🔍 Key Concepts

• Difference between thermocouples (TC) and resistance temperature detectors (RTD) • Which devices are typically self-powered versus requiring an external power source • How centralized bearing monitoring systems on propulsion plants are usually wired and powered

💭 Think About

• Think about which sensor type changes resistance with temperature and which sensor type generates its own voltage with temperature • Ask yourself: in a fixed, permanently installed monitoring system with many bearings, is it more common to use sensors that need a stable excitation current/voltage, or ones that generate tiny millivolt signals? • Consider which type is favored for accuracy and stability in slow-changing machinery temperatures, like bearings, rather than for very high temperature ranges

✅ Before You Answer

• Verify which of the two, TC vs RTD, normally needs an external excitation current to be read • Confirm which option(s) would be realistically used in a central panel monitoring multiple points with long cable runs • Eliminate any option that conflicts with how these sensors are typically powered in industrial/marine applications