How to measure leakage of capacitors

How do you measure a capacitor leakage current?

These two parameters are related by the equation IL = Vw / Rp, where Vw is the working voltage specification of the capacitor. When measuring capacitor leakage current, the capacitor must be fully charged and stable at its test voltage.

What is a common unit for qualification of capacitor leakage?

This is because the resistance is proportional to the thickness of the dielectric, and inverse to the capacitive area. The capacitance is proportional to the area and inverse to the separation. Thus, a common unit for qualification of capacitor leakage is the product of its capacitance and leakage resistance,usually in megohm-microfarads (MΩ·µF).

How do you measure leakage current?

There are two basic ways to measure the leakage current. First, apply an ammeter in series with the capacitor and voltage source (see Figure 1). Second, apply a voltmeter in parallel with a resistor, and then connect in series to the capacitor and voltage source (See Figure 2). The first method is usually applied to capacitors less than 1uF.

How do you measure a low capacitance capacitor?

The first method is usually applied to capacitors less than 1uF. Low capacitance capacitors have low leakage current; thus, a low current ammeter can measure the current accurately. If the leakage current is high, the ammeter will not able to measure accurately due to the noise and unstability of the charged capacitor.

What is a capacitor leakage test system?

Capacitor leakage test system In this test system, a single instrument, the Model 6517A, provides both the voltage sourcing and low current measurement functions. This instrument is particularly useful for this application because it can display either resistance or leakage current and will source up to 1000V DC.

Why does a capacitor leak?

The dielectric of a capacitor has a large area and a short length. Even if the material is a good isolator there always flows a certain current between the charged electrodes (the current increases exponentially with the temperature). This leakage can be described as a parallel resistance with a high value, an Insulation Resistance (Figure 1.).