Referring to mentioned reference, the calculations and tests provided parameter values and the source voltage. To calculate the stator to rotor capacitance, two parallel conductors were analyzed with a separation equal to the distance between the centers of the conductors. This value was modified to reflect the number of stator slots and slot opening area. To establish the rotor to frame capacitance, the rotor and stator were considered to be parallel cylinders with an air gap. Figure below shows the Crf as a function of horsepower for 4 and 6 pole motors. The bearing film capacitance was calculated assuming a spherical construction for the ball with respect to the race surface. 
A typical value for the ball bearing capacitance is 190 pF. The calculated values for the test motor and bearing are contained in Table below. 
Tests were performed to establish the accuracy of the above calculations. With the stator unexcited and the rotor coupled to a drive motor, measurements of the effective capacitance from rotor to frame were made with a RLC meter at various speeds. The tests consistently produced a capacitance of 1400 pF. This value represents the equivalent of Csr // ( Csf + (Crf //Cb)). Although the Cb depends on the speed of rotation, the invariance of the measurement suggests Crf dominates. The Csf is obtained by measuring the capacitance from the stator terminals to frame with the rotor removed. To establish the Csr, measurements were made of the effective capacitance from stator terminals to frame with rotor shaft and frame connected. The Csr is obtained by subtracting Csf . Figure below shows Csr for the test motor as a function of frequency. 
Finally, the bearing impedance Zl was measured as a function of rotational speed, the results of which are shown in Figure below. 
This in combination with the measured value of Cb allowed for the determination of Crf . The measured values are included in mentioned Table. Verification of the parameter values consisted of tests with the insulating sleeve grounding strap open circuited and the drive operating at various frequencies at no-load. The stator neutral to ground voltage and rotor voltage to ground were measured; the stator voltage from the neutral of the stator windings and the rotor voltage from the rotor brush attachment. Typical results of the tests are displayed in Figure below. 