06-2012, 07:43 PM
Your thinking of the 1500vdc Sheffield locos that went Dutch.
Yes, the booster set would allow seamless power notching from 0 to 650vdc (later upgraded to 750vdc, the Westinghouse DH27 compressors had a resistance loop fitted which can be seen on the side of the compressor to help them cope with the raised voltage), then would add it's output potential to that of the incoming DC voltage to double the available voltage being fed to the series wired traction motors. The most important parts of the set up were the booster motor start resistances and very important, the current limiting relay which would stop the booster dumping power back into the 3rd rail in the event of failure of the supply due to a short circuit or driving by accident into a current isolation. A roof mounted pan was provided to run off the tram lines within sidings when off the 3rd rail. For such a small loco, they had an enormous tractive effort and ran the Kent boat trains with ease. Cab "bog chain" operated the air powered whistle on the roof.
Eventual fate, some were rebuilt into what became Class 74 by removing the booster and fitting a Paxman diesel inside along with some very complicated electronics that just didnt work. Only one left now, 71001 at Shildon, part of the national collection. The booster sets from the locos went to Wimbledon Depot where they provided power for the depot on a feed seperate from the main line because if there was a short, it would usually happen within a depot.
Yes, the booster set would allow seamless power notching from 0 to 650vdc (later upgraded to 750vdc, the Westinghouse DH27 compressors had a resistance loop fitted which can be seen on the side of the compressor to help them cope with the raised voltage), then would add it's output potential to that of the incoming DC voltage to double the available voltage being fed to the series wired traction motors. The most important parts of the set up were the booster motor start resistances and very important, the current limiting relay which would stop the booster dumping power back into the 3rd rail in the event of failure of the supply due to a short circuit or driving by accident into a current isolation. A roof mounted pan was provided to run off the tram lines within sidings when off the 3rd rail. For such a small loco, they had an enormous tractive effort and ran the Kent boat trains with ease. Cab "bog chain" operated the air powered whistle on the roof.
Eventual fate, some were rebuilt into what became Class 74 by removing the booster and fitting a Paxman diesel inside along with some very complicated electronics that just didnt work. Only one left now, 71001 at Shildon, part of the national collection. The booster sets from the locos went to Wimbledon Depot where they provided power for the depot on a feed seperate from the main line because if there was a short, it would usually happen within a depot.
