A multimeter is a flexible device that can be utilized to check a wide range of electrical parts, together with capacitors. Capacitors are used to retailer electrical vitality and are present in a variety of digital gadgets. Testing a capacitor with a multimeter is a comparatively easy course of, however it is very important observe the right steps to make sure correct outcomes. Earlier than beginning, discharge the capacitor to keep away from {an electrical} shock
The diode setting can be utilized to test for a brief circuit in a capacitor. Join the optimistic probe of the multimeter to the optimistic terminal of the capacitor and the detrimental probe to the detrimental terminal. A brief circuit might be indicated by a studying of zero ohms.
Capacitance mode on the multimeter offers capacitance readings if the capacitor is nice. If the capacitor is dangerous, the multimeter will show “OL” that means “open loop” and point out no connection or an infinite worth.
Setting the Multimeter to Capacitance Mode
To precisely take a look at a capacitor utilizing a multimeter, it’s important to set the system to the suitable mode for measuring capacitance. Totally different multimeters might have barely completely different procedures for setting the capacitance mode, however here is a common information:
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Choose the Capacitance Vary: Most multimeters have a rotary dial or a push-button to pick out the measurement vary. Search for the vary that’s acceptable for the capacitor you’re testing. For instance, in case you are testing a capacitor with a capacitance of 10 μF, choose the vary of 100 μF or larger.
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Set the Multimeter to Capacitance Mode: Multimeters usually have a operate selector change or a push-button to decide on the measurement mode. Find the setting labeled “Capacitance” (often denoted by the image “F” or “C”).
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Join the Check Leads: Join the black take a look at result in the COM (widespread) terminal on the multimeter and the crimson take a look at result in the terminal designated for capacitance measurement.
Further Suggestions for Setting Capacitance Mode
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If the multimeter has an autoranging function, it would routinely choose the suitable capacitance vary and mode.
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Seek the advice of the multimeter’s person guide for particular directions on setting the capacitance mode.
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Earlier than testing a capacitor, it’s good apply to discharge it by shorting its terminals with an insulated device.
Capacitance Ranges for Totally different Kinds of Capacitors
The suitable capacitance vary to pick out depends upon the kind of capacitor being examined. This is a desk on your reference:
| Capacitor Kind | Typical Capacitance Vary |
|---|---|
| Ceramic | 1 pF – 1 μF |
| Electrolytic | 1 μF – 10,000 μF |
| Movie | 1 nF – 100 μF |
| Tantalum | 1 μF – 100 μF |
Figuring out Capacitance Worth
To find out the capacitance worth of a capacitor, observe these steps:
- Set the multimeter to the capacitance measurement mode.
- Join the optimistic take a look at result in the optimistic terminal of the capacitor and the detrimental take a look at result in the detrimental terminal.
- Learn the capacitance worth displayed on the multimeter.
- If the capacitance worth may be very small or very massive, the multimeter might not be capable to measure it precisely. On this case, you should use an exterior capacitor tester.
- The capacitance worth of a capacitor is measured in farads (F). Nevertheless, capacitors usually have very small capacitance values, so they’re usually measured in microfarads (µF), nanofarads (nF), or picofarads (pF).
Capacitance Desk
| Capacitance Vary | Items |
|---|---|
| 1 – 999.99 µF | µF |
| 0.001 – 999.9 nF | nF |
| 0.001 – 999.9 pF | pF |
Discharging Capacitors Safely
Earlier than testing a capacitor with a multimeter, it’s essential to discharge it correctly to stop electrical shock. Listed here are the steps to discharge a capacitor safely:
1. Establish the Capacitor
Find the capacitor you want to discharge. It is going to often have a cylindrical or rectangular form with two terminals.
2. Collect Mandatory Supplies
You will want an insulated screwdriver, a pair of insulated pliers, and a discharge resistor (if obtainable).
3. Brief the Terminals
With the screwdriver or pliers, briefly contact the 2 terminals of the capacitor collectively. This may discharge the capacitor by way of the resistance of the instruments.
4. Test for Discharge
Utilizing a multimeter set to the voltage vary of the capacitor, join the probes to the terminals. If the voltage studying is close to zero, the capacitor is discharged.
5. Use a Discharge Resistor (Non-compulsory)
If a discharge resistor is obtainable, join it throughout the capacitor terminals for a couple of minutes earlier than shorting them. This supplies a extra managed discharge path.
6. Floor the Capacitor
Join a wire from one of many capacitor terminals to a grounded metallic floor, equivalent to a water pipe or {an electrical} outlet cowl plate.
7. Discharge By way of a Resistor
Join a resistor of acceptable wattage and resistance (usually 100 ohms or larger) throughout the capacitor terminals. Depart it linked for some time to make sure full discharge.
8. Double Test and Insulate
After discharging, wait a couple of minutes and re-check the voltage utilizing a multimeter. Cowl the terminals with insulating tape or caps to stop unintended contact.
| Capacitor Kind | Discharge Technique |
|---|---|
| Electrolytic | Brief terminals and wait (no resistor required) |
| Ceramic, Movie, Tantalum | Brief terminals utilizing screwdriver or pliers |
| Excessive-Voltage | Use discharge resistor and floor |
Capacitor Discharge
Earlier than testing a capacitor, it is essential to discharge it. At all times put on correct security gear and use a discharge device or a resistor to empty the saved vitality. Failure to discharge the capacitor may end up in electrical shock or injury to the multimeter.
Capacitance Measurement
Set the multimeter to the capacitance measurement vary, usually denoted by the “F” image. Join the optimistic result in the optimistic terminal of the capacitor and the detrimental result in the detrimental terminal. The multimeter will show the capacitance worth in farads (F).
ESR Measurement
Some multimeters can measure the equal sequence resistance (ESR) of a capacitor. ESR is a crucial parameter that impacts the capacitor’s efficiency and lifespan. Set the multimeter to the ESR measurement vary, join the probes to the capacitor terminals, and skim the displayed ESR worth.
Leakage Present Check
Join the capacitor in sequence with a high-value resistor (e.g., 1 MΩ) and a voltage supply. Measure the voltage throughout the resistor utilizing a multimeter set to the millivolt vary. The leakage present will be calculated utilizing Ohm’s legislation: I = V/R.
Polarity Test
For electrolytic capacitors, it is important to test the polarity earlier than testing. Join the optimistic lead of the multimeter to the optimistic terminal of the capacitor and the detrimental result in the detrimental terminal. If the polarity is wrong, the multimeter will show a detrimental capacitance worth.
Troubleshooting Capacitor Points
Open Capacitor
An open capacitor may have infinite resistance and nil capacitance. The multimeter will show “OL” or a really excessive resistance worth.
Shorted Capacitor
A shorted capacitor may have very low resistance and excessive capacitance. The multimeter will show a really low resistance worth or “0L”.
Capacitance Drift
Capacitance drift signifies a change within the capacitor’s capacitance worth over time. The multimeter can be utilized to watch capacitance adjustments underneath completely different circumstances (e.g., temperature, voltage).
Leakage Present Exceeds Specs
Extreme leakage present can result in capacitor failure. The multimeter can be utilized to measure leakage present and examine it to the producer’s specs.
Polarity Reversed
For electrolytic capacitors, reversing the polarity can injury the capacitor. The multimeter can be utilized to test the polarity and guarantee it’s right.
Deciphering Multimeter Readings
10. Measurement Scales
Multimeters supply varied measurement scales for capacitors, usually starting from nanofarads (nF) to microfarads (µF). Select the suitable scale primarily based on the capacitor’s anticipated capacitance. For instance, if testing a capacitor with a capacitance of 100 µF, choose the µF scale for correct readings.
| Capacitance Vary | Measurement Scale |
|---|---|
| 0.1 pF – 1 nF | pF |
| 1 nF – 1 µF | nF |
| 1 µF – 100 µF | µF |
How you can Use a Multimeter to Check a Capacitor
1. Set your multimeter to the capacitance vary.
2. Join the optimistic lead of the multimeter to at least one lead of the capacitor and the detrimental result in the opposite lead.
3. The multimeter will show the capacitance of the capacitor in farads (F).
4. If the capacitor is working correctly, the capacitance studying ought to be throughout the tolerance vary specified by the producer.
Folks Additionally Ask
How do I do know if my capacitor is dangerous?
There are just a few methods to inform if a capacitor is dangerous. A method is to make use of a multimeter to check the capacitance. If the capacitance studying is considerably decrease than the required worth, the capacitor could also be dangerous.
What’s the tolerance vary for a capacitor?
The tolerance vary for a capacitor is the vary of values that the capacitance can range from the required worth. The tolerance vary is often expressed as a share of the required worth.
