Fachwissen / Technical Subject Knowledge
What the domain tests
Technical subject knowledge questions check whether you can apply core concepts of the relevant technical field to concrete situations, not whether you can recite definitions. Expect questions on measurement principles, units and error sources, system components and their interaction, and the interpretation of technical documentation such as datasheets, standards extracts and test reports. You should be able to explain why a value is plausible, not just calculate it.
Concepts to master
Be comfortable with SI units and prefixes, unit conversion, rounding and significant figures. Understand the difference between accuracy and precision, systematic and random error, and how tolerance chains accumulate. Know how to read a characteristic curve, distinguish nominal from actual values, and identify which parameter limits a system. Familiarity with typical safety margins and derating logic helps in scenario questions.
Typical traps
- Mixing up units (mm vs cm, kW vs kWh, bar vs Pa) and forgetting to convert before comparing.
- Reporting more decimal places than the input data supports.
- Confusing a specification limit with a measured value, or a typical value with a guaranteed minimum.
- Ignoring ambient conditions under which a datasheet value was determined.
Worked example
A sensor is specified as 0.5 % of full scale on a 0–200 bar range. Full-scale error is 0.005 × 200 = 1 bar. If the reading is 40 bar, the relative error at that point is 1/40 = 2.5 %, not 0.5 %. Rule of thumb: percentage-of-full-scale errors are largest in relative terms at small readings, so always ask at which point the error is evaluated.