basics, high pressure superheated steam, supplied by water tube boilers [2 OFF]-in the boiler room, to a steam turbine plant-" Turbines One high pressure unit, one low pressure unit, usually side by side, in the engine room, the turbine output shafts are connected to a large reduction gear box [Usually triple reduction], to reduce the turbine speeds from some 1500, 2000 revs per minute to the shaft speed of 106 to 115 RPM-Revs per minute, on a single shaft usually. Some time two complete engine and gear boxes are fitted to supply a two shafted vessel. In the case of the navy the propeller is specially designed and the ship could attain a speed in excess of 30 Knots. IN a Turbo electric ship usually a T2 Tanker the 2 boilers where in the boiler room, suppling either one combined High Pressure Low pressure steam turbine with superheated steam, exhausting as a normal turbine plant to a main condenser. Now the turbines through a simple box, are connected at their output speed 1500/3000 rpm- HP/LP to a huge electric generator ( I cannot remember if it was generating alternating or direct current, the electric current was directed by power cables through a propulsion electric switchboard for controlling then cables to a shaft motor-Usually a single motor connected directly to the tail/propeller shaft.=output speed 100-112 rpm revs per minute. What does require a little more understanding, which you may get from a web site describing a T2 tanker power plant, as to how the shaft speed was controlled? In a traditional plant steam turbines/gear box out the speed of the turbines was controlled by the amount of steam/pressure supplied direct to the HP Turbine, by a steam control Valve. In a Turbo electric plant one could either control the turbine motor shaft output by frequency [Synchronous-Alternating current= generator Motor AC] or by generator. Motor relative speeds by Direct Current DC, Commutator speed control. IN WW2 the americans could easily manufacture produce electric plant, and turbines, but not the slow speed diesel Main Engines in the quantity required for the allied shipping that was required.
turbine electric engines
I sailed on various ships and companies from 1954 till 1961 as galley boy to chief cook and the ships had Doxford, B&W, steam piston engines, turbines and turbine electric engines. I have a mild interest in engines and understand all types of engines except turbine electrics. So can you engineers out there tell me the advantage or not and how they work in simple terms are they more effecient more economical, faster etc. I was on the Beaverglen and Beaverdell with the turbine electrics.
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You miss ,one capital cost difference Capt C. The conventional steam plant requires an astern turbine. Less in both cost and efficiency but a significant cost nonetheless.
Interesting on DC. Were there any turbo electric with DC propulsion? I know of diesel electric DC but of relatively recent viintage. The T2s were ac. The motor ran principally as synchronous but was started asynchronously using the short circuited field coils as the 'cage'. The supply was not mucked about with to produce speed control but was simply done by controlling the alternator speed. Reversing done as with any AC motor. Stop, change over two phase, restart. The propulsion electrical power chain was also used for the cargo pumps The normal electrical supply was provided by separate turbo generators operating at ?V/?Hz.
Operators would almost certainly experienced the phenomenon of 'pole-slip'. If the motor was changed to synchronous configuration before being as close to synch speed as possible it would not stay 'in sync'. coupling the rotor with the staor intemittantly as it and the stator field turned at different speeds. The pulses would rock the vessel (I have never heard this myself but a senior electrical colleague says it is spectacularly unmissable. Two vessel types amongst others missed from my CV are T2s and free-piston gasifier gas turbines.
Interesting on DC. Were there any turbo electric with DC propulsion? I know of diesel electric DC but of relatively recent viintage. The T2s were ac. The motor ran principally as synchronous but was started asynchronously using the short circuited field coils as the 'cage'. The supply was not mucked about with to produce speed control but was simply done by controlling the alternator speed. Reversing done as with any AC motor. Stop, change over two phase, restart. The propulsion electrical power chain was also used for the cargo pumps The normal electrical supply was provided by separate turbo generators operating at ?V/?Hz.
Operators would almost certainly experienced the phenomenon of 'pole-slip'. If the motor was changed to synchronous configuration before being as close to synch speed as possible it would not stay 'in sync'. coupling the rotor with the staor intemittantly as it and the stator field turned at different speeds. The pulses would rock the vessel (I have never heard this myself but a senior electrical colleague says it is spectacularly unmissable. Two vessel types amongst others missed from my CV are T2s and free-piston gasifier gas turbines.
T2 Tankers like the Mahout were used for several years post world war2 in Norway to supply power until the infrastructure was repaired. They must have been producing DC electricity as Norway uses DC power.
T2 Tankers like the Mahout were used for several years post world war2 in Norway to supply power until the infrastructure was repaired. They must have been producing DC electricity as Norway uses DC power.
T2 Tankers like the Mahout were used for several years post world war2 in Norway to supply power until the infrastructure was repaired. They must have been producing DC electricity as Norway uses DC power.
T2 Tankers like the Mahout were used for several years post world war2 in Norway to supply power until the infrastructure was repaired. They must have been producing DC electricity as Norway uses DC power.
T2 Tankers like the Mahout were used for several years post world war2 in Norway to supply power until the infrastructure was repaired. They must have been producing DC electricity as Norway uses DC power.
T2 Tankers like the Mahout were used for several years post world war2 in Norway to supply power until the infrastructure was repaired. They must have been producing DC electricity as Norway uses DC power.
So basically the turbine runs a generator which turns the the screw but what advantage over conventional turbine. There must be more machinery are they economical more reliable more efficient faster speeds Etc. There were five ships built in the U.K towards the end of the war for Canadian Pacific perhaps they were the only engines available of which were Beaver boats on which I sailed on two.
I did read once that during the 2nd WW the reason for Turbo Electric drives was because of the shortage of gear cutting equipment to cut the gears for conventional gearboxes
IanB
IanB
Thank you Gentlemen for your information summing up it appears that turbine electrics were more readily available W.W.2 and after. were they more reliable easer to maintain.I sailed on two TEV.s Beaverglen and Beaverdell also one strait turbine Beaverford which was a previous Empire Boat and what I can recollect plying the North Atlantic they were quite reliable.I did read once that during the 2nd WW the reason for Turbo Electric drives was because of the shortage of gear cutting equipment to cut the gears for conventional gearboxes
IanB
All 'recent' New Zealand Inter-Island Express Lyttelton - Wellington ferries (Rangatira(s) of 1931 and 1967, Hinemoa, Maori and Wahine were all turbine-electric propulsion. One major reason given being that the system allowed more or less instant change from ahead to astern which was apparently beneficial in the locations in which they operated. There is an internet claim that Rangatira (1931) could go from 22 knots ahead to 17 knots astern in five minutes.
There is also an excellent website on naval vessels which includes all manner of technical matters on armament, armour gunnery etc etc. It included an article on the advantages/disadvantages of turbine - electric drive versus traditional steam turbine as they applied to American battleships . Sadly I can no longer find the site*.
Geoff (YM)
*Edit: this might be the site: History and Technology - Turboelectric Drive in American Capital Ships - NavWeaps
There is also an excellent website on naval vessels which includes all manner of technical matters on armament, armour gunnery etc etc. It included an article on the advantages/disadvantages of turbine - electric drive versus traditional steam turbine as they applied to American battleships . Sadly I can no longer find the site*.
Geoff (YM)
*Edit: this might be the site: History and Technology - Turboelectric Drive in American Capital Ships - NavWeaps
The plant that Joseph Czarnecki describes has constant speed generators and variable speed motors. With the technology of the time this necessitates the power delivery to be DC. The T2 controls speed much as a conventional steam plant by controlling the turbine speed/frequency.
I suspect an instant change from ahead to astern (or vice versa) might also also be problematic for the T2. The starting current with the motor turning in the opposite direction will be very high (it is probably a very long way from an amp or two anyway) and with any significant way on there might be a tendency for the motor speed to dip too far at the instant of changing to synchronous and so increasing the chances of a pole-slipping 'misfire'.
The T2 provided DC separately for the excitation of propulsion alternator and motor but I doubt it would have been much use in terms of a floating power station. I am also surprised that anywhere in the west had DC distribution on anything more than an isolated locality by mid-1900s.
With the need for more flexibility in an effort to 'be greener' DC for power transmission may/will see increased use. I don't know what the bunkering infrastructure was for diesel vessels (cited earlier as an alternate candidate in replacement wartime tonnage but it will have seen steamers as their bread and butter will coal still widely. This must also, along with diesel 'qualified' E-R staff in the choice.
I suspect an instant change from ahead to astern (or vice versa) might also also be problematic for the T2. The starting current with the motor turning in the opposite direction will be very high (it is probably a very long way from an amp or two anyway) and with any significant way on there might be a tendency for the motor speed to dip too far at the instant of changing to synchronous and so increasing the chances of a pole-slipping 'misfire'.
The T2 provided DC separately for the excitation of propulsion alternator and motor but I doubt it would have been much use in terms of a floating power station. I am also surprised that anywhere in the west had DC distribution on anything more than an isolated locality by mid-1900s.
With the need for more flexibility in an effort to 'be greener' DC for power transmission may/will see increased use. I don't know what the bunkering infrastructure was for diesel vessels (cited earlier as an alternate candidate in replacement wartime tonnage but it will have seen steamers as their bread and butter will coal still widely. This must also, along with diesel 'qualified' E-R staff in the choice.
Norway transmits DC electrical current to the UK and it is converted to AC in Northumberland today.
Wiki gives that as the longest undersea HVDC link in the world and as with all recently built it can act to either import or export. Converter stations at either end of the cable modify the current as required to link the two AC national networks together. The economics for using DC links is down to the losses on any given cable route with those subsea being greater. The considerable cost of converter stations being the extra variable in the cost equation. The UK has several other HVDC interconnectors (see https://gridwatch.co.uk for a decent description and current import/export status - pardon little leckie chuckle). Wiki also has a much longer list of links current and historic as List of HVDC projects - Wikipedia. (Our little link is AC and not worthy, evidently, of gridwatch's consideration).
Why are HV DC losses lower than HVAC? If it is significant then maybe we could increase National Grid capacity by going down that route (Outages for conversion permitting)Wiki gives that as the longest undersea HVDC link in the world and as with all recently built it can act to either import or export. Converter stations at either end of the cable modify the current as required to link the two AC national networks together. The economics for using DC links is down to the losses on any given cable route with those subsea being greater. The considerable cost of converter stations being the extra variable in the cost equation. The UK has several other HVDC interconnectors (see https://gridwatch.co.uk for a decent description and current import/export status - pardon little leckie chuckle). Wiki also has a much longer list of links current and historic as List of HVDC projects - Wikipedia. (Our little link is AC and not worthy, evidently, of gridwatch's consideration).
Whether losses is the correct term in that with an undersea link the capacitance is much higher (effectively the 'plates' are within an inch of one another, the seawater being more conductor than dielectric. This 'loss' is reactive but that still contributes to the voltage drop as does the real component so would require much more copper to minimise it. In terms of aerial cables that component remains a factor but can be addressed more cheaply (electrickery ashore is not my forte despite my most useful Saudi Shields instructor being brought up a CEGB man) I think tap- changing transformers and switchable reactances are part of the management. (I have a book and may revert if this is completely bollockular).
DC would have lower losses but the cost of converters where ever you now see substations would be a vast expense.
DC would have lower losses but the cost of converters where ever you now see substations would be a vast expense.
One other issue which the experts on the site can elaborate on is the element of ship design. Turbo-electric installation allowed a different layout of plant. I believe the Normandie was an example of this?Thank you Gentlemen for your information summing up it appears that turbine electrics were more readily available W.W.2 and after. were they more reliable easer to maintain.I sailed on two TEV.s Beaverglen and Beaverdell also one strait turbine Beaverford which was a previous Empire Boat and what I can recollect plying the North Atlantic they were quite reliable.
One point which I don;t think has been covered here is that turbo-electric installations allowed avery different plant layout in the ship. Perhaps the architects and engineers on the forum can elaborate as to the advantages. Also, my impression is that the French were proponents of this philosophy eg SS Normandie. My view is that turbo-electric installation's advantages are (i) ability for full power in reverse; (ii) quieter (iii) more easily controlled (iv) more easily maintained (v) elimination of astern turbine (vi)(in the case of multiple screws) all propellers to operate even if one engine was not running . Disadvantages (which I think are less important) (i) overall installation was heavier than conventional turbines; (ii) slightly less efficient at high speed; (iii) possibly more expensive but I am not certain about that .
A fascinaing thread. I can't add anything to the shipboard side of it but I know in New Zealand, the South Island Mackenzie Basin Hydro Lakes generate their power as AC, convert it on site to DC for Transmission to the North Island where it is converted back to AC for distribution to the domestic system. I've always understood this was due to less transmission loss with DC than AC.
I was told DC transmits straight along the cable without trying to escape. AC is the wayward one trying to escape and mostly moves along the outer edges of the cores. I have been told the connector transmission from Norway through the converter station at the UK end only loses 3% of the electrical power.
One for Varley.
A few years ago we had somebody knock on our door from SSE/SEB the electricity supplier wanting us to fit a gizmo on our power supply to drop the voltage, claiming that it would save us money.
I said if you drop the voltage then the current will increase or things will run slower if motor driven and might effect computers, so no I don't want one. I suggested he fit one at the distribution transformer if its that good then everybody benefits.
Later on I thought was it a power factor correction device. Only on one phase? The only motors that are running continously are the fridge and freezer. The washing machine and grundfoss pump for the heating are ocassional.
So Varley was it snake oil he was trying to flog or give away? He never tried again and I don't think anbody had one fitted that I know of.
How would you really know it was saving you money as each season is different each year.
A few years ago we had somebody knock on our door from SSE/SEB the electricity supplier wanting us to fit a gizmo on our power supply to drop the voltage, claiming that it would save us money.
I said if you drop the voltage then the current will increase or things will run slower if motor driven and might effect computers, so no I don't want one. I suggested he fit one at the distribution transformer if its that good then everybody benefits.
Later on I thought was it a power factor correction device. Only on one phase? The only motors that are running continously are the fridge and freezer. The washing machine and grundfoss pump for the heating are ocassional.
So Varley was it snake oil he was trying to flog or give away? He never tried again and I don't think anbody had one fitted that I know of.
How would you really know it was saving you money as each season is different each year.
Basically snake oil I think. Reducing the voltage (assuming this is done losslessly) would reduce the power taken by resistive loads (toaster, heaters and filament lights). Your few AC motors will consume about the same power. Not sure about universal motors (vacuum cleaners motors for instance - with brushes).
You meter measures power and so power factor should not affect it. however an ammeter, inserted for demonstration purposes, might be used to demonstrate the reduction in current that power factor correction might provide but that would be misleading as the reactive portion affected does not influence the KWH meter What you will save in the poser of those resistive loads you will have to weigh against having them on longer (in the case of lights, more of them to provide the same light.
I wonder if he was from the REC and not from some mafialike traders seeking access.
(The universal motor case might be interesting. The speed is determined by the difference between the applied voltage at the brushes and the back EMF generated by the armature turning in the magnetic field. A weaker field meaning lower back EMF therefore increasing the speed (power) for a given applied armature voltage. Who wins out escapes me but there is probably a google phrase that would solve it for us).
(I have had an afternoon on the fizz so I May have to eat some of that later).
You meter measures power and so power factor should not affect it. however an ammeter, inserted for demonstration purposes, might be used to demonstrate the reduction in current that power factor correction might provide but that would be misleading as the reactive portion affected does not influence the KWH meter What you will save in the poser of those resistive loads you will have to weigh against having them on longer (in the case of lights, more of them to provide the same light.
I wonder if he was from the REC and not from some mafialike traders seeking access.
(The universal motor case might be interesting. The speed is determined by the difference between the applied voltage at the brushes and the back EMF generated by the armature turning in the magnetic field. A weaker field meaning lower back EMF therefore increasing the speed (power) for a given applied armature voltage. Who wins out escapes me but there is probably a google phrase that would solve it for us).
(I have had an afternoon on the fizz so I May have to eat some of that later).
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