I measured the capacitance of PMC's PZT to be 0.23 uF.
The PZT actuator attached to PMC middle mirror is used to change the total length of the PMC cavity.
It has internal capacitance which effects the TF of the system. The value is used in LISO model to calculate the PMC loop TF.
To measure that, I removed high voltage output from PMC card from the PZT connector on the table,
discharged the PZT with 50 ohm resistor for a minute. Then I used an L-C meter to measure the capacitance.