FIELD MOUNTED
RATE TOTALISER
MODEL 202A
2 August 1999
CONTENTS
1. Introduction 3
1.1 Model Number Designation 4
1.2 Operation 6
1.3 Intrinsic Safety Considerations 7
2. Specification 8
3. Programming 10
3.1 Program Steps 11
3.2 Calculation of Rate and Total 14
3.3 Total Conversion 16
3.4 Filtering 17
3.5 Example 19
4. Signal Input 20
5. Alarm & Pulse Outputs 21
6. Intrinsic Safety Connections 23
7. Installation 25
7.1 Wall Mounting 25
7.2 Panel Mount Version 26
7.3 Removing the Front Panel 27
7.4 The Main Electronics 29
7.5 Wiring 30
7.6 Terminal Designations 31
Index 32
Introduction 3
1. INTRODUCTION
The Model 202A Rate-Totaliser is a microprocessor based instrument designed to
measure a 4-20mA signal from flowmeters and pressure transducers. The
instrument can be programmed to display directly in engineering units and
includes features such as linear or square law calculation, integration and digital
filtering.
Rate, Total and Accumulated Total can be displayed in engineering units on the
large LCD display. A front panel switch selects the function for display and a
Reset button allows the Total to be reset to zero.
The instrument is fully programmable, with all calculation constants set via the
front panel switches and stored in a non-volatile memory which will retain data
indefinitely. The user can program span, filtering levels, display resolution and
cutoff point.
The instrument is powered from a 4-20mA input signal and therefore, requires
no external power.
This instrument conforms to the EMC-Directive of the Council of European
Communities 89/336/EEC and the following standards:
Generic Emission Standard EN 50081-1 Residential, Commercial & Light
Industry Environment.
Generic Emission Standard EN 50081-2 Industrial Environment.
Generic Immunity Standard EN 50082-1 Residential, Commercial & Light
Industry Environment.
Generic Immunity Standard EN 50082-2 Industrial Environment.
In order to comply with these standards, the wiring instructions in Section 7.5
must be followed.
4 Introduction
1.1 MODEL NUMBER DESIGNATION
The Model Number of an instrument describes which input and output options
are installed.
Model 202 A. 1 0
Input Options
A for 4-20mA no options available at this
time
Mounting
1 for panel mounting
2 for field mounting
6 for pipe mounting
Introduction 5
The Model 202A
6 Introduction
1.2 OPERATION
The Model 202A Rate Totaliser will display:
Rate
Resettable Total
Accumulated Total.
Both the Rate and Resettable Total are continuously displayed while the
Accumulated Total is only displayed when the ACCUM TOTAL key is pressed.
The Resettable Total can be reset at any time by pressing the RESET key.
The instrument also has a test mode which can be entered by simultaneously
pressing all three front panel keys. The tests are as follows:
Lo Test By pressing the ACCUM TOTAL key, the low alarm output
will go low.
Hi Test By pressing the RESET key, the high alarm output:
a. will go low if CAL00 = 0 (high alarm output),
b. will output 100ms pulses every 0.5sec if CAL00 = 1 (scaled
pulse output).
Display Test By pressing the PROGRAM key, all segments of the display
will show.
To exit the test mode, simultaneously press all three front panel keys.
Note that when the input signal drops below 3.75mA (4-20mA input), a signal
error will occur. The display will alternate between the current total and the
word "SIGNAL". When the input signal drops below ≈3.5mA the Model 202A
shuts down saving totals in the non-volatile memory.
Introduction 7
1.3 INTRINSIC SAFETY CONSIDERATIONS
The Model 202A is certified for use in hazardous areas and has both CENELEC
and CSA NRTL/C approvals.
The Model 202A certification details are:
CENELEC Approval: Kema 98.E.1873.
Type of Protection: Ex ia.
Group: IIB.
Temperature Class: T4 at ambient temperature of 60°C.
CSA NRTL/C Approval
File Number: LR 104 840-5.
Type: Class 1, Groups C and D.
When installing in hazardous areas, the instrument will have to be installed
according to the guidelines given in section 6 and in accordance with standards
for wiring and installation in hazardous areas.
4-20mA Input
The input can be connected to IS circuits with the following maximum
values:
Ui = 28V
Ii = 93mA
Pi = 653mW.
Relay Outputs
The outputs can be connected to IS circuits with the following maximum
values:
Ui = 28V
Ii = 93mA
Pi = 653mW.
8 Specification
2. SPECIFICATION
General
Display: LCD, which is continuously powered.
Resettable Total: 7 digits with 10mm (0.4") high digits.
Resettable from front panel.
Accumulated Total: Displayed when the Accumulated Total button is
pressed.
Rate/Display: 5 digits with 8.5mm (0.33") high digits.
Span: The units of measure per timebase (eg. gallons/sec) is
programmable in the range 0.000001 to 999,999.
Decimal Points: Decimal Point positions are fully programmable for
both rate and total.
Timebase: Span can be programmed in units per second, minute,
hour or day.
Signal Type: 4-20mA.
4-20mA Input
Resolution and
Linearity: 0.05% of span.
Accuracy: 0.05% of span @ 25°C.
0.1% (typ) of span, full temperature range.
Update Time: 0.5 seconds.
Connection: Two wire.
Voltage Drop: 2.5 volts maximum.
Specification 9
Outputs
Type: Two open collector outputs suitable for driving DC
solenoids or external relays. The outputs provide high
and low flow alarms or pulse output and low flow
alarm.
Switching Power: 200mA. 30VDC maximum.
Saturation Voltage: 0.8VDC typical across the output in the "on" state.
Isolation: Both outputs are separately opto-isolated.
Pulse Duration: If CAL00 = 1 (scaled pulse output):
(for pulse output) a. 1ms if output frequency > 50Hz,
b. 10ms if output frequency is 5 ... 50Hz,
c. 100ms if output frequency is < 5Hz.
Physical
Temperature: Operating Temperature: -20°C to 60°C.
Dimensions: 97mm (3.8") high x 150mm (5.9") wide x 41mm
(1.6") deep (cable glands not included).
Protection: Sealed to Nema 4x or IP67 standards.
Cable Entry: By cable glands.
Wall Mounting: Universal Mounting Bracket supplied as standard.
Pipe Mounting: A galvanised metal bracket is available which enables
the Model 202A to be attached to a 2" vertical or
horizontal pipe.
Panel Mounting: Supplied with mounting brackets.
Terminals accessible from rear (Note that the panel
mount version is not watertight).
Cutout: 141mm (5.6") wide x 87mm (3.4") high.
10 Programming
3. PROGRAMMING
The Model 202A is fully programmable, with all parameters being stored in
non-volatile memory.
The Program Mode can be entered in the following way:
By removing the lower cover strip (ie. the dark grey strip along the
bottom of the enclosure) and replacing it the wrong side up. This brings
a small magnet on the inside of the cover strip in contact with a reed
switch inside the instrument.
The PROGRAM switch is used to step through the program (CAL sequences)
and the and keys on the front panel are used to change and increment the
flashing digits.
The CAL number is displayed on the lower display and the parameter is
displayed on the upper display.
3.1 PROGRAM STEPS
Step Comment
Programming 11
CAL 00
CAL 01
CAL 02
CAL 03
CAL 04
Pulse Output
0 = No pulse output, low and high alarms
1 = Scaled pulse output and low alarm
Span - whole numbers.
Span - digits after the decimal point.
The Span is the number of units of measure per
timebase (eg. litres/sec, Gal/min). The Span can be
programmed in the range of 0.000001 - 999,999.
See section 3.2.
Cutoff Point.
This determines the cutoff point as a fraction of Span.
See section 3.2.2.
Decimal Point for Rate Display.
The flowrate can be displayed with 0, 1, 2 or 3 decimal
point places.
CAL 05
Timebase for Rate.
The Rate can be displayed in units per second, minute,
hour or day.
0 = second
See section 3.2.
1 = minute
2 = hour
3 = day.
12 Programming
Step Comment
CAL 06
CAL 07
CAL 08
CAL 09
Filter.
Fluctuations in the flowrate can be filtered out so that
the Rate is held steady. The filter value is programmed
between 1 - 99 where "1" represents no filtering and 99
is maximum.
See section 3.4.
Decimal Point for Total Display.
The totals can be displayed with 0, 1, 2 or 3 decimal
points.
Total Conversion Factor - whole numbers.
Total Conversion Factor - digits after the decimal point.
The Total Conversion Factor enables the Rate to be
displayed in one engineering unit and the Totals to be
displayed in another engineering unit. The Total
Conversion Factor can be programmed in the range of
0.000001 - 999,999.
Set to 1.000 if totals and rate are in the same unit eg.
litres.
See section 3.3.
CAL 10
Low Alarm - whole numbers.
Step Comment
Programming 13
CAL 11
CAL 12
CAL 13
CAL 14
Low Alarm - digits after the decimal point.
CAL 10 & 11 program the flowrate below which the
low alarm relay will close. The value can be
programmed in the range 0 to 999,999.
High Alarm or Pulse Output Factor - whole numbers.
High Alarm or Pulse Output Factor - digits after the
decimal point.
CAL 12 & 13 program the flowrate above which the
high alarm relay will close. The value can be
programmed in the range 0 to 999,999.
If the pulse output is selected (see CAL 00), the value will
represent the total per pulse. eg. 5 litres per pulse.
Input Flow Relationship.
0 = Linear Input
1 = Square Root Input.
CAL 15
SOFT
Accumulated Total Reset.
CAL 15 displays the accumulated total which can be
reset by pressing and holding the RESET key for about
5 seconds.
Software Version.
14 Programming
3.2 CALCULATION OF RATE AND TOTAL
3.2.1 Analog Input
The flowrate, R, is calculated as follows:
R = SA if the linear relationship is selected
or R = S if a square law relationship is selected.A
where A = the input value.
S = the span.
At the minimum input (ie. 4mA), A = 0, and at the maximum input (ie. 20mA),
A = 1.
The Span, S, can be set during calibration anywhere in the range of 0.000001 to
999,999.
The Span, S, is programmed in units of volume per timebase (ie. litres/minute or
kilograms/hour). This also means that the Total will be displayed with the same
unit of volume, ie. litres or kilograms.
Programming 15
3.2.2 The Cutoff Point
Because many transducers do not always exactly transmit 4mA when they are at
zero rate, it is often necessary to define a rate below which no integration takes
place. This is termed the cutoff point and is programmed as a percentage of the
Span, S.
For example, if S = 2200 kg/min in a square law system, and the cutoff point is
set at 20.0%, the actual cutoff rate Rc can be determined as follows:
The cutoff rate is defined as:
Rc = 2200 A
At 20% cutoff,
Rc = 2200 x 0.2
= 440 kg/min
The value of A which would produce this cutoff is:
A = 0.04 (since = 0.2)0.04
and the input signal would be:
I = 16mA x 0.04 + 4mA
= 4.64mA
16 Programming
3.3 TOTAL CONVERSION
The Total Conversion feature enables the rate to be displayed in one engineering
unit (eg. gallons/minute) and the totals to be displayed in another engineering
unit (eg. barrels).
The Span is always programmed in the unit relating to Rate, and the Total
Conversion constant is a division factor which can be used to convert the totals to
the different unit. The Total Conversion factor affects the resettable and
accumulated totals.
For Example.
If the Rate is required in gallons per minute:
1. The Span would be programmed as gallons per minute
2. The timebase would be programmed as minutes
If the Totals are required in barrels:
3. The Total Conversion factor is programmed as 42 (there are 42
gallons in a barrel). All totals will now totalise in barrels.
Some common units are given below together with the Total Conversion constant
which should be programmed.
Rate* Totals TOTCON
Gallons (US)/ Barrels (oil) 42.000
Litres/ Kilolitres 1000
ml/ Litres 1000
Mgallons/ Acre-feet 0.32587
* Units per second, minute, hour or day. The timebase is programmed
separately during Programming.
Programming 17
3.4 FILTERING
Frequency fluctuations caused by pulsating flow through a flowmeter, often
makes the Rate impossible to read with any precision.
The Model 202A has a digital filter which will average out these fluctuations and
enable the Rate to be read to four digit accuracy. The ability to select a suitable
filtering level means that highly accurate and stable readings can be obtained
without excessive lag.
The diagram below shows a pulsating signal input together with the effect of
filtering.
Rate
Filtered Response
Unfiltered Response
Time
As a guideline to the degree of filtering to be used, the following table shows the
response to a step change in input. The value, CAL 06, is the filter constant
which is programmed during the Programming routine. The times for the
display value to reach 90% and 99% of full swing are given in seconds, for
different values of CAL 06.
18 Programming
A 90% 99%
1 0 0
2 1 2
4 2 4
6 3 6
10 5 11
15 8 17
20 11 22
25 14 28
35 20 40
45 25 51
60 34 69
75 43 86
90 52 103
99 57 113
Table 1 - Response to a step Input (in seconds).
Note that if CAL 06 is set to 01 there is no filtering of the input signal.
Programming 19
3.5 EXAMPLE
A vortex flowmeter has a maximum output of 20.538 litres/min at 20mA. It is
required to display the flowrate in litres/min with 1 decimal point and the total in
litres with no decimals. High and low alarms are required at 18 l/m and 2 l/m
respectively. The instrument is then programmed as follows.
CAL00 0 No Pulse Output
CAL01 00020 Span (Whole Numbers)
CAL02 5380 Span (Decimals)
03 0.05 Cutoff Point as a fraction of Span
04 1 Rate decimal position
05 1 Timebase
06 01 Filter disabled
07 0 Total decimal position
08 0001 Total Conversion (set to 1.0000)
09 0000 Total Conversion (decimals)
10 00002 Low Alarm
11 0000 Low Alarm
12 00018 High Alarm
13 0000 High Alarm
14 0 Linear Input
15 xxxx Accumulated Totals
SOFT 202A1.11 Software Version
20 Signal Input
4. SIGNAL INPUT
The signal input is on terminals 3 and 4 and can be connected as follows:
Alarm & Pulse Outputs 21
5. ALARM & PULSE
OUTPUTS
Open collector outputs are provided for high and low flowrate alarms. The
output can sink up to 200mA and can be used to power external relays, lights or
audible alarms. The outputs are internally protected against voltage spikes
caused by relays and coils.
Both outputs are separately isolated via opto isolators.
As an alternative to a high flowrate alarm, the output on terminals 7 and 8 can be
programmed to output a scaled pulse output.
The switching points can be programmed during the setup mode and the low
flow alarm will switch on whenever the flowrate drops below the programmed
flowrate. Similarly, the high alarm switches on whenever the flow exceeds the
high setpoint.
If a Scaled Pulse Output is programmed, a pulse will be output every preset value
of the total. For example, if the total is in litres, then programming 5 will output
one pulse every 5 litres. The duration of pulses is adjusted automatically to the
output frequency.
Specification for Alarm Outputs
Maximum Current (sink): 200mA.
Maximum Voltage: 30VDC.
Saturation Voltage: 0.8VDC across Outputs when in the "on"
state.
Isolation: Both outputs are separately isolated.
Pulse Frequency: 500Hz maximum.
Pulse Duration: 1ms if output frequency > 50Hz.
10ms if output frequency = 5 ... 50Hz.
100ms if output frequency < 5Hz.
22 Alarm & Pulse Outputs
Connections
Intrinsic Safety Connections 23
6. INTRINSIC SAFETY
CONNECTIONS
When installing the Model 202A in hazardous areas, the wiring and installation
must comply with appropriate installation standards.
The approval uses entity parameters and an associated apparatus type approval
on the input/output connections to the 4-20mA current loop and alarms. The
4-20mA input and alarm outputs must, therefore, only be connected as shown on
the following page, to barriers with the specified parameters.
The Model 202A will connect directly to a 4-20mA current loop and alarms,
provided they do not exceed the following input parameters:
Ui = 28V
Ii = 93mA
Pi = 653mW
The internal capacitance seen on the input (terminals 3 & 4) is 0.02uF while the
internal capacitance seen on the output (terminals 5-8) is 0.1uF maximum.
Inductance is negligibly small on both the input and output.
Outputs
The two open collector outputs must only be connected to certified IS equipment
via barriers as shown on the following page. Only certified intrinsically safe
solenoids may be used for IS applications.
24 Intrinsic Safety Connections
Installation 25
7. INSTALLATION
7.1 WALL MOUNTING
A wall mounting bracket is supplied with each instrument. The bracket should
be attached to the wall using round head screws (do not use counter sunk screws).
The bracket is mounted with the "tray" section at the bottom. The instrument is
then attached to the bracket at the bottom with two screws (see diagram below).
26 Installation
7.2 PANEL MOUNT VERSION
The panel mount version of the Model 202A is supplied with two panel mount
brackets and plug-in terminals which are accessible from the rear of the
instrument.
A diagram of the rear panel is shown below.
The cutout for the panel mount version is 141mm (5.55") wide x 87mm (3.43")
high.
Installation 27
7.3 REMOVING THE FRONT PANEL
The front of the instrument is removed as follows:
1. Remove both the top and bottom cover strips (ie. the dark plastic strips on
the front) by levering a screwdriver under one end.
2. Undo the seven screws retaining the front. Note that the screws should
not be removed from the front panel as they are retained by O-rings.
3. Pull the front panel free from the housing.
Replacing the front panel of the instrument is the reverse procedure. However,
ensure that the front panel is aligned at both connector points before tightening
the screws.
28 Installation
Installation 29
7.4 THE MAIN ELECTRONICS
The front section of the housing contains the microprocessor and display.
It is also possible to adjust the display contrast via a small potentiometer on the
board. The DISPLAY CONTRAST control is shown below and this can be
adjusted for optimum contrast.
Adjacent to this control is a RESET switch which can be used to reset the
microprocessor. Note that pressing this button will Set all totals to zero and
calibration parameters to default values.
The Main Electronics
30 Installation
7.5 WIRING
When connecting the Model 202A, it is goods practice to use shielded cable.
In order to comply with the requirements for Electromagnetic Compatibility, as
per EMC-Directive 89/336/EEC of the Council of the European Community, this
wiring practice is mandatory.
7.6 TERMINAL DESIGNATIONS
4-20mA Input
3 4-20mA (-)
4 4-20mA (+)
Outputs
5 Low Alarm (-)
6 Low Alarm (+)
7 High Alarm (-) or Pulse Output (-)
8 High Alarm (+) or Pulse Output (+)
Installation 31
32 Index
Index
A
Accumulated Total, 6
C
CAL Sequences, 10
Cutoff Point, 11
D
Decimal Point, 11
Display, 8
Display Test, 6
F
Filtering, 17
H
Hi Test, 6
High Alarm, 13
I
Installation, 25
Intrinsic Safety, 7
L
Lo Test, 6
Low Alarm, 12
O
Operating
Temperature, 9
Operation, 6
P
Panel Mount, 26
Programming, 10
Protection, 9
Pulsating Signal, 17
Pulse Output, 21
R
Rate, 6
Removing the Front
Panel, 27
Resettable Total, 6
Response, 18
S
Span, 11
Specification, 8
T
Temperature, 9
Terminal
Designations, 31
Test Mode, 6
Timebase, 11
Total Conversion, 16
M
Model Number, 4
W
Wall Mounting, 25
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