Raynes Park Electrical Control Room (SEG)
Wednesday 17th August 2016
Organised by the Southern Electric Group, the group, including BLS members, met at the station then took the short walk to the Electrical Control Room, opened on 2 Oct 1955 as part of the 'Change of Frequency Scheme'. As part of this Lewisham (18 Apr) and Selhurst (21 Aug) opened the same year. All three are housed in low brick buildings containing a 27ft x 8ft mimic diagram showing track layouts and cable runs with indicator keys and lamps to control the 33kV three phase supply fed from the National Grid and the power supply. Raynes Park has 28 sub stations; the indicator lamps only light for faults. To minimise 750V DC supply 'ripple' each of the three AC phases is rectified separately by a silicon bridge rectifier.
The rotary converters used in the original electrification are not electric motors driving a generator as sometimes thought. A rotary convertor is a synchronous motor driving a set of heavy-duty electrical contacts. The motor spins in time with the AC frequency and causes the contacts to reverse the connections to the load just at the point that the voltage is at zero. Consequently, the contacts do not have to switch a large current, but they need to be able to carry a large current to supply the third rail.
The remote control system uses what was then standard 'General Post Office' telephone exchange electro-mechanical equipment supplied by the General Electric Company and it still works! This is split between two rooms at opposite ends of the building to maintain at least a partial supply in case one fails. Likewise, although the control room can be one person operated, at least two have to be on duty.
Raynes Park controls Richmond to Gunnersbury, the Waterloo & City Line, Wimbledon Depot, Waterloo to Egham, Leatherhead, Guildford via Oxshott/Epsom and the branches to Hampton Court, Chessington South and Shepperton. Its functions are expected to be transferred to Basingstoke ROC after 2020. Thanks to NR for allowing access to this little known area of the railway operation and to Stuart Hicks for arranging it; a collection raised £55 for 'Reach' the local staff's nominated charity.
