What hazard exists in a power supply immediately after turning it off?

After turning off a power supply, one of the primary hazards present is the charge stored in filter capacitors. When power is removed from a power supply, capacitors can hold a significant amount of electrical charge for a period of time. This stored charge can create a dangerous situation if someone inadvertently comes into contact with the terminals of the capacitor, as it can discharge unexpectedly and deliver a potentially harmful electrical shock.

Filter capacitors are designed to smooth out the voltage output from a power supply, and they are typically charged to high voltage levels. It's essential for anyone working with these devices to properly discharge capacitors before beginning work on the circuit to prevent injury.

While circulating currents in the DC filter, leakage flux in the power transformer, and voltage transients can be relevant under different conditions, the immediate concern after shutting off the power supply is the presence of stored charge in filter capacitors. Proper safety protocols, such as waiting for a discharge period and using appropriate safety equipment, are measures that should be taken to mitigate these risks.