Working Principle and Measurement Methods of Capacitance and Inductance Meters

发布时间：2022-12-16

We all inevitably use capacitors in our daily lives and at work. Simply put, they’re like batteries—though we wouldn’t call them that. Whenever you have a capacitor, you’ll also need a tool to measure it. Below, we’ll explain the operating principle of a capacitor–inductor tester, hoping it will be helpful to you.

　　How does a capacitance and inductance tester work?

　　Operating principle: By employing synchronous sampling of both the standard capacitor and the capacitor under test, the measurement is unaffected by fluctuations in the supply voltage. Furthermore, the entire measurement process is fully automated, eliminating errors introduced by manual operation. Consequently, the instrument exhibits excellent stability, high repeatability, and reliable accuracy.

Capacitance and Inductance Meter Features:

　　1. When measuring a single capacitor on-site, the connecting leads must be disconnected, which not only involves a heavy workload but also increases the risk of damaging the capacitor.

　　2. Low capacitor output voltage results in a low fault detection rate.

　　3. Measure the inductance of the reactor.

　　The capacitor–inductor tester features a small measurement workload, rapid and straightforward operation, stable performance, high measurement accuracy, and a high fault‑detection rate. In addition, its current‑measurement unit can be used to test electrical equipment such as CVTs and surge arresters, offering multi‑functionality in a single instrument. It is a high‑voltage measurement device.

　The operating principle of a capacitance and inductance tester

　　The capacitance–inductance tester measures the capacitive current of a distribution network directly from the PT’s secondary side. Compared with conventional testing methods, this instrument eliminates the need to work on the primary side, thereby removing any associated safety risks. It obviates the need for complex safety precautions and lengthy coordination procedures; simply connect the measurement leads to the PT’s open‑delta terminals to obtain the capacitive current readings.

　　Since the weak heterodyne test signal is injected into the PT via its open‑delta connection, it has no impact on relay protection or the PT itself, thereby eliminating 50 Hz power‑frequency interference. Moreover, the output can withstand an AC voltage of 100 V. If a single‑phase ground fault occurs during measurement, neither the PT nor the tester will be damaged, so no special safety precautions are required. This makes the procedure safe, straightforward, and rapid, with test results that are accurate, stable, and reliable.

　　Measurement Method for Capacitance and Inductance Meters

　　1. Testing small capacitors below 1.10 pF: Because fixed capacitors below 10 pF have extremely low capacitance, the only way to assess them is to use a multimeter to check for leakage, internal short circuits, or breakdown. When measuring, select the R×10k range on the multimeter and connect the two test leads to either pair of terminals; the resistance reading should be infinite.

2.10 pF ~ 001 F fixed capacitor testing: Determine whether charging occurs, thereby assessing its condition. Set the multimeter to the R×1k range. The β values of both types of transistors are above 100, with low leakage current. Silicon transistors such as the 3DG6 can be used to form a Darlington pair. Connect the multimeter’s red and black test leads respectively to the collector (C) of the Darlington pair.

Having read the above, you surely now understand the operating principle of a capacitance and inductance tester.

Capacitance and Inductance Tester

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