Select a backup design for a specified load
The idea
State the required load and operating duration separately; high power alone does not establish enough operating time.
Step by step
- State the required load and operating duration separately; high power alone does not establish enough operating time.
- Use comparable tests to remove designs failing either requirement.
- Compare the eligible designs using the stated cost goal and identify other evidence a real system would need.
Example
System A: supplies 70 W; tested duration 4 h; cost 8 units. System B: supplies 65 W; tested duration 2 h; cost 5 units. System C: supplies 50 W; tested duration 5 h; cost 4 units.
A model backup system must supply at least 60 W for at least 3 h under the stated test. Which eligible system has the lowest listed cost?
Answer
System A
Both power and duration must pass. System A has the lowest listed cost among the qualifying systems; the conclusion applies to these stated trials.
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Write a model power-and-duration requirement. Compare three invented systems and explain one unmeasured factor that could matter.
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