IBM System/7 Functional Characteristics - All about the IBM 1130 ...

Power Failure and Thermal WarningPower FailureThe power failure detect feature in the System/7 presents a warning of possible powerfailure due to low voltage or loss of primary voltage in a 5026 Enclosure. Input powerfalling below 85 percent of nominal voltage actuates the power failure detection circuit.This circuit signals the processor that an imminent power shutdown in the enclosure ispossible. The signal remains in effect for the duration of the low-voltage condition.If the master unit loses power, the entire system shuts down; if a remote unit losespower, only the remote unit shuts down.With this feature, power can be automatically restored to the enclosure that sustainedthe power loss if the automatic restart switch on the operator console is turned on. Whenthe switch is set in the on position and a power failure occurs, the modules in the enclosureare automatically reset when power is restored. If the failure occurs in a master unit, anautomatic IPL takes place if the operator console and IPL device are properly set up. Ifthe power failure and automatic restart occurs in a remote unit, no IPL takes place inthe master unit.Even though the power failure detect feature is installed on an enclosure, power is notautomatically restored if the automatic restart switch is set in the off position. In thatposition, an operator must manually set the power switch to the off position and thenback to the on position in order to restore power to the enclosure.The power failure detection circuit signals the processor of an imminent power shutdownregardless of the setting of the automatic switch.Thermal WarningThe System/7 operates in a temperature range from 40°F to 122°F (4.4°C to 50°C). Fordetails on the temperature range for individual units, refer to the publication IBM System/7Installation Manual—Physical Planning, Order No. GA34-0004. System/7 temperaturesensing circuits are provided to remove power from the enclosure to prevent damageto the system in an over-temperature environment. Prior to shutting down the powersystem, the sensing circuits alert the processor that an imminent power shutdown ispossible. The over-temperature condition is also indicated by the thermal light on theoperator console.Power can be restored when the thermal light goes off by turning the power switch tooff and then to on. If the thermal condition that caused the power shutdown persists, acustomer engineer must be called.Introduction 1-7