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I think I remember a previous post on here with a reason or theory why Oriana was built as a DC ship but don't remember the answer.
I was told that one reason was for pump motor speed control to control flow, this is invalid as there were many refineries and other factories that used motor operated valves to control flow.
The original installation was possibly cheaper, i wouldn't have thought so, but the extra maintenance cost would have outweighed this.
Does anyone know the true reason?
I suspect the reason was tradition, I believe the Oriana was the last D.C. ship built in the UK. It always amazed me how much of the DC was converted into AC and how variable the frequency was! I bought a clock radio from the ships shop, one of those where time is displayed on drop down flags the time keeping was up to 2 hours fast or slow per day.
Where are you from: South Australia
Aug 26, 2017 - 1:42AM
Re: Oriana, why DC.
Was not Oriana's DC installation mainly used due to its ease of speed control for her cranes? Before the advent of thyristor control for AC power, AC speed control was fairly expensive, I should think, using the Ward-Leonard setup. I'm sure I recall hearing that the eight cranes were the prime reason for fitting DC.
(Either that, or Vickers had a job-lot of DC motors they wanted to flog to the Orient Line, lol!)
Speed control for cranes doesn't seem a valid reason, yes speed control for a.c. cranes would be more expensive but greatly outweighed by lower maintenance costs. The cost of just rebrushing the generators would be huge by comparison, reliability and cleaning costs would also be significant. This applied throughout the ship for the lifetime of the ship would be enormous compared to installation costs of cranes.
Not having the faintest knowledge of electrical systems but enjoying the debate, I would venture to suggest Ian Brunton's verdict to be the most likely. I do have a copy of Charles Morris's ( Orient Lines last Naval Architect) fascinating book, ORIGINS, ORIENT and ORIANA which will probably reveal the answer.
One of my last memories is, during the final deadship tow to Japan, of very briefly putting the A/C SUPPLY on to have a good look around the ship with proper lighting.Rather risky with all spaces unoccupied.
I have asked a few of the older hands (not that there are many left now) here at the birthplace of Oriana.
And the concensoius was that is was probably due to who the customers electrical super intendent was at the time she was ordered as Canberra the next liner ordered was AC.
So maybe as Oriana was the last liner Oriant ordered from Vickers in Barrow and all of the Oriant line ships had all been DC. And as Alan suggested they probably had a few DC motors in the spares box.
Where are you from: Barrow
Aug 27, 2017 - 6:41PM
Re: Oriana, why DC.
Don, I doubt that they had a box full of generators sat in a shed. I think it must have been a considered decision and probably, as WAM says, it was simply for speed control of pumps and cranes but a very expensive decision over the life of the ship.
My recollections of Oriana were from 1967 - 8 and that the use of D.C., reasoning was for the motor control, mainly for the FD and ID fans as they, if I remember correctly were 200 hp... How we knew it as well as one of the FD fans blew an armature on starting up for departure San Francisco, 6 hour watches to change it.. In the heat of the California summer.. Oh how we used to love changing the brushes on the generators lying flat bedding brushes... Health and safety then?? The P&O electrical superintendant was an ex GEC Witton, Birmingham, man, whose name I now forget.
An FD fan! you were lucky! We changed an ID fan armature on the Arcadia while at sea with only the daywork crew, swinging a 4 ton armature on 2 ton chain blocks great fun NOT! I thought the Pakistani crew were brilliant at finding "skyhooks" as we transferred one armature out and the Ex Iberia one in. No health and safety no one got hurt but the failed armature slipped off its chain on the last move and fell about 5 feet and ended up "D" shaped.
Where are you from: Land of Jock
Oct 7, 2017 - 8:15PM
Re: Oriana, why DC.
ID fan you were lucky.
We had to change the port main propulsion alternator rotor on Canberra took three weeks and to be honest it was a team of specialists that flew out as the stator windings where blown hell of a job that was.
There is a photo of me Sat inside the stator somewhere on this site.