Mains on delay circuit

The delay is intended to switch on the mains to heavy loads gradually to ensure that the switch-on current remains within certain Iimits and to prevent the fuses from blowing. The elements that cause high currents ar switch-on are, for instance, the electrolytic capacitors in the power supply of an output amplifier. Since these are not charged at switch-on, they constitute a virtual short-circuit on the supply lines.