How the speed of turbine controlled?

17 Nov '18, 23:55

Nov. 17, 2018, 11:55 p.m.
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  1. Throttle Valve - Used in maneuvering or for minor changes in speed. Varies the steam chest presssure.
  2. Nozzle Control Valves - Used to control speed and power requirements without throttling loss.
  3. By-Pass - Used only for excessive power or speed requirements. With throttle and all nozzle control valves wide open, a point is reached where no more steam can pass through the turbine, the flow is limited to the cross-sectional area of the first stage nozzles. In order to increase the flow, valves are installed which by-pass most of the steam around the first stage admitting it to later stage or stages where the nozzle openings and blade areas are larger, thus developing more power.
  4. Speed Regulating Governor - Maintains revolutions constant, either mechanical, mechanical hydraulic relay or direct hydraulic.
  5. Overspeed Trip - Prevents high damaging speeds, generally spring loaded plunger built into turbine shaft. Centrifugal force causes the plunger to fly out and trip a trigger, releasing spring which closes the throttle.
  6. Hand Trip - Used in conjunction with overspeed trip.
  7. Low Oil Trip - When lube oil pressure is reduced to a predetermined point, a hydraulic relay causes throttle to close.
  8. Back Pressure Trip - Some units fitted with diaphragm relay to trip throttle when vacuum is reduced generally not installed on main propulsion units.
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17 Nov '18, 23:59

Nov. 17, 2018, 11:59 p.m.
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