Elster Instromet 2000, Instruction Manual

Page: 44 / 136

Model 2000 Flow Computer Instruction Manual
2.0 GENERAL DESCRIPTION
Model 2000 issue 21 Page No
37
2.4.7.2. ALARM OPERATION
If either the gas data value is in an accountable alarm condition i.e. outside the Max./Min. limits or a connected gas
chromatograph is in an accountable alarm condition (See Alarm Information.) then the used value can be selected from a
number of sources:-
Use Keypad
Use Last Good Value
Use Chromat
Use Modbus
Use Analogue
Use Hourly Average
Use Daily Average
Use Keypad will select the preset or keypad value.
Use Last Good Value will use the last good (non alarm condition) value.
Use Chromat will select the value from a chromatograph if available.
Use Modbus will select the value from a serial input if available.
Use Analogue will select the value from an analogue input if available.
Use Hourly Average uses current hourly average
Use Daily Average uses current daily average
If no LGV is available for example none has been written or read from a gas chromatograph then the Model 2000 will
always default to the Keypad value.
2.4.7.3. GAS CHROMATOGRAPH INPUT
The Model 2000 can be set to operate with a Gas Chromatograph input for Gas Data, See paragraph 2.4.7 for details of Gas
data inputs and page 75 for details of Gas Chromatograph types that are supported. The following parameters will need to
be set up to support the Gas Chromatograph Input:-
Chromatograph Type Selected from list
Chromatograph Comms id Must match ID in the GC
Chromat Status Status alarm indicated or ignored
Chromat read time interval Set to selected Intervals 1min to 1 hour
or continuous
C6+ code Gas component code used for C6+
% hexane to % decane in C6+ result.
Certain specific Gas Chromatographs (See page 75) will also require the following parameters to be set:-
Gas Component Max. and Min. Scaling factors.
Full Scale factors.
Gas Component Addresses.
The communication port used for the gas chromatograph input be configured to be the same as the communication
port on the gas chromatograph and the port function set for gas chromatograph input. See paragraph 2.9.
2.4.7.4. ANALOGUE TRANSMITTER INPUTS FOR GAS DATA
The Model 2000 can accept current input signals for Superior Heating Value Hs, Inferior Heating Value Hi, Relative density
rd, Molar % CO2, Molar % N2 and Molar % H2 which are fed into an single sided amplifier and having a response time of
approximately 470ms.
Input current: 4mA. to 20mA.
Input resistance: 100
Ω
To interface with the hazardous area where intrinsically safe transmitters are used a safety barrier must be used.
2.4.7.5. HEATING VALUE UNITS
The Model 2000 can be set to operate with a Heating value Units as follows, these Units apply to both Superior and Inferior
Heating Values. Unit changes will also apply to the Energy Totals and the Energy flow rates. When an Energy Unit is
selected it is assumed by the Model 2000 that any values received for Heating Value will be in the selected Units.:-
MJ/m3
kWh/m3
kcal/m3
thrm/m3 (Therms i.e. 1000*kcal)
BTU