SFVC-D

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Elect'onic volume converter for Eas meters

Instal lat ionCommissioning OperationMaintenance

1. General---

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Metrologicalcompartment

Programming switch=

SEVC-DCobsr p[.5 n,,

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EEx ra tlc T4 f, L C.t E. no 95

Bqltery compartment

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1.1 !'troductionThe SEVC-D belongs io the new generat ion of volume

"ortt"o wnich iJcharacierisecj by its self-contained

;"; supply, s imple'operat ion and compactness' To.ni.u" a nlg tevet of performance, it was designed usingthe latest electronic technologtes :

. gurface-mounted cornDonense i f es.si sGi isi i ;s ing t l re FSCI iFcl ' r ' Si ! ic tn Ori

Insulator) technoiogYDue to the high performance of i ts sensors and

"""tto"t, the SEVC-D has been approved to be used for

commercial g as transactons.

This appr 'cval \ ,vas achieved in compl iance with thecunient (draf t standard) issued by the EuropeanWorking Group on electronic gas volume converslonnstruments.

1.2 Operatng PrinciPleThe gas meters measure a volume. (Vt)tnder specif icpr. . i r tu and temperature condi t ions' This volume is[oue into a volume under basic conditions (Vb)'

:, ' ,, , ""'! Vcjtume measured at metering conditions= Converted volume to reference conditions= Absolute gas temperature at metering conoitions= Reference temperature (273.15 K or 288'15 K

in most cases)= Absolute gas Pressure ln bar- Absolute reference pressure (1 01325 bar)= Gas compressibility factor at metering conditions= Gas compressibility factor at reference conditions= Conversion tactor

The SEVC-D f i rst computes volume V* f rom the totalnumber of pulses dur ing the correspon'dlng per lod'.uttipti.a by the reference pulse weight lt then achievestne conversibn under basic condrtions to compute Vb'

'f.3 tlescriPtionThe SEVC-D is contaired iri a tigirt Poit'"tttot'*'t aseTlTe.casing,is,wall-rnounted and comprised two parts ;

A MetrologiealPartThe cover which acconnmodates the main board, iheo!spiay, the k.eirboard, the pt ieal l in l i ar ld ' . f ieconnectiens tc ihe L.ow Frequeneio srgnal' nronit*rlngnput, oressure sensor and ternperature probe.The proiections against electromagnetc interferenceand the programming switch are also included in thispan.

B Custonner PartThe battery compartment which contains the connectingboard with terminals. the retransmission outputs ' theserial links, the on / off inputs, and the connection for aoptional external Power suPPlY.

The connect ing board also includes an alarm resett ingpushbutton and hardware configuration switch'

In addition to the above case' the SEVC-D is suppliedwith:. a pressure sensor with a 2.50 m cable,

. a temperature probe with a 2 50 m cable'

. an external intr insic safety power supply module'available in option,

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1.4. Typical configuration

I{AZAFDOUS ZONE SAFE ZONE

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1. General

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1.5 Main functionsThe SEVC-D provides the following functions :

. acguisition and integration ol the volume measured'bythe meter,

r gs temperature and pressure measurement'. calculation of the compressibility factor in accordance

with the selected calculation formula'. calculation of the conversion factor,. updating of the various volumes'. calculation of the measured and converted flow rate'. dispfay of information,. management of alarm$. managmqnt of the data base (consumption, pressure'

temperature) at programmable recording intervals,. communication with a terminal, via the serial or optical link,. LF pulse retransmission of measured volume,

converted volume and alarms.

1 .6 Technical characteristics1.6.1 Metering input

The metering input is designed for connection with theoutput of a Low Frequency pulse transmitter, of the drycontact type (Reed contact, for instance)'Maximum frequency of the anti-bouncing tilter : 2Hz.t

, f*seweight programmable among values:0,01 ;0 '1 : 1 ;10 mr per pulse.

1.6.2 Temperature Probe. PT '1000 type thermistor (1000 O at 273.15 K). Typical precision :0.1% of the measurement.. Construct ion : stanless tube, 6 mm outer diameter

probe crimPed on the cable.. Cable : 6 mm diameter, 2 conductors with shield: 2 5 m

tong

1.6.3 Pressue sensorThe absolute pressure sensor was especially designed bySchlumberger Gas for this application and s the mostimportant element of the SEVC-D in terms of accuracy andperennity. A temperature compensation of the pressuremeasurments is bult into the sensor, thus mantaining theperformance whatever the temperature.. Sensor wth strain gauge.. Aflowable transient overpressure : 150% of Pmax.r Breaking pressure : 300 % of Pmax.. Typical precision : t 0.3 % of the measurement Metrological rangeability : 5.r 4 absolute pressure ranges are available :

- 0.9 to 4.5 bar-2to10bar-4to20bar-

15 to 75 bar.. Cable : 8 mm diameter, 6 conductors with shield. 2.5 m

long.. Pressure tapping : l/4" male gas connector.

1.6.4. Monitoring input

This input may detect :

- breaking or faul ty connect ion of the Low Frequencycable since it is shorted on the meter connector,

- magnet ic v io lat ion of a meter f i t ted wi th an ant i -tamfer ing Reed contact ; th is contact is Normal lyclosed and opens upon detection of a magnetic fieldwhich is sufficiently high to disturb correct operation ofthe metering Reed contact.

1.6.5. On / Off inputs. Can be connected to any dry contact of an approved

intrinsic safety instrument.. Scanning every 20 seconds.. Possible operation in Normally Open r'Normally Closed

logic. Alarm display upon status change. Maximum length : 10 m

1.6.6. Accuracy

Conversion coefficient preciston :

. metrological compl iance ( future European standardelaborated by TC 2371WG4, in which Schlumbergernarf i ineioc]Pe ( 'vPqrsv,

- better than 0.5 % of the measurement at 20'C- better than 1 % of the measurement for an ambient

temoerature, between -20"C and +50'C'

typical accuracy :- better than 0.3 9 of the measurement at 20'C- better than 0.5 % of the measurement for an ambient

temDerature between -20"C and +50'C.

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1. Gemerat--

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- Absohte gas pressure (bar)- Gas tenlnerture {in "0i. Ccr':"1:re ssibility alrr,, ;atic iLZo)- Conversion coefficient-

Alarm codes (Ll-l side code for current alarms, RHside codes for alarms slored in memory)

n 3 symbols on the display corrbsponding io :- Presence of.4n alarm- Battery low- Flowrate other than zero.

1.6.8 Power supply

By main battery:. Specif ic power supply unit , consist ing of a Li thiumbattery and the protections required by intrinsic safety

rules.The battery unit can be replaced in Hazardous Zones.

. Typical operating life : 5 years.

By external power supply:t An extBrnal module which converts an external power

,s_yeel&frg a 6Vointrinsic safety power suppiy (e.g. :Intnnsic safety power supply module by Georgrn. motelAV B 131). In this configuration, the main battery is replaced by a

small backup battery which majntains integrai operatronof the SEVC-D during g0 days in case th marn powersupply fails.

t.6.9. OutpL4tsRetransmissions of the unconverted and convertedvolume pulses : optocoupler-isolated outputs.Retransmisson of a current alarm : contact c losing incase of alarm.Optical l ink for confgurat ion and remote-readrng wrrhnon permanent connection.l : f i ] , l I for conf igurar ion and remote_readrng wrrhoermanent connect ion.

1.6.1A. Data base* Cycfic recording of the rnain data n a a0 Kb EEpROfd.

O Storage of data during ntervals ; the ouration of thenterval is programmable: 15 mn,60 mnor 24h.These data are stored durino :--40 days for t lre iS mn interal- i46 da;,s for tfe l'curlv inrervaj.- I years for the daily interval.For each interval , ihe fo lowing data are stored inmemory:- rne unconverted volume durrng the interval,

' - the converted volume during te interval,- the average temperature of the interval.- the average pressure of the interval.- Backup time & date

O Storage in memory of the last 200 evets with the daleand time of occurrence.

' fhese events are :- temperature alarm.-

pressure aiarm,- f low rate alarm- battery alarm,- onlof,f input status change,- monttoflng input status change,- external power supply cut.- date and time change,- recording tir ire change,- alarm reset, volumes under aiarm reset.- database reset,- SEVC-D reset

O For each of the last 14 months, storage in the memorv ofthe :- unconverted tndex at the end of the rnonth.- converted index at the end of the rnonth.- unconverted index dur ing metrological a larm at the

end of the month.- maxmum unconvened volume of an interval.detected

in the month wi th i ts date and t ime, average T and p,- maxtmum converted volume of an interval detected in

the month wtl-l i ts date and time, average T and p

O For ihe current and previous days, storage in thememory o :- maxtmum converted volume of an interval detected in

the last oay wi th i rs relat ive date. t ime, correspondrngunconver ied volume, average temperature andaverage pressure

O F' ; r the current ano previous months. storaoe In thememory ot- ' .naxrmum ccnverted volume of an interval c ietecled in

: te lasl monfh ,vr th i rs reiat ive date. t me.: : ; ' resoondini ; r lnconvertecj voiume averaqe:: . rncer3ture and J\ , ,eraoe oressure.

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