Wait for the calculated discharge time based on the capacitor's specifications. Verify the voltage with a multimeter to ensure complete discharge. Using a Light Bulb: Connect a light bulb with appropriate power rating to the capacitor terminals. The bulb will glow as the capacitor discharges, and will go out when fully discharged.
Connecting a light bulb in series with the capacitor creates a discharge path. As the capacitor discharges, the bulb gradually dims until it goes out, indicating a complete discharge. This method provides a visual cue of the discharge process. Steps for discharging a capacitor using a light bulb :
Easiest and most reliable way to ensure capacitor discharge is to permanently connect resistors across the capacitor terminals. As soon as power source is turned off, capacitor starts to discharge through the resistor. Discharge resistor can be externally connected or mounted inside the capacitor can.
Select an appropriate discharge resistor based on capacitor voltage and capacitance. Connect the discharge resistor across the capacitor terminals using insulated probes. Monitor voltage decay using a high-impedance voltmeter in parallel with the resistor. Maintain the connection until voltage drops below 50V or to the specified safe level.
The Capacitor Discharging Graph is the a graph that shows how many time constants it takes for a capacitor to discharge to a given percentage of the applied voltage. A capacitor discharging graph really shows to what voltage a capacitor will discharge to after a given amount of time has elapsed.
Resistors are the preferred discharge device for capacitors though reactors and voltage transformers can also be used if faster discharge is necessary. By using resistor, the rate of discharge, resistor power dissipation can be controlled to a high degree by the designer.