What size resistor do I need to discharge a capacitor?

A resistor rated to dissipate the amount of thermal energy created when discharging the capacitor. Minimum requirements for resistor is 2k OHM 5w for small capacitors, 20k OHM 5w for large electrolytic capacitors used in power supplies, electric motor start circuits and camera flash circuitry.

How many ohms does it take to discharge a capacitor?

A 10,000 ohm or larger will work fine, the bigger it is the faster it will discharge.

How do you calculate the discharge of a capacitor?

Mathematical treatment of charging and discharging a capacitor

1. Capacitor discharge (voltage decay): V = Voe-(t/RC)
2. Capacitor discharge (charge decay): Q = Qoe-(t/RC)
3. V = Voe-(t/RC) and also I = Ioe-(t/RC) Q = Qoe-(t/RC)
4. Capacitor charging (potential difference): V = Vo[1-e-(t/RC)]

How do you choose a bleeder resistor?

To select a suitable bleeder resistor, you can consider the relationship between the momentary voltage across the capacitor Vt, the bleeder resistance R for discharge, the initial voltage Vu. t is the momentary period and the total capacitor capacitance is C.

Why discharge resistors are needed?

Power capacitors store electrical charges that after their disconnection can turn out to be dangerous for people during operation of inspection and maintenance. To reduce these voltages to safe values, discharge resistors must be used.

How capacitor is discharged using multimeter?

Open all switches on the power board. Then bring up the voltage supply on the capacitor to 100V with all switched adequately opened. When the voltage reached 100V, turn off the charging switch of the device. Wait for a few moments until the digital multimeter (DMM) display shows the result strictly at 100V.

How do you calculate the bleeder resistor?

The resistor value is calculated by putting the capacitance, initial voltage, safe voltage and discharge time in the first formula. Then put the value of initial voltage and the resistor value in second formula to get the power consumption.

What is capacitor discharge current?

Discharging a capacitor means releasing the charge stored within the capacitor. Let’s go over an example where a capacitor is discharged. We connect a charged capacitor of capacitance C farad in series with a resistor of resistance R ohms.

How do you discharge a capacitor on a power supply?

Hit the power button on the computer a few times. This will drain the capacitors for you. The fans will spin briefly at the first power button push. I usually push it four or five times to make sure the capacitors are completely drained.

What is the value of bleeder resistor?

In the circuit above let us take capacitance of C1 is 4µF, the initial voltage is Vo is 1500V and the safe voltage Vsafe is 10V. If the discharge time we want is 4 seconds then the bleeder resistor value should be 997877.5 ohms or below than that. You can use a near valued resistor to this value.

What is bleeder resistor why resistance used with capacitor?

In electronics, a bleeder resistor is a resistor connected in parallel with the output of a high-voltage power supply circuit for the purpose of discharging the electric charge stored in the power supply’s filter capacitors when the equipment is turned off, for safety reasons.