Hot insertion power arrangement

A system comprising:

• a first power bus for conducting a reference potential;
• a second power bus for conducting a primary power supply voltage;
• a third power bus for conducting an advance power supply voltage;
• a first power source providing said reference potential and a first voltage, said reference potential being coupled to said first power bus, said first voltage being coupled directly to said third power bus, said first voltage being coupled to said second power bus through a first non-linear device,
• said first non-linear device allowing current to flow between said first power source and said second power bus in only a first direction, said first non-linear device having a first voltage drop across said first non-linear device when a first current flows through said first non-linear device in said first direction;
• a first plug-in module having a first module pin for connection to a first power bus pin connected to said first power bus, a second module pin for connection to a second power bus pin connected to said second power bus, and a third module pin for connection to a third power bus pin connected to said third power bus,
• a load in said first plug-in module being coupled to said third module pin through a second non-linear device, said second non-linear device allowing current to flow between said third power bus and said load in only said first direction, said second non-linear device having a second voltage drop across said second non-linear device when said first current flows through said second non-linear device in said first direction, said second voltage drop being of greater magnitude than said first voltage drop, said load being connected directly to said second module pin,
• said first module pin, said second module pin, said third module pin, said first power bus pin, said second power bus pin, and said third power bus pin being configured such that when said first plug-in module is inserted for electrical connection to said first power bus, said second power bus, and said third power bus, said third power bus pin makes electrical contact with said third module pin before said second power bus pin makes electrical contact with said second module pin, and said first power bus pin makes electrical contact with said first module pin before said second power bus pin makes electrical contact with said second module pin,
• whereby an initial connection of said reference potential and said advance power supply voltage to said load in said first plug-in module, before a connection of said primary power supply voltage to said load, enables said load to be placed in a substantially quiescent state prior to connection to said primary power supply voltage.