Using the Power Supply's EPOW Signal To Capture And Log Non-Disruptive Power Line Disturbances
Original Publication Date: 2000-Apr-01
Included in the Prior Art Database: 2003-Jun-18
The power subsystem of a Netfinity server is typically equipped with an EPOW (emergency power off warning) signal line. The purpose of this line is to warn the system that AC power has dropped below its normal voltage range. This allows the system to shut down in an orderly fashion and not risk data integrity or unpredictable behavior if DC power is lost. The system may or may not shut when the EPOW line is triggered by low AC voltage. This depends on factors such as how low the AC voltage dips, how long the AC voltage is below normal, and the DC load at the time of the AC voltage drop. This is because the power subsystem monitors the DC voltages to determine when to shut down the system. If any of the DC voltages drop below their specified levels, the power subsystem will shut down. Here is the sequence of events that would take place if AC power is lost long enough for the system to shut down: 1. AC power drops below the normal voltage range. 2. The power subsystem triggers the EPOW line. All DC voltages are still within specification.