What Are The Issues Caused By Motor Run Capacitors? How to Test It

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Motor Capacitors such as motor run capacitors often cause problems and due to this they may cause problems with fuse and other stuff.

Have you ever come across a power problem where once you switch on the power supply and the fuse blows? You have checked all the components in the power (primary) and secondary section and all the components seem to be ok! Where is the fault? A fuse blown is usually caused by a shorted bridge rectifier, defective posistor, power transistor or FET, shorted primary winding of switch mode power transformer, shorted secondary diode etc. But in this article I’m gone to show you another secret of electronic troubleshooting tips.

How To Know It Is Your Motor Run Capacitors That Are Causing Issue?

I got frustrated as to the cause of the power problem. Every time I switch on the power supply the fuse blows immediately (the fuse becomes dark color and this indicates that there is a major short circuit in the power supply). I have checked all the components in the power supply and can’t find the culprit! What I do is I desolder all the suspected parts one by one and replace them with a known good component. I eventually found the cause of the power supply problem. Guess what? It was the main filter capacitor (220 microfarad 400 volt). After replacing the filter cap the power supply worked perfectly fine. I begin my detective work to find out why this capacitor can cause the fuse to blow even though I already confirmed it is OK with my meters.

What I Used?

The meters that I used to check the filter cap were analog meter, digital capacitance meter and esr meter. In this article I will not explain about how to check capacitors or testing capacitors and how capacitors work. I believe most of you know how to check capacitors and also generally use this type of meter. Measured with analog it showed capacitor charging and discharge, with digital capacitor tester it showed around 220 microfarad and with esr meter it showed low esr reading!

This proved that the bad capacitor breakdown when under full operating voltage. Then, how do I confirm that this filter capacitor is faulty? By using an analog insulation tester. When I connected the faulty cap to the meter and pressed the go button-it showed a very low resistance and this proved a short circuit between the plates when voltage was applied! There is nothing to do with bad electrolyte.

A good capacitor will just show a charge and discharge in the insulation meter just like you are checking a capacitor using an analog multimeter. In the market there are quite a number of ranges that you can buy. It has a range of 50v, 100v, 250v, 500v, 1000v and even 5000v! If you want to test a capacitor of 100 microfarad 160v then you have to select 100v. If you select 250v, it will blow your capacitor that is under test.

Advantages Of Using A Test Equipment

If you have the testing equipment such as the lc meter LC102 OR LC103, these meters have the capabilities of checking any type of capacitors with four tests:

  • Testing for capacitor values
  • Checking for leakage
  • Equivalent series resistance (ESR) and
  • Dielectric absorption

It can check aluminum electrolytic capacitor, film capacitor, ceramic, high voltage capacitor, etc.

Capacitors, like batteries, are often the shadow heroes of electrical circuits that store voltages that can be emitted on demand. Capacitors are usually discarded until they fail and the entire device fails or malfunctions. A digital voltmeter, also known as a multimeter, is very useful for testing whether a capacitor is carrying an electric charge. This process is easy and fast.

How To Check The Motor Run Capacitors Using A Volt Meter?

Step 1

As a first step, you need to empty the capacitor. Using wires, you can connect the two terminals of a capacitor, make them jump, and then discharge the accumulated voltage.

Step 2

In the second step, you need to configure the voltmeter to get readings in the higher ohms range. It’s somewhere between 10k and 1m ohm.

Step 3

The third step you need to do is to bring the multimeter wire in contact with the wire opposite the capacitor. Capacitors are essentially directional, so you need to be sure to distinguish between negative and positive leads.

Step 4

The fourth step is to monitor the counter display. The display reads one of the two results. If you start from scratch, you should start moving towards infinity and quickly settle there with an infinite charge from the multimeter’s battery. Capacitors are definitely in good working order. However, if you find that the scale is still zero, you know that the capacitor is not charged. So that means bad.

Final Step

The last step that you should do is to check the results with a similar type of working capacitor known in a way to compensate for anomalies in the meter. So, you can easily test a capacitor with a voltmeter by following some of the tips above.

For more info on all the different types of capacitors visit https://ambercaps.com/