A protection circuit suitable for use with electronic test equipment contains a switch which is open circuited if an overload condition is detected. The opening of the switch isolates the overload detector from the applied overload thereby allowing the detector to have a relatively low power handling capability. If the switch is manually closed whilst the overload condition persists the switch is automatically re-opened within a short predetermined time.
A control system for protecting a computer system against external fault conditions, including, in combination, circuits for monitoring and reacting to a plurality of power supply fault conditions, circuits for monitoring and reacting to a plurality of environmental fault conditions, circuits for monitoring and reacting to unauthorized access fault conditions, and circuits for driving off the supply of 3-phase power to the computer system in response to any one or more of these fault conditions. The invention also includes the various monitoring and reacting circuits in specific subcombinations.
