Exam Question

### (a) Types of Temperature Sensing Devices for Remote Indication
For a remote temperature indication system on board a ship, the sensor must convert a physical temperature change into an electrical signal that can be transmitted to a control room or bridge. Three primary types suitable for this purpose are:
1. **Thermocouples:** These are widely used for high-temperature applications such as main engine and generator exhaust gas, and boiler furnace temperature monitoring. They operate on the Seebeck effect, generating a small voltage proportional to the temperature difference between two junctions.
2. **Resistance Temperature Detectors (RTDs):** These are highly accurate and stable sensors used for measuring temperatures of critical systems like main engine lube oil, jacket water, scavenge air, and cargo temperatures. They operate on the principle that the electrical resistance of a pure metal (commonly Platinum, e.g., Pt100, Pt1000) changes in a precise and repeatable manner with temperature.