Capacitors are found in many electrical devices and parts of electronic equipment. They store excess electricity when there is an overvoltage, and discharge it when the voltage is lower, in order to guarantee constant electricity to the device. The larger the capacitor, the more charge it can store, even after the device is turned off. Before working on an electronic device or appliance, it is necessary to discharge its capacitor. This article outlines the steps to safely discharge a capacitor.
Steps
Step 1. Learn and use proper work techniques and equipment to work on electrical equipment
Don't touch anything with your bare hands.
Step 2. Disconnect the device with the capacitor from the power supply
The electric current will flow through the capacitor until you remove the power supply. This current intensifies the shock you can get from mishandling the capacitor, and also can continue to charge it.
Step 3. Look for the capacitor
Most capacitors consist of two conductive walls separated by an insulating layer; More complex capacitors have several layers of metallized plastic. Large capacitors, the most dangerous ones, are cylindrical in shape and resemble a battery.
Step 4. Disconnect the capacitor from the system if it is not permanently installed
This can avoid damage to the circuit when discharging.
If you can remove it, it is probably a large capacitor, and therefore potentially dangerous
Step 5. Connect, for several seconds, a device to the capacitor terminals
In this way the electricity will have a way out, and the capacitor will discharge. You can use a 5-10 Watt resistor, voltmeter, or light bulb.
If you use a voltmeter or a light bulb, you can check the progress of the discharge by monitoring the voltmeter display or the intensity of the light bulb
Advice
- Once the capacitor has discharged, keep its terminals connected with a resistor or electrical wire, in order to keep it discharged.
- Do not lick your fingers, with the intention of discharging the capacitor by touching one of the terminals! You could be electrocuted!
- Capacitors discharge themselves over time, and most, if not powered by an external source or internal battery, discharge within a few days. However, it is recommended to assume that they are charged until you are certain that they have discharged. The device must not simply be turned off, but disconnected from the power supply.
- Do not hold the resistor in your hand, but use a test lead or electrical wire.
Warnings
- Although it is possible to use a small screwdriver to connect the terminals of a capacitor, the amount of current discharged could melt its tip or, if still connected, the copper of the electronic board. Large enough sparks can burn the power supply or melt the copper and turn it into a bullet that could injure you.
- Large capacitors are extremely dangerous, and often other capacitors can be in the vicinity of the one you need to work on. Handling them is probably not the best solution for a hobbyist.
