Capacitance probe

Abstract: A point level sensor senses capacitance of a material in a vessel to determine level. The capacitance is input to a comparator which is part of an oscillator circuit developing a square wave signal having a period corresponding to capacitance. A microprocessor includes an internal counter which determines the period of four pulses to determine an average period. The microprocessor drives relay circuits providing discrete outputs according to specific precalibrated levels to be sensed. The point sensor includes a self-test mode which operates once per second to test for shorting of the probe, expected frequency response and an open probe.

Abstract: A circuit for measuring capacitance of a capacitor that includes a PMOS device, a NMOS device, a first terminal, and a second terminal. The drains of the PMOS and NMOS devices are connected to each other, one end of the first terminal is connected between the drains of the PMOS and NMOS devices, and the other end of the first terminal and one end of the second terminal are connected respectively to two sides of a capacitor. The invention also discloses a method for measuring capacitance of a capacitor by using the circuit mentioned above.

Abstract: A capacitor is provided having a tough surface portion which prevents cracking that tends to occur when the capacitor is built-in or surface-mounted on a wiring board. A ceramic sintered body of the capacitor includes a capacitor forming layer portion, a cover layer portion and an interlayer portion. The capacitor forming layer portion has a laminated structure wherein ceramic dielectric layers and inner electrodes connected to a peripheral portion of capacitor via conductors, are alternately laminated. The cover layer portion is exposed at a surface portion of the ceramic body and has a laminated structure wherein ceramic dielectric layers and dummy electrodes not connected to the capacitor via conductors, are alternately laminated.

Abstract: Systems, methods, and apparatus for monitoring clearance in a rotary machine are provided. According to one embodiment of the invention, there is disclosed a method for monitoring clearance between a rotatable member and a stationary member in a rotary machine. The method may include providing a flex circuit capacitance sensor. The flex circuit capacitance sensor may include at least one capacitance sensing layer, at least one shielding layer adjacent to the capacitance sensing layer, at least one ground layer adjacent to the shielding layer, and a set of conducting leads connected to the capacitance sensing layer. Further, the method may include mounting the capacitance sensor between a portion of the rotatable member and a portion of the stationary member. Clearance may be determined between the rotatable member and the stationary member based at least in part on a capacitance indication from the capacitance sensor.