The LCSR test involves heating the sensing element of the temperature sensor with an electric current. For RTDs, a DC current goes to the RTD extension leads to cause internal heating in the RTD sensing element. A Wheatstone bridge is a part of the RTD test and the electrical test current steps from a few milliamps to 40 to 80 mA to perform the LCSR test. The transient that results from the internal heating registers at the output of the Wheatstone bridge and then, after digitization, provides the response time of the RTD and also for RTD diagnostics purposes. For thermocouples, an AC current of about 0.2 to 2 amps works depending on the thermocouple and its installation. The current wires to the end of the thermocouple extension wire for a few seconds and then switched off as the thermocouple output records. This output undergoes analysis to obtain the thermocouple response time or diagnose thermocouple installation problems. The LCSR test causes the sensing element of the RTD or thermocouple to heat up about 10°C to 20°C above the ambient temperature depending on the amount of applied current and the sensor ability to dissipate the heat.