A triple-expansion engine passes steam through high-, intermediate- and low-pressure stages before exhaust, while a directly coupled multipolar dynamo converts shaft input to electrical output. This calculator shows only a user-entered shaft-power envelope.
Triple-expansion Engine Power-band Comparison Calculator
Enter a mean shaft-power value, an observed valve-gear clearance and a selected half-band percentage. The tool reports direct arithmetic only; it does not predict steam-engine, dynamo or clearance-loss performance.
Equation Used
- Entered power is treated as a mean shaft-power value for arithmetic display.
- The entered percentage is a symmetric user-selected half-band.
- The clearance input is an independent observation and is not converted to efficiency or loss.
- The illustrated cylinders are schematic and their relative sizes are not dimensioned.
- No steam state, cylinder geometry, indicated work, mechanical loss, generator efficiency, voltage, current, field, commutation, load response, stress, wear or safe limit is modeled.
Serial Expansion and a Direct-Coupled Dynamo
A triple-expansion reciprocating engine expands steam successively through high-, intermediate- and low-pressure cylinders. U.S. Patent 2,066,151 describes those three cylinders arranged for serial steam expansion in that order.
A multipolar dynamo places multiple field poles around a rotating armature. U.S. Patent 520,781 describes a directly driven multipolar armature and illustrates a sixteen-pole machine. The drawing shows the engine stages and dynamo together schematically; it does not simulate their performance.
What This Calculator Represents
The tool takes an entered mean shaft-power value and an entered percentage band, then reports symmetric arithmetic bounds. A valve-gear clearance value is displayed independently.
Clearance and power are shown independently. Relating them would require measured valve events, indicator data, speed, load and a validated engine model.
Entered Power Envelope
low bound = mean power × (1-r/100)
high bound = mean power × (1+r/100)
displayed clearance = entered clearance
r is a user-selected half-band. These bounds do not represent measured ripple, confidence limits, electrical output or equipment ratings.
Worked Arithmetic Example
For entered mean shaft power 200 kW and a selected 15% half-band, the displayed bounds are 170 kW and 230 kW. An entered 0.50 mm clearance is shown as 0.50 mm and does not change those values.
Model Boundary
- Calculated: symmetric percentage bounds around an entered mean value.
- Displayed: an independent entered clearance observation.
- Not calculated: indicated or brake power, steam consumption, cylinder balance, valve timing, clearance loss, torque ripple, dynamo efficiency, electrical power, voltage regulation, commutation, inertia, vibration, component condition, suitability or safety.
Frequently Asked Questions
Does clearance reduce power by a fixed percentage per millimetre?
No such relationship is used.
Is the selected band predicted torque ripple?
No. It is only a user-selected arithmetic band.
Are the low and high values electrical output?
No. They are bounds around entered shaft power.
Does the illustration specify cylinder bore ratios?
No.
Are dynamo efficiency and voltage regulation included?
No.
Can this calculator diagnose or rate a historical engine-generator set?
No.
References
- U.S. Patent 2,066,151, Reciprocating steam engine: high-, intermediate- and low-pressure cylinders arranged for serial expansion.
- U.S. Patent 520,781, Dynamo-electric machine: directly driven multipolar armature and illustrated sixteen-pole field.
- U.S. Patent 455,790, Dynamo electric machine or motor: multipolar dynamo-electric machine construction.
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