Capacitors are part of almost every daily use circuit or devices, from household fans to industrial motors and mcc panels you have to face them everywhere. A faulty or failed capacitor may deteriorate the whole circuit or blow fuse due to a short circuit. In many cases, a malfunctioning complex circuit may create a problem in troubleshooting. In that case, your first priority should be checking its supply and capacitor condition first of all.
In this blog, we’ll tell you how to test a capacitor with a fluke multimeter, because in multimeters fluke meter is the most reliable and result oriented tool. If you have a multimeter other than fluke make sure that it’s a laboratory or manually calibrated before using it.
The process of checking capacitance by fluke multimeter is not much difficult. Almost every digital multimeter comes with a capacitance test function which is the most popular method to test capacitors.
First step is to power off all supplies, remove capacitor if it’s installed in a circuit. Ensure that every type of power has been cut off.
As capacitor is a current storing device, connect a powerfull resistor like 20000 ohms or more with capacitor for some seconds to de energize it completely.
Inspect capacitor physically if it’s broked, crack or any other sign of deterioration.
Now turn on capacitance function by setting fluke meter dial on capacitance mode, you may also has to press a button additionally for going into capacitance mode. Consult your multimeter’s guide for it.
If your multimeter has auto range ability it will adjust capacitance range by itself, otherwise set it manually.
You should have capacitance value more or less near to capacitor rating, but if screen shows “OL” sign that’s may be a sign either the capacitor is faulty or it has a value higher than multimeter’s measurement range.
Safety tips for testing capacitors
Capacitors store electrical charges and they may remain energized for some time even after removal of power sources. They should be properly de energized first to avoid any catastrophe like an electric shock. For this electricians should re check circuit’s or device supplies where they are placed to make sure that every type of power source has been removed. Also, they should wear required protection equipment like gloves and safety shoes.
Capacitors are the backbone of power factor setup in industries to nullify the effect of reactive power (kvar) which is actually a cause of losses. Reactive power may increase electricity bills or even it can overheat cables, transformers and mcc panels. Capacitor banks installed in power factor panels need more careful safety measures.
Another method
If you have a multimeter other than fluke or your meter doesn’t have capacitance measurement ability you may still check capacitors by this method. Resistance function is a must part of every digital or analog multimeter, in this method capacitors are checked by ohms value.
First of all set multimeter to maximum available resistance range. After making sure that capacitor is fully discharged connect meter probes to capacitor terminals. Now note reading which is shown for a short period of time and then disappear or immediately replaced by an OL sign.
Repeat it by connecting and disconnecting the meter with capacitor terminals if you note no change in reading that means capacitor is dead or faulty.
Leo Maxwell is basically an Electrical engineer and hobby tech writer, having 13 years of experience in the electronics and instrumentation industry. He has hands on experience working in various fields like Powerhouses, solar, automotive, and FMCG.
During his career, he has used many power tools and meters in electrical projects. Now his aim is to explain tools and troubleshooting in easy guides to help people. Other then it, leo loves traveling, reading books and DIY tasks.
