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Home > Protection Systems > Rack Protection Systems > Rack Protection System
Unit Function
The BiRa Rack Protection System (RPS) senses the environment in and around an electronics rack and turns off the rack’s AC power in the event of hazardous conditions. Examples of such are: DC Power Supplies out of tolerance, Loss or a decrease in rack cooling air, Excessive rack temperatures, Smoke, Water leaks or splashes, Loss or decrease of cooling water flow, Cooling water temperature increases, Excessive humidity, Door or Cabinet interlock switch breaches and AC Power loss in associated equipment. In the event that an out-of-tolerance condition does not pose an imminent threat, a WARN state is set; if the out-of-tolerance condition threatens the safety of the electronics, an ALARM state is set and the RPS turns off the rack’s AC power. (The RPS power remains on to enable it to continue monitoring environmental conditions.) In the event of a WARN state, an audible alarm sounds to alert personnel in the vicinity. The RPS also characterizes fault problems and stores descriptive data in a Latched Status Register that can be readout locally. After clearing a fault, an operator can reset the Latched Status register and turn off the audible alarm. An Ethernet link to control computers reports the Latched Fault Register state and enables remote fault state reset in the event that the problem has been cleared.
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General Description
The RPS system consists of the 8884 RPS Unit, an associated 8880-208/120 AC Relay Unit and rack environment sensors. The RPS Unit has interfaces for environment sensors, limit comparators, summing logic and the Latched Status Register. A jumpering patchboard in the RPS Unit enables selection of the parameters to be monitored. The rack’s AC power is provided by an AC Relay Unit. The RPS Unit powers relays in the AC Relay Unit and turns off the relays in the event of an ALARM condition.
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Applications
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The RPS system is especially-well suited for unattended applications such as Server Systems or Physics Experiments where equipment may be located in underground tunnels or areas that must be cleared during experiments. |
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Specifications Highlights
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The RPS can sense the outputs of 14 DC power supplies, rack cooling air inlet and outlet temperatures, inlet-outlet air temperature difference, inlet and outlet air flow rates, cooling air humidity, cooling water temperature and flow rate, and alarms from ionization smoke detectors. The user can change the DC voltage sensing limit thresholds by selecting comparator resistors. The Latched Status Register can be read out locally and the isolated contact outputs of 4PDT WARN and ALARM relays may be used to activate remote equipment. |
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AC power presence is sensed by a three-input AC Voltage Monitor PC board, typically located in an AC distribution box. Optical isolators on the board provide kilovolts of isolation between the board’s AC inputs and the logic state output to the RPS Unit. |
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Physical Data
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The 8884 RPS Unit is 1U (1.75 in) by 19 inches and is typically installed in the bottom of the rack to minimize cabling. The 8880-208/20 Relay Unit is 2U by 19 inches and is typically installed in the rack that it powers. |
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