What is the required resistance value in M ohms to discharge a 30 Mfd capacitor energized to 650V?

To determine the required resistance value for discharging a 30 microfarad (Mfd) capacitor that is charged to 650 volts, you can use the formula for the time constant ( \tau ) of an RC (resistor-capacitor) circuit, which is expressed as ( \tau = R \times C ). Here, ( R ) is the resistance in ohms, and ( C ) is the capacitance in farads.

In this case, to effectively discharge the capacitor, a commonly used guideline is to ensure that the resistance is sufficient to allow the voltage to fall to a safe level within a practical timeframe. The recommended resistance value for discharging capacitors is often derived using the equation:

[ R = \frac{V}{I} ]

For practical applications concerning safety, a standard voltage drop time is around 5 tau (5 time constants). Given that the capacitor value is 30 Mfd, which is ( 30 \times 10^{-6} ) F, if we choose a resistance of 10 M ohms, you can calculate the time constant:

[ R = 10 \times 10^6 , \text{ohms} ]

[ C =