How do you test a capacitor?
2 Answers
Testing a capacitor can be done using a multimeter or a dedicated capacitor tester. Here are the steps for both methods:
### Using a Multimeter:
1. **Safety First**: Ensure the capacitor is discharged. You can do this by shorting the leads with a resistor (not directly with a wire) to avoid a spark.
2. **Set the Multimeter**: Turn the multimeter to the capacitance measurement mode (if available) or to the resistance (ohms) setting.
3. **Measure Capacitance**:
- For capacitance mode: Connect the multimeter leads to the capacitor terminals (red to positive, black to negative). Read the value; compare it to the rated value on the capacitor.
- For resistance mode: Connect the leads and note the reading. A good capacitor will initially show a low resistance (as it charges) and then move towards infinity (high resistance) as it charges fully.
4. **Check for Short or Open**: If the multimeter shows a reading of zero ohms, the capacitor is shorted. If it shows an open circuit (infinite resistance), the capacitor is likely failed.
### Using a Dedicated Capacitor Tester:
1. **Discharge the Capacitor**: Same as above, ensure the capacitor is fully discharged.
2. **Connect the Capacitor**: Follow the instructions for your tester, typically connecting the capacitor leads to the appropriate terminals.
3. **Take the Reading**: The tester will usually provide a direct reading of capacitance and may also indicate if the capacitor is in good condition.
### Notes:
- Always observe safety precautions when working with capacitors, especially high-voltage types, as they can hold charge and be hazardous.
- If the capacitor is polarized (like electrolytic capacitors), ensure you connect it correctly according to the polarity markings.
### Using a Multimeter:
1. **Safety First**: Ensure the capacitor is discharged. You can do this by shorting the leads with a resistor (not directly with a wire) to avoid a spark.
2. **Set the Multimeter**: Turn the multimeter to the capacitance measurement mode (if available) or to the resistance (ohms) setting.
3. **Measure Capacitance**:
- For capacitance mode: Connect the multimeter leads to the capacitor terminals (red to positive, black to negative). Read the value; compare it to the rated value on the capacitor.
- For resistance mode: Connect the leads and note the reading. A good capacitor will initially show a low resistance (as it charges) and then move towards infinity (high resistance) as it charges fully.
4. **Check for Short or Open**: If the multimeter shows a reading of zero ohms, the capacitor is shorted. If it shows an open circuit (infinite resistance), the capacitor is likely failed.
### Using a Dedicated Capacitor Tester:
1. **Discharge the Capacitor**: Same as above, ensure the capacitor is fully discharged.
2. **Connect the Capacitor**: Follow the instructions for your tester, typically connecting the capacitor leads to the appropriate terminals.
3. **Take the Reading**: The tester will usually provide a direct reading of capacitance and may also indicate if the capacitor is in good condition.
### Notes:
- Always observe safety precautions when working with capacitors, especially high-voltage types, as they can hold charge and be hazardous.
- If the capacitor is polarized (like electrolytic capacitors), ensure you connect it correctly according to the polarity markings.