IEEE Transactions on Nuclear Science, Vol. 33, No. 1, February 1986

FASTBUS RACK' ALARMS AND LIMITS

Merle HaldemanFermi National Accelerator Laboratory, P. O. Box 500, Batavia, IL 60510*

Sergio ZimmermanFermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510*

Instituto de Fisica da Universidade Federaldo Rio Grande do Sutl, Porto Rlegre, 90000, Brazil+

ABSTRACT

A FASTBUS based data acqLuisition systemis under constructior-n at the Fermi NationalAcceler.ator Laboratory for the ColliderDetector at FERMILASB (CDF). This system islikely to have in the ar-ea 35 to 40 racks,25 of which may houise up to 3, FASTBUS crates,associated power supplies and coolingaparatus. Such a rack may represent as muchas $175,000. Th is paper describes a rackprotection system, designed to gr-eatelyreduce the possibility of large scale systemdamage, which will add an additional cost ofapprox-.imately i to 2 %.

INTRODUCTION

The data aqUi si t i orn system of theCollider Detector at FERMILAB will consist ofabout 25, 36 inch deep rackh:s with at most, 3FASTBUS crates per rack. The crates arestacked vertically (see figLre 1,) withair/water heat exchangers below each crate toprechill the cooling air before entering thecrate. A blower at the bottom of the racl:k:circulates the cooling air through thecrates, each of whic h may dissipate up to2500 watts. An additional air/water heatexchanger is installed above the uppermostcrate to prechill the air for the remainderof the equipment in the rack.. Each crate iscapable of housing up to 26, single width,FASTBUS modules. A three crate system maythus have as many as 78, single width,FASTBUS modules witth an estifnated value of$175 000-: thuts the need for some means ofequipmentl protection. This document describesa system ramed the "FASTBUS Rack: Alarms andLimits System" (FRALS) which provides thisprotecti orn.

SYSTEM OVERVIEW

FRALSwi th theequipmentdestructiveboth humanCDF dateessential ly1.

is beirig designed and constructedbasic philosophy of minimizing

damage during potentiallyfailures, as well as maximizingsafety and the reliability of the

acquisition system. FRALSi consists of two subsystems:

The stand alone portion is named the "RackProtection System". This system residescompletely in the FASTBUS racik and isindependent of any external hardware or

software for rack protection and localwarning.

*

Operated by Universities ResearchA5ssociation for the Department of Energy.

Work partially supported by CNPq.

2. A connection to a distributed CAMAC systemnamed the "CAMAC System" which has theresponsibility of adding intelligence toFR:ALS.

RACK PROTECTION SYSTEM

The Rack F'rotection System is a standalone, AC powered (with partial batterybackup) system which has the associatedelectronics located in the 3-1/2 inch highchassis. This chassis is located in theuppermost 5-1/4 inch portion of the FASTBUSrack: .

The warning and protection capability isbased on information received from manysensors within the rack. The information fromthe sensors is compared with preset limitsand, depending on which limit is ex8ceeded,issue a warrirg or activate the protectionmechanism. The parameters monitored by thesensors are the following:

1. power suApply voltage and current2. chilled water temperaturesc.chilled water flow

4. cooling air temperature5. cooling air flow6. chilled water leak or condensation7. chilled water pressureS. cooling air humidity9. smoke10.position of the rack rear door11.safety ground current

The circuitry connected to these sensorsis essentially repeated for most of them. Theincoming sensor signal is buffered, amplitutdeadjusted and in some cases, signalconditioned. It is then sent to the frontpanel test jacks, to the CAMAC system and toa comparator. The input which is sent to thecomparator, is compared with a referencevoltage to determine tthe limit. The outputof the compar-ator drives a latch which inturrn drives the front panel statusindicators. This latch is battery poweredduring the abserce of AC. Some of the latchesprovide only warning and others both warningand control for rack protection. This standalone protection is not dependant on hardwareor software outside the rack and is designedsuch that the most likely modes of failurewill not inhibit rack protection.

The battery is sized to operate RAPS forabout one day without recharging. In normaluse, the storage battery charger is supplyinga current su+ficient to supply RAPS plustrickle charge the battery.

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FRONT VIEW

Inlet air filterAccess FPanelPower stripAir/Water heat exchangerFASTBUS crateRack FProtection ChassisBlower

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LEFT SIDE VIEWREAR DOOR OPEN

Air duct-2 volt power SLtpply+5 volt power supply-5.2 volt. power supplyRack rear doorChilled water manifoldChilled water hoses

FIG. I

CDF Data Acquisition, FASTSUS Rackh Configuration

The 5-1/4 inch front panel on the RackProtection Chassis at the top of the rackprovides test jacks and status indicators.The status indicators show the current rackstatus dUri ng normal operatioon or, in theevent of a system shutdown, the cause ofshutdown. The test jacks allow the user tomeasure the present DC output of each sensorwith a digital volt meter.

Each status indicator consists of twolight emitting diodes (LEDs), red and yellow,one of which is always energized. If AC poweris removed, status indicator power is removedto conserve the battery, except for onespecial indicator. This indicator representsthe logical OR of all the others. The totalrack status can still be determined bydepres5sing a front panel push button. The

color of these indicators have the followingmeaning: yellow indicates the sensedparameter is within the limits specified, redthe opposite.

The protection mechanism of the systemrelies on control of four different devices.They are:

1. The rackh main AC power circuit breaker2. Halon gas valve.3. The chilled water flow valves (inlet

and outlet).4. The air mover.

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The parameters moriitored by the RackProtection System which triggers theprotection devices are the following:

1. water leak-age. cool i rng air, over temperatLure

3. (C power over-load (greater than 60amperes, 3.: phase, 2(1-)8 volts).

4. smoke5. excessive electrical qroLrid cuLrrent6. air flow (optiornal via circuit board,

soldered irn jumper wire)

The Rack: F'rotection System also providesa meanrs for the CAMAC system to control theair mover and the chilled water valves forthe purpose of certifying device irntegrity.

CAMAIC SYSTEM

Irn parallel with the hardwired RackProtection System is the CAMAC system. As wasstated in the introduction, the CAMAC systemis to provide some intelligence to FRALS inthe following forms:

VarioUs types of failu res inside therack coCUld be ver-y expensive, both in timeand money. Taking immediate protective actioncan greately minimise both, however th isrequires proper fLunctioning of the sensingand controlling devices. The integrity ofwhich can be periodically determined bypertturbing the system and monitoring theresponse. The CAMAC system will,for example,have to have the ability to turn the chilledwater to the rack off and look for an

appropriate response from the water flow,e hauLt water temperattre, air temperatLtreand water pLessSUre sensors.

CONCLUSION

Although this system is not yetcompletely constrLucted, many portions havebeen assembled and tested satisfactorily. Itis anticipated that the first Lunit will beassembled soffietime in December.

1. a statuS sheet for each rack providinginformation about the assorted sensorswithin the associated rack..

2. long term recor-ds or plots illustratinggradually changing trendis e.g., gradutallydimin-ishing air flow or water flow orpossibly gr adual l y increasing grouLndci fauLltcLurrent.

.3. verifyinrg zxutomatically, the integr ity ofseveral o0f the devices by pertutr-bing thesystem and monitoring the sensor response.

4. providing limited user interactivediagnostic capability.

To do so, this system will acceptsignals f rom the various sensors via theCAMAC OUtpUts of the Rack 'Protection System.These sensor signals are connected to a CAMACscanning AI/D converter and, with the use of aCAMAC 1 Ocal intelligent aLk' i1 i ary cratecontrol ler, determine that the signals arewithin or beyond pr eset limits.

In general , a user will be able to go toa ter-minal and via several menus make a widevariety of choices. From a main menu, theuser- should be able to select major detectorsystems eq. FRALS. Selecting FRALS on themain menu shoul d cause the next menu toappear which will give the user the followingchoices:

1. a parameter status menLt which allows theuser to select an individLal rack forwhich the complete parameter Statuts willbe displayed.

2. a control menu which allows a user toselect a particular rack and controldevices in it.

3. plot menut whiich provides a menu with a

list of plotted devices in the selectedrack. Selecting a device provides the user

with a plot of the sensor output versus

time.4. a diagnostics menu which allows a user to

single out as many as eight individualsensors which can be monitored andplotted.