The invention discloses a blade tip gap measuring
system based on AC discharging. The blade tip gap measuring
system comprises an AC
numerical control adjustable
exciter, a discharging probe, a current measurement conversion module, and a
data processing module. One end of the discharging probe is flush with the inner wall of a casing. The other end of the discharging probe is exposed outside the casing. The part, inserted into the casing, of the discharging probe is wrapped in an insulated layer. The high-
voltage end of the AC
numerical control adjustable
exciter is connected with the discharging probe. The
cathode of the AC
numerical control adjustable
exciter is connected with the center of a rotor blade via the current measurement conversion module. The current measurement conversion module is connected with the control end of the AC numerical control adjustable exciter via the
data processing module and is used for controlling the amplitude and the output of the output
voltage of the AC numerical control adjustable exciter. A measuring method comprises drawing a relation curve between discharging initial
voltage and blade tip gaps, measuring the discharging initial voltage of a rotor blade to be measured, finding out a corresponding blade tip gap value according to the relation curve, namely the blade tip gap of the rotor to be measured. The blade tip gap measuring
system is good in practicality, convenient to install and use, simple in operation, short in
voltage regulation time, and high in efficiency.