Simple checks without a true capacitance meter
– Aluminium electrolytic capacitors tend to have high capacitance and poor leakage.
– A multimeter in a resistance range can detect a short-circuited capacitor or one with high leakage.
– An analog multimeter in a high resistance range can provide a crude idea of capacitance.
– Interpreting results requires experience or comparison with a good capacitor.
Simple and non-bridge meters
– Many DVMs have a capacitance-measuring function.
– DVMs charge and discharge the capacitor under test to measure capacitance.
– DVMs can measure capacitance from nanofarads to a few hundred microfarads.
– Measurement of rotary capacitors is possible with a digital multimeter.
– Capacitance can also be measured by passing a known high-frequency alternating current through the device.
Bridges
– Sophisticated instruments use bridge circuits to measure capacitance.
– Varying the values of the other legs in the bridge determines the value of the unknown capacitor.
– Bridge circuits can measure series resistance and inductance.
– Combined LCR meters can measure inductance, resistance, and capacitance.
– DC bias voltage can be applied in bridge circuits to measure leakage current.
Troubleshooting circuit problems
– Some circuit problems are intermittent or only show up with the working voltage applied.
– Freezer spray can be used to observe the effect on circuit operation.
– Routine replacement of capacitors is easier than arranging measurements in working conditions.
– Specialized instruments can measure capacitance over a wide range and other parameters.
– Low stray and parasitic capacitance can be measured with a low enough range.
Modern bridge instruments
– Modern bridge instruments usually include a digital display.
– Some bridge instruments have go/no go testing for simple automated use.
– Bridges can be interfaced with computers and other equipment for exporting readings and external control.
– Bridges can measure capacitance from picofarads to farads.
– DC bias voltage can be applied and leakage measured directly in bridge circuits. Source: https://en.wikipedia.org/wiki/Capacitance_meter
A capacitance meter is a piece of electronic test equipment used to measure capacitance, mainly of discrete capacitors. Depending on the sophistication of the meter, it may display the capacitance only, or it may also measure a number of other parameters such as leakage, equivalent series resistance (ESR), and inductance. For most purposes and in most cases the capacitor must be disconnected from circuit; ESR can usually be measured in circuit.
