Turbine diagnostics

A turbine speed probe diagnostic system, comprising:

• a speed lead connected to a speed probe and to a speed reading circuit;
• a speed probe diagnostic circuit;
• a first isolation switch connected between the speed lead and the speed probe diagnostic circuit;
• wherein the speed probe generates a speed signal and transmits the speed signal through the speed lead to the speed reading circuit during normal operation of the turbine, the first isolation switch being open during normal operation to isolate the speed probe diagnostic circuit from the speed lead;
• and
• wherein the first isolation switch closes when no speed signal is sensed by the speed reading circuit and the speed probe diagnostic circuit applies a voltage or a ground to the speed lead through the first isolation switch to test for a condition of the speed probe or the speed lead.