... with the fixed resistor and range resistor R1, and the branchwith the RTD and range resistor R2. As the electrical resistance of the RTD changes, the voltageat points X and Y changes. The millivoltmeter ... temperature. To compensate for this change,three and four wire RTD circuits are used. In this way, the same amount of lead wire is usedin both branches of the bridge circuit, and the change in resistance ... functions: indication, alarm, and control. The temperatures monitored may normally be displayed in a central location, such asa control room, and may have audible and visual alarms associated...