Design of capacitance parameter measuring instrument based on virtual instrument

In this paper, a capacitance parameters of high-precision digital measuring instrument was designed, based on the VI (virtual instruments), using LabVIEW software platform and applying current comparison measuring principle. This system possesses current comparison based on Magnetic Potential Balance Principle, PC subject, the integrated data acquisition modules and I/0 control module. Magnetic potential balance has been achieved by controlling coil turns. With the function of PC, accurate test results have been gained. Because of using the closed-loop control and the successive approximation method to control relay, the system achieves equilibrium sharply. This system has been used to test the capacitance of capacitor, dielectric loss value and the inductance of reactor, which has advantages to more accuracy and stability, convenient operation, and adjusting quickly and a wide range of uses.