Elster Instromet 2000 - Analogue Transmitter Pressure and Temperature Inputs; PRT Temperature Input; Pressure & Temperature Sensor Scaling

Model 2000 Flow Computer Instruction Manual
2.0 GENERAL DESCRIPTION
Model 2000 issue 21 Page No
34
2.4.5.4. ANALOGUE TRANSMITTER PRESSURE AND TEMPERATURE INPUTS
As an alternative to the HART transmitter inputs described in paragraph 2.5.4.3 the Model 2000 can also accept current input
signals for Pressure and Temperature which are fed into an single sided amplifier and having a response time of
approximately 470ms.
Input current: 4mA. to 20mA.
Input resistance: 100Ω
To interface with the hazardous area where intrinsically safe transmitters are used a safety barrier must be used.
2.4.5.5. PRT TEMPERATURE INPUT
The Model 2000 may also be configured to accept a platinum resistance thermometer (PRT) with a nominal resistance of
100Ω at 0°C and operating range of -20°C to 100°C. PRT linearization is performed by the Model 2000 automatically. The
PRT is energised at 3.5mA. with a constant current source and is connected to the Model 2000 in a 3 wire configuration
compensating for line resistance changes due to ambient temperature changes. As an alternative a PRT input board may be
fitted on this board there are two PRT input stages which can be used in the 4 wire configuration.
2.4.5.6. PRESSURE & TEMPERATURE SENSOR SCALING
The Model 2000 can also be configured so that each of the connected Pressure or Temperature Sensors can be scaled
using a simple equation as follows:-
)TxP1.R(1.OffsetScaleP
11
×+=
Where
P1 Scale : Pressure P1Scale is the value passed to the multiple transmitter selection process.
(See paragraph 2.5.5).
R.1 : Pressure P1 Range Scaling Factor
Offset.1 : Pressure P1 Offset Scaling Factor
P1 Tx : Pressure P1 Actual measured
Identical Equations also apply for all Pressure and Temperature Sensor inputs.
2.4.5.7. AVERAGE PRESSURE, TEMPERATURE & DENSITY
The Model 2000 calculates and makes available four averages for the used pressure and temperature values, these are as
follows;-
Flow weighted Last Hour Average
Flow weighted Last Day Average (Contract time to Contract Time)
Time Last Hour Average
Time Last Day Average (Contract time to Contract Time)
For machines that use density there are four averages available. These are as follows:-
Time Last Hour Average,
Time Last Day Average,
Rolling Hourly Average,
Rolling Daily Average.
All average values are available to be displayed, printed etc. no set up is required they are calculated automatically.