BEKA BA574C User manual

BA574C
field mounting
indicating temperature
transmitter
issue 4
Issue: 4
26th September 2008

1. Description
2. Operation
2.1 Controls
3. Electrical system design
4. Installation
4.1 Location
4.2 Installation procedure
4.3 EMC
5. Programming and calibration
5.1 Summary ofProgrammeMenu
functions.
5.2 Transmitter input
5.3 For thermocouple inputs
5.3.1 Types of thermocouple
5.3.2 Display units
5.3.3 Display resolution
5.3.4 Cold junction compensation
5.3.5 Input open circuit drive
5.4 For resistance thermometer inputs
5.4.1 Type of resistance thermometer
5.4.2 Display units
5.4.3 Display resolution
5.5 For voltage inputs
5.5.1 Position of display decimal point
5.5.2 Low input & display calibration
5.5.3 High input & display calibration
5.6 4/20mA output current calibration
5.7 Security code
5.8 Calibrating the internal references
5.8.1 Conditioning internal references
5.8.2 Voltage input reference
5.8.3 3-wire RTD reference
5.8.4 4-wire RTD reference
5.8.5 Output current reference
6. Trim menu
6.1 Calibration procedure using Trim menu
6.2 Periodic re-calibration using Trim menu
7. Calibration example
8. Maintenance
8.1 Fault finding during commissioning
8.2 Fault finding after commissioning
8.3 Servicing
8.4 Guarantee
8.5 Customer comments
Accessories
9. Identification and mounting
9.1 Engraved scale and tag plates
9.2 Pipe mounting kits
9.3 Panel mounting kit
10. Alarms
10.1.1 Solid state output
10.1.2 Programming and adjustment
10.2 Summary of programmable functions
10.3 Description of programmable functions
10.3.1 Alarm enable
10.3.2 Setpointadjustment
10.3.3 Alarm function
10.3.4 Alarm output status
10.3.5 Hysteresis
10.3.6 Alarm delay
10.3.7 Alarm silence time
10.3.8 Access setpoint
10.4 Adjusting alarmsetpoints from display
mode
11. Backlight
CONTENTS
The BA574C is CE marked to show compliance with the European EMC Directive2004/108/EC

3
A Quick Guide to the Use of this Instruction Manual
Your BA574C has been factory set to the requirements specified on your purchase order.
If no requirements were given, the instrument will be supplied with default settings i.e. 3 wire
RTD input; high resolution display in °C; 4 to 20mA output corresponding to an input and
display of 0.0 to 100.0°C.
If the BA574C is set to your requirements before putting it into use you should refer to:
Section 3 Electrical System Design
Section 4 Installation
Section 2.1 Controls
If optional alarms are fitted you should refer to Section 10. You will also find the 'Trim' menu
described in Section 6 useful if you wish to calibrate the complete control loop.
If the BA574C has been supplied with default settings and you wish to change these you will
need to refer to:
Section 5 Programming and Calibration.
This section explains the programme functions of the push-buttons and leads you through
the various stages of programming the unit. Among the sub-divisions of Section 5 you will
find information on setting up for
Section 5.3 Themocoupleinput
Section 5.4 Resistance thermometer input
Section 5.5 Voltage inputs
A word of warning: Section 5.8 explains how you can calibrate the instrument's internal
references. It is only necessary to carry out this operation if you will be using these internal
references to calibrate the instrument display, i.e not using an external calibrator, and then
only annual or less frequent adjustment is required. It is not necessary to calibrate these
references before putting the unit into operation, we've already done that for you. For
this reason the calibration section of the programme menu is protected by an additional
security code. You should only enter this section of the programme if you are sure that you
want to carry out this calibration.
By following the notes in this manual you should be able to set up your BA574C without any
problem. If you do run into difficulties however Section 8 (Maintenance) provides some
guidance on typical problems you may find during commissioning. If you still have
difficulties please contact our Sales Department (01462 438301). Our Sales Engineers
will be able to talk you through thetheprocedure.

4

1. DESCRIPTION
The BA574C is a 4/20mA loop powered
temperature transmitter incorporating a large easy
to read display. The instrument may be
programmed on-site to accept most common
thermocouples and resistance thermometers, and
will provide a linear 4/20mA output proportional to
temperature, plus a display in oC or oF. Voltage
inputs may be scaled allowing the BA574C to
display variables other than temperature.
Optional alarms provide two galvanically isolated
solid state outputs which may be independently
programmed as high or low trips. For installations
in poorly illuminated areas an optional display
backlightis available.
The BA574C transmitter is available in a glass
reinforced polyester (GRP), or an epoxy painted
aluminiumenclosure, both provideIP66 protection.
Fig 1 Simplified block diagram
2. OPERATION
Fig 1 shows a simplified block diagram of the
transmitter. The input signal, which may be from a
thermocouple, resistance thermometer or a dc
voltage, is digitised and transferred to the
instrument processor via an optical isolator. The
processor scales the signal and for temperature
measurement applies linearisation using look-up
tables stored in permanent memory. The resulting
temperature is shown on the internal display and
controls the 4/20mA output current. The
transmitter and the optional alarms are powered
from the 4/20mA current loop, but the optional
display backlightrequires a separate supply.
Each time power is applied to the instrument,
initialisation is performed. After a short delay the
following display sequence occurs:
-1.8.8.8.8 Display test in which all
segments of the display
are activated for 2.5
seconds.
. . . . For 1 second
0 For less than 0.5
seconds.
Input signal Using calibration
displayed information stored in
instrument memory.
2.1 Controls
All functions of the transmitter can be programmed
on-site via four push-buttons which are located
behind the enclosure cover - see Fig 3. In the
display mode i.e. when the transmitter is displaying
the input signal, these push-buttons have the
following functions. The 4/20mA output current is
not affected by operating these push-buttons, and
when released, the input signal will again be
displayed.
Button Function
Down While this button is pushed the
transmitter will show the display
corresponding to a 4mA output.
Up While this button is pushed the
transmitter will show the display
corresponding to a 20mA output.
For transmitters fitted with alarms
E+Up While these buttons are pushed the
transmitter will display setpoint 1.
E+Down While these buttons are pushed the
transmitter will display setpoint 2.
It is also possible to adjust the two alarm setpoints
from the display mode - see section 10.4
5

3. ELECTRICAL SYSTEM DESIGN
A BA574C indicating transmitter will operate from
any dc voltage between 10 and 30V. When
designing a loop it is therefore necessary to ensure
that the voltage between terminals 5 & 6 is
between 10 and 30V at all output currents.
Fig 2 Typical temperature measuring loop
Considering the temperature measuring loop shown
in Fig 2. The sum of the maximum voltage drops of
all the components in the loop must be less than the
minimum power supply voltage.
With an output current of20mA:
Minimum operating voltage ofBA574C 10.0V
Maximum voltage drop caused by
250ohmload 5.0V
(250ohmsx 20mA)
Maximum voltage drop caused by cable 0.2V
resistance (10ohmsx 20mA)
-------
Total maximum voltage drop 15.2V
Therefore the power supply must have an output
greater than 15.2V
4. INSTALLATION
4.1 Location
The BA574C indicating transmitter can be supplied
in either a glass reinforced polyester (GRP), or an
epoxy painted aluminium enclosure. Both provide
IP66 protection and have a toughened glass
window and stainless steel fittings. The GRP
enclosure is suitable for most industrial installations
including off-shore and waste water treatment
applications. For installations where solvents may
be present, the aluminium enclosure provides
maximum protection.
Fig 3 BA574C installation procedure
Both enclosures are surface mounting, but can be
pipe or panel mounted using the accessory kits
described in section 9.
To simplify installation, the enclosure may be
installed and the field wiring terminated prior to the
transmitter assembly being fitted. Terminal 7 is
internally connected to the radio frequency screen
in the GRP enclosure and to the case in the
aluminiumenclosure .
6

4.2 Installation Procedure
Fig 3 illustrates the instrument installation
procedure.
a. Remove the enclosure cover by unscrewing
the four captive 'A' screws.
b. Remove the transmitter assembly from the
enclosure by unscrewing the three captive 'B'
screws and unplugging the flexible cable(s).
c. Mount the enclosure on a flat surface and
secure with screws or bolts through the four
corner 'C' holes. Alternatively use one of the
pipe or panel mounting kits described in
sections 9.2 and 9.3.
d. Remove the temporary dust seals from the
cable entries and install the required glands,
conduit fittings or blanking plugs.
e. Connect the field wiring to the terminals as
shown in Fig 4.
f. Replace the transmitter assembly and evenly
tighten the three 'B' screws.
g. Replace the enclosure cover and evenly
tighten the four 'A' screws.
Fig 4 Dimensions and terminal connections
4.3 EMC
The BA574C complies with the requirements of the
European EMC Directive 2004/108/EEC. For
specified immunity all wiring should be in screened
twisted pairs.
5. PROGRAMMING AND CALIBRATION
The BA574C is programmed and calibrated via four
push-buttons which are located behind the enclo-
sure cover. All the functions are contained in two
easy to use menus, the Programme Menu and the
Trim Menu, which are shown diagramatically in Figs
5A, 5B and 7.
The Programme Menu contains all the transmitter
parameters and enables calibration to be
performed against the internal transmitter refer-
ences.
The Trim Menu enables the transmitter display and
the 4/20mA output current to be calibrated against
an external standard, such as a voltage source or
temperature calibrator. A complete loop may be
calibrated using this menu to compensate for errors
resulting from primary element and load
inaccuracies.
Each function in the programme menu is summa-
rised in section 5.1 which includes cross references
to more detailed information in following sections.
Although this simple menu driven system enables
most adjustments to be made without repeated
reference to this manual, we recommend that the
summary of the Programme Menu, calibration
procedure using the Trim Menu and the calibration
example in sections 5.1, 6.1 and 7 are read prior
to changing function or calibrating the transmitter.
Figs 5A, 5B and 7 show the structure of both
menus.
Details of the Trim Menu are contained in section 6
which also describes periodic calibration.
When the transmitter is fitted with alarms additional
functions are added to the programme menu.
These are described in section 10.
Throughout this manual push-buttons are shown in
italics e.g. P or Up push-button, and legends
displayed by the indicator are shown within inverted
commas e.g. 'CAL' and ' ALr2'.
Access to the Programme Menu is obtained by
operating the Pand Epush-buttons simultaneously.
If the transmitter is not protected by a security
code the first parameter 'InPut' will be displayed. If
the transmitter is protected by a security code,
'COdE' will be displayed first.
7

Pressing Pagain will enable the security code to be
entered digit by digit using the Up and Down
buttons to change the flashing digit, and the Ppush-
button to move to the next digit. If the correct
code is entered pressing Ewill cause the first
parameter 'InPut' to be displayed. If an incorrect
code is entered, or no button is pressed for ten
seconds, the transmitter will automatically return to
the operating mode.
When the transmitter is in the Programme Menu the
4/20mA output current will remain locked at the
value prior to starting programming, the output will
therefore not respond to any input change.
However, calibration of the 4/20mA output via the
'CAL' function, or re-calibration of the 4/20mA
reference via the 'Cond' function will change the
output current.
Once within the Programme Menu the required
parameter can be reached by scrolling through the
functions using the Up and Down push-buttons as
shown in Figs 5A and 5B. When returning to the
display mode following changes to any parameters,
the transmitter will display four
decimal points for a few seconds while the new
information is stored in permanent memory.
All new BA574C indicators are supplied calibrated
as requested at the time of ordering. If calibration
is not requested, the transmitter will be set for 3
wire RTD input with 4 to 20mA output correspond-
ing to a display of 0.0oC to 100.0oC.
5.1 Summary of ProgrammeMenu functions
The parameters which may be programmed vary
depending upon which input is selected. For:
Thermocouple and resistance
thermometer inputs
The BA574C transmitter will always display
sensor temperature. Programming allows the
display to be in degrees Centigrade or Fahren-
heit, and for the display resolution to be
selected.
Zero and span of the 4/20mA output current
may be programmed to represent any display
range.
Voltage input
The display may be programmed to show the
input voltage in any engineering units.
Zero and span of the 4/20mA output current
may be independently programmed to repre-
sent any displayed value.
Each of the functions in the Programme Menu is
described in the following summary with a cross
reference to more detailed information. Figs 5A
and 5B illustrate the location of each function within
the menu.
Summary of ProgrammeMenu functions
Display Functions
'InPut' Transmitter input
Conditions the transmitter to accept
thermocouple'tHC', resistance
thermometer 'rtd' or a voltage 'UOLt'
input.
See section 5.2
For Thermocouple Inputs
'tYPE' Sensor type
Selects type of thermocouple input.
See section 5.3.1
'dEg' Units of display
Sets display to oC or oF.
See section 5.3.2
'rESn' Display resolution
Selects low or high display resolution.
See section 5.3.3
'CJC' Cold junction compensation
Turns thermocouple cold junction
compensation ON or OFF.
See section 5.3.4
'burn' Input open circuit drive
Selects up scale drive, down scale drive
or no drive when input is open circuit.
See section 5.3.5
For Resistance Thermometer Inputs
'tYPE' Sensor type
Selects 3-wire, 4-wire or differential
Pt100 resistance thermometer input.
See section 5.4.1
'dEg' Units of display
Sets display to oC or oF.
See section 5.4.2
'rESn' Display resolution
Selects low or high display resolution.
See section 5.4.3
8

Summary of ProgrammeMenu functions
Display Functions
For Voltage Inputs
''d.P.' Decimal point
Positions the dummy decimal point
between any of the display digits or
turns it off.
See section 5.5.1
'In-LO' Low input sub-menu
Enables the lower voltage input'InPut'
and the corresponding display'diSP' to
be defined.
See section 5.5.2
'In-HI' High input sub-menu
Enables the higher voltage input'InPut'
and the corresponding display'diSP' to
be defined.
See section 5.5.3
Other functions
'CAL' Calibration of 4/20mAoutput
This sub-menu defines the relationship
between the transmitter 4/20mA output
and the transmitter display. 'ZEro'
defines the display at which the output
is 4mA, and 'SPAn'the display at which
the output is20mA.
See section 5.6
'COdE' Security code
Defines a four digit numeric code which
must be entered to gain access to the
programme and the trim menus.
Default code 0000 disables the security
function and allows unrestricted access
to all functions in theprogramme and
trim menus.
See section 5.7
'Cond' Conditioning of internal references
WARNING!
This sub-menu is password
protected. It is not necessary to
carry out this operation before
putting the instrument into
service.
This sub-menu enables the internal
references to be calibrated against
external voltage, resistance and current
standards. It is normally only
necessary to use this function once per
year.
If the Trim Menu is used to calibrate the
transmitter, the internal references do
not require re-calibration.
See section 5.8
9

10

11

5.2 Transmitter input 'InPut'
This function conditions the transmitter to accept a
thermocouple 'tHC', resistance thermometer 'rtd' or
a voltage 'UOLt' input. To define the transmitter
input select 'InPut' from the Programme Menu and
press Pwhich will reveal the current setting. This
setting may be changed by scrolling through the
menu using the Up or Down buttons. When the
required input is displayed, pressing Pwill reveal a
sub-menu enabling the type of sensor to be
selected and associated parameters programmed.
5.3 For thermocouple inputs
5.3.1 Type of thermocouple 'tYPE'
After selecting a thermocouple input, pressing Pwill
reveal the 'tYPE' sub-menu which contains seven
different thermocouples:
Type Display Standard
E E BS4937 Part 6 : 1974
J J BS4437 Part 3 : 1973
K h BS4437 Part 4 : 1973
N n BS4437 Part 8 : 1986
R r BS4937 Part 2 : 1973
T t BS4937 Part 5 : 1973
Pallaplat PALL Pfaulder BA302e
Pressing Pagain will display the current type of
thermocouple which may be changed by scroll
through the menu using the Up or Down buttons.
When the required type is displayed, press Eto
return to the sub-menu.
5.3.2 Display units 'dEg'
The transmitter display may be in degrees
centigrade or Fahrenheit. To check or change the
display units select 'dEg' from the sub-menu and
press Pto reveal the current setting. The setting
may be changed by pressing the Up or Down
button. When the required units is displayed, press
Eto return to the sub-menu.
5.3.3 Display resolution 'rESn'
The output of each type of thermocouple can be
displayed with high or low resolution as shown
below. Low resolution can improve the readability
of a noisy or rapidly changing display, but does not
degrade the performance of the 4/20mA analogue
output. High resolution is only available when the
transmitter is displaying temperature in oC. When oF
is selected the resolution is always one degree.
To check or change the display resolution select
'rESn' from the sub-menu and press Pto reveal the
current setting. The setting may be changed by
pressing the Up or Down button. When the required
resolution has been selected, press Eto return to
the sub-menu.
Display Resolution
Type Low (Lo) High (Hi)
E1
oC 0.1oC
J1
oC 0.1oC
K1
oC 0.2oC *
N1
oC 0.2oC *
R1
oC 0.4oC *
T1
oC 0.1oC
Pallaplat 1oC 0.2oC *
*Worst case high resolution figures are
quoted, at most temperatures resolution will
be greater.
5.3.4 Cold junction compensation 'CJC'
The temperature of the transmitter input terminals,
the thermocouple cold junction, is measured and
added to the output from the thermocouple so that
the transmitter displays and transmits the
temperature relative to zero degrees centigrade or
Fahrenheit. If cold junction compensation is not
required, e.g. for differential measurement with two
thermocouples, this function enables the cold
junction compensation to be turned off.
To turn the cold junction compensation on or off
select 'CJC' from the sub-menu and press Pto
reveal the current status. The setting may be
changed by pressing the Up or Down button. When
set as required press Eto return to the sub-menu.
5.3.5 Input open circuit drive 'burn'
If the thermocouple fails and becomes open circuit,
the transmitter can be conditioned to drive the
display and the 4/20mA output current up or down
into a safe condition. Alternatively the drive may be
turned off which will result in the display and the
4/20mA output current drifting towards zero.
To check or change the input open circuit drive
select 'burn' from the sub-menu and press Pto
reveal the current setting. The setting may be
changed by pressing the Up or Down button. When
the required setting has been selected, press Eto
return to the sub-menu.
12

5.4 For resistance thermometer inputs
5.4.1 Types of resistance thermometer 'tYPE'
The transmitter may be conditioned to accept
3-wire, 4-wire or differential Pt100 resistance
thermometers.
After selecting resistance thermometer input from
the 'InPut' sub-menu, press Pto reveal the 'tYPE'
sub-menu. Press Pagain to display the current
type resistance thermometer which may be
changed by scrolling through the menu using the Up
or Down buttons. When the required type is
displayed, press Eto return to the sub-menu.
5.4.2 Display units 'dEg'
The transmitter display may be in degrees
centigrade or Fahrenheit. To check or change the
display units select 'dEg' from the sub-menu and
press Pto reveal the current setting. The setting
may be changed by pressing the Up or Down
button. When the required unit is displayed, press E
to return to the sub-menu.
5.4.3 Display resolution 'rESn'
The output of the resistance thermometer can be
displayed with high or low resolution as shown
below. Low resolution can improve the readability
of a noisy or rapidly changing display, but does not
degrade the performance of the 4/20mA analogue
output. High resolution is only available when the
transmitter is displaying temperature in oC. When oF
is selected the resolution is always one degree.
To check or change the display resolution select
'rESn' from the sub-menu and press P to reveal the
current setting. The setting may be changed by
pressing the Up or Down button. When the required
resolution has been selected, press Eto return to
the sub-menu.
Display Resolution
Low High
1oC 0.1oC
5.5 For Voltage Inputs
When the transmitter is conditioned for a voltage
input both the input voltage range and the
corresponding display must be programmed.
5.5.1 Position of display decimal point 'd.P.'
A dummy decimal point can be positioned between
any of the display digits or it may be absent.
After selecting voltage input from the 'InPut' menu,
press Pto reveal the 'd.P.' sub-menu. Press P
again to display the current decimal point position.
The decimal point can be moved or turned off by
pressing the Up or Down push-button, followed by
Eto return to the sub-menu.
5.5.2 Low input & display calibration 'In-LO'
This function defines the lower voltage input and the
corresponding transmitter display. See example
below:
Input Transmitter
mV Display
-10.00 -3.000 Low input / display
12.55 3.765 High input / display
The calibration is performed using the internal
references and may be made with any transmitter
input voltage.
Select 'In-LO' from the menu and press Pwhich will
access a sub-menu containing two functions 'InPut'
and ''dISP'.
Select the input voltage 'InPut' and press Pwhich
will cause the specified lower input millivoltage to
be displayed in the form XX.XX The flashing digit of
the input voltage can be changed by pressing the
Up or Down buttons. When the first digit is correct,
pressing Pwill transfer control to the next digit.
When the least significant digit has been adjusted,
press Eto return to the 'InPut' prompt, from which
the display prompt 'dISP' can be selected by
pressing theUp or Down button.
Pressing Pwill reveal the transmitter display
corresponding to the specified low input voltage.
The position of the dummy decimal point will be as
defined by function'd.P.' - see section 5.5.1
The flashing digit of the display can be changed by
pressing the Up or Down buttons. When the first
digit is correct, pressing Pwill transfer control to
the next digit. When the least significant digit has
been adjusted, press Eto return to the ''dISP'
prompt.
5.5.3 High input & display calibration 'In-HI'
This function defines the higher voltage input and
the corresponding transmitter display. See
example below:
Input Transmitter
mV Display
-10.00 -3.000 Low input / display
12.55 3.765 High input / display
13

The calibration is performed using the internal
references and may be made with any transmitter
input voltage.
Select 'In-HI' from the menu and press Pwhich will
access a sub-menu containing two functions 'InPut'
and ''dISP'.
Select the input voltage 'InPut' and press Pwhich
will cause the specified higher input millivoltage to
be displayed in the form XX.XX The flashing digit of
the input voltage can be changed by pressing the
Up or Down buttons. When the first digit is correct,
pressing Pwill transfer control to the next digit.
When the least significant digit has been adjusted,
press Eto return to the 'InPut' prompt, from which
the display prompt 'dISP' can be selected by
pressing theUp or Down button.
Pressing Pwill reveal the transmitter display
corresponding to the specified higher input voltage.
The position of the dummy decimal point will be as
defined by function'd.P.' - see section 5.5.1
The flashing digit of the display can be changed by
pressing the Up or Down buttons. When the first
digit is correct, pressing Pwill transfer control to
the next digit. When the least significant digit has
been adjusted, press Eto return to the ''dISP'
prompt.
5.6 4/20mAoutput current calibration 'CAL'
This sub-menu defines the relationship between the
transmitter display and the 4/20mA output current.
The transmitter output current is derived from the
transmitter display and will change if the display
calibration is changed. 'ZEro' defines the display
at which the output is 4mA, and 'SPAn' the display
at which the output is20mA.
To calibrate the output current select 'CAL' from the
programme menu and press Pwhich will access a
sub-menu containing two functions. Select 'ZEro'
and press Pwhich will show the transmitter display
at which the output current is 4mA. The flashing
digit of the display can be changed by pressing the
Up or Down buttons. When the first digit is correct,
pressing Pwill transfer control to the next digit.
When the least significant digit has been adjusted,
press Eto return to the 'ZEro' prompt, from which
the span prompt 'SPAn' can be selected by
pressing theUp or Down button.
Press Pto show the transmitter display at which
the output current is 20mA. The flashing digit of the
display can be changed by pressing the Up or
Down buttons.
When the first digit is correct, pressing Pwill
transfer control to the next digit. When the least
significant digit has been adjusted, press Eto
return to the 'SPAn'prompt.
Note: If a complete loop including a primary
element, BA574C temperature transmitter and a
load are being calibrated, the Trim Menu is the
preferred method. It allows the transmitter display
and output current to be adjusted to compensate
for inaccuracies. Details of the trim menu are
contained in section 6 which also describes periodic
calibration.
5.7 Security Code 'COdE'
Access to the Programme and Trim Menus may be
protected by a four digit numerical security code
which must be entered before access is granted.
New instruments are programmed with the default
security code 0000 which allows unrestricted
access to both menus.
To enter a new security code select 'COdE' from
the programme menu and press Pwhich will cause
the transmitter to display the current security code.
Each digit of the code can be changed using the Up
and Down push-buttons, and the P button to move
to the next digit. When the required code has been
entered press Eto return to the main menu. The
revised security code will be activated when the
transmitter is returned to the display mode.
If the security code is lost, access to the
programme and trim menus can be obtained by
putting the security link in the override position - see
Fig 6. The security code can then be viewed by
selecting'COdE' from the menu and pressingP.
Fig 6 Location of security code override link
14

5.8 Calibrating the internal references
WARNING!
Changing the internal references will
alter the instrument performance. Do
not not attempt to recalibrate these
references unless you have adequate
test equipment and have read the
following instructions. For routine
calibration of the the instrument use the
Trim Menu described in section 6.
If the internal references are used for calibrating
the BA574C transmitter they may require periodic
checking against external standards. Annual checks
will produce acceptable performance, although less
frequent checks are usually adequate.
If the BA574C transmitter is calibrated against an
external voltage, resistance or temperature
calibrator using the Trim Menu, the internal
references should never need re-calibrating.
Details of the Trim Menu are contained in
section 6.
There are four internal references:
Voltage input
3-wire RTD
4-wire RTD
Current output
The input voltage reference must be adjusted first
irrespective of the transmitter application, but it is
only necessary to adjust the other three references
if the function to which they relate is being used.
For example, a BA574C with a thermocouple input
from which the 4/20mA output current is being used
would require the voltage input and the current
output reference adjusting.
5.8.1 Conditioning internal references: 'Cond'
WARNING!
Changing the internal references will
alter the instrument performance. Do
not not attempt to recalibrate these
references unless you have adequate
test equipment and have read the
following instructions. For routine
calibration of the the instrument use the
Trim Menu described in section 6.
These functions are contained in a protected
sub-menu to minimise the possibility of accidental
adjustment. Select 'Cond' from the menu and press
P. The transmitter will display '0000'.
Using the Up and Down buttons and the Pbutton to
move to the next digit enter the password 'SurE.
(Note that 'S' is entered as '5') There is a ten
second time-out on password entry. Pressing Ewill
then give access to the sub-menu containing the
four refences.
5.8.2 Voltage input reference 'U.IP'
With the BA574C input terminals connected to an
accurate voltage calibrator, select 'U.IP' from the
'Cond' sub-menu and press P. The transmitter will
respond by displaying 'Lo' which is a request for an
accurate -75.000mV input. When the input is
correct press Pto store this figure in permanent
memory. The transmitter will display scrolling
decimal points while the reference is being updated
and will then return to the'Lo' prompt.
Select 'Hi' from the sub-menu which is a request for
an accurate +75.000mV input. When the input is
correct press Pto store this figure in permanent
memory. The transmitter will display scrolling
decimal points while the reference is being updated
and will then return to the 'Hi' prompt. This
completes adjustment of the voltage input
reference.
5.8.3 3-wire RTD reference '3rtd'
This adjustment, which is only necessary if the
transmitter is used with a three wire resistance
thermometer, should be performed after the
voltage reference has been calibrated. To adjust
the 3-wire RTD reference the resistance
thermometer should be replaced by a 100 ohm
standard resistor or calibrator, with the
compensation loop remaining connected between
terminals 3 and 4. Although it is preferable to
make this substitution as close to the RTD as
possible, transmitters may be calibrated in a
workshop.
Select '3rtd' from the 'Cond' sub-menu and press P.
The transmitter will display scrolling decimal points
while the reference is being updated followed by
'Ent' prior to returning to the '3rtd' prompt. This
completes adjustment of this reference.
5.8.4 4-wire RTD reference '4rtd'
This adjustment, which is only necessary if the
transmitter is used with a four wire resistance
thermometer, should be performed after the
voltage reference has been calibrated. To adjust
the 4-wire RTD reference the resistance
thermometer should be replaced by a 100 ohm
standard resistor or calibrator, with both
compensation loops from terminals 1 and 4
connected at the standard resistor or calibrator.
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It is preferable to make this substitution as close to
the RTD as possible, but if necessary the
transmitter may be calibrated in a workshop.
Select '4rtd' from the 'Cond' sub-menu and press P.
The transmitter will display scrolling decimal points
while the reference is being updated followed by
'Ent' prior to returning to the '4rtd' prompt. This
completes adjustment of this reference.
5.8.5 Output current reference 'OP'
Warning: ensure plant safety
before performing this adjustment
This adjustment is only necessary if the transmitter
4/20mA output current is used. A method of
accurately measuring the transmitter output current,
such as DVM, is required to calibrate this
reference.
Select 'OP' from the 'Cond' sub-menu and press P,
the transmitter will display 'SurE'. If it is safe to
change the transmitter output current between 4
and 20mA continue by pressing P. The transmitter
will display 'ZEro', pressing P again will change the
display to '.004A' and the transmitter output current
to approximately 4mA. The transmitter output
current shown on the external current measuring
instrument should be adjusted to 4.000 ±0.001mA
using the transmitter Up and Down buttons. When
correct press the E push-button to return to the
'ZEro' prompt.
To adjust the 20mA output current reference select
the 'SPAn' prompt by operating the Up or Down
button. Pressing Pwill change the display to
'.020A' and the transmitter output current to
approximately 20mA. The transmitter output
current shown on the external current measuring
instrument should be adjusted to 20.000± 0.001mA
using the transmitter Up and Down buttons. When
correct press the Epush-button twice to return to
the 'OP' prompt. This completes adjustment of this
reference.
6. TRIM MENU
The Trim Menu enables the BA574C transmitter to
be adjusted using an external voltage, resistance or
temperature calibrator. For maximum accuracy the
complete loop including the thermocouple or
resistance thermometer may be calibrated by
heating or cooling the primary element.
Before using the Trim Menu all the functions in the
'InPut' and 'CAL' sections of the programme menu
must be defined, including the 4/20mA output
range, and for voltage inputs the input and display
ranges.
If a voltage calibrator is used to simulate a
thermocouple the transmitter cold junction
compensation must be turned off. Alternatively, the
temperature at the BA574C input terminals may be
measured and the voltage calibrator corrected for
ambient temperature, although this is likely to
produce less accurate results.
6.1 Calibration procedure using Trim Menu
The structure of the Trim Menu is shown in Fig 7.
Access to the menu is obtained by operating the P
and Down push-buttons simultaneously. If the
transmitter is not protected by a security code the
first parameter 'ZEro' will be displayed. If the
transmitter is protected by a security code, 'COdE'
will be displayed first. Pressing Pagain will enable
the security code to be entered digit by digit, using
the Up and Down buttons to change the flashing
digit, and the Ppush-button to move to the next
digit. If the correct code is entered pressing Ewill
cause the first parameter 'ZEro' to be displayed.
If an incorrect code is entered, or if no button is
pressed for ten seconds, the transmitter will
automatically return to the display mode.
Fig 7 Trim Menu
The 'ZEro' sub-menu allows the transmitter display
and output current to be independently trimmed at
the bottom of the input range. To make the adjust-
ment connect a calibrator to the transmitter input
terminals to simulate minimum input, or place the
primary element in a vessel at the minimum
temperature. With 'ZEro' displayed, pressing the P
push-button will cause the temperature display to
return.
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If the display does not correspond with the input
calibrator or the temperature of the primary
element, operate the Up or Down button until the
transmitter display is correct. Immediately the Up
or Down button is operated the annunicator in the
top left hand corner of the display will be activated
to warn that any changes in the input signal will be
ignored while this display correction is being made.
When the transmitter display is correct, press P
which will lock the transmitter display and, after
briefly displaying 'Ent', allow the 4/20mA output
current to be trimmed using the Up or Down push-
button. The output current should be measured
with an accurate DVM or another instrument within
the loop. Operate the Up or Down buttons until the
required output current is shown on the DVM or
other instrument. When correct, press the Ebutton
to store the trim correction in permanent memory
and return the BA574C transmitter to the 'ZEro'
prompt. This completes re-calibration of the
BA574Ctransmitter at minimum input.
The transmitter should now be re-calibrated at
maximum input by selecting the 'SPAn' sub-menu
and adjusting the calibrator to simulate maximum
input, or raising the primary element to maximum
temperature. With 'SPAn' displayed, pressing the
P push-button will cause the temperature display to
return. If the display does not correspond with the
input calibrator or the temperature of the primary
element, operate the Up or Down buttons until the
transmitter display is correct. Immediately the Up
or Down button is operated the annunicator in the
top left hand corner of the display will be activated
to warn that any changes in the input signal will be
ignored while this display correction is being made.
When the transmitter display is correct, press P
which will lock the transmitter display and, after
briefly displaying 'Ent', allow the 4/20mA output
current to be trimmed using the Up or Down push-
button. Again the output current should be
measured with an accurate DVM or another instru-
ment within the loop. Operate the Up or Down
buttons until the required output current is shown on
the DVM or other instrument. When correct, press
the Ebutton to store the trim correction in perma-
nent memory and return the BA574C transmitter to
the 'SPAn' prompt. This completes re-calibration
of the BA574C transmitter at maximum input.
When calibrating the BA574C using the Trim Menu
both the zero and span must be adjusted.
The Trim Menu contains a clear function which
enables the small calibration correction made with
the 'ZEro' and 'SPAn' sub-menus to be removed.
To clear the corrections select 'CLr' from the trim
menu and press P. The display will show 'Ent' for a
short while and then return to the'CLr' prompt.
6.2 Periodic re-calibration using Trim Menu
The Trim Menu is the best way of making small
calibration adjustments to compensate for any long
term drift which may occur. Initially an annual
check is recommended to achieve maximum
accuracy, although less frequent checks will usually
produce acceptable results.
If the BA574C internal references are used to make
frequent calibration changes, we recommend that
these references should be initially checked once
per year as described in sections 5.8.1 to 5.8.5 If
the BA574C is always calibrated with an external
reference, such as a voltage source using the Trim
Menu, it will not be necessary to check the internal
reference.
7. CALIBRATION EXAMPLE
In this example a BA574C is required to display
with maximum resolution the temperature of a type
J thermocouple, and to transmit a 4/20mA signal
representing -10 to 240oC. If the thermocouple
breaks the 4/20mA output current is to rise to full
scale. The current security code is 1209.
The example is divided into two sections. Steps 1
to 10 explain how to conditionthe transmitter and to
calibrate the 4/20mA output using the internal
references. This will produce acceptable accuracy
for most applications, but will not compensate for
errors in the thermocouple or load connected to the
4/20mA output. Steps 11 to 13 describe how the
Trim Menu may be used to calibrate the complete
loop and to compensate for thermocouple errors.
Step 1 Initialisation
When power is applied to the loop the
BA574Cwill automatically perform the
initialisationroutine described in section
2, and then display and transmit the
thermocouple temperature using the
existing calibration information.
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Step 2 Enter the ProgrammeMenu
Enter the Programme Menu by
simultaneously pressing the P and E
buttons. The transmitter will respond by
displaying 'COdE'. Press Pto clear this
prompt and set the display to the
security code 1209 using the Up, Down
and Ppush-buttons. Pressing Ewill
enter the code. After a few seconds
during which all the decimal points will
be activated, the first parameter 'InPut'
will be displayed.
Step 3 Define input
With 'InPut' displayed press Pwhich
will reveal the current transmitter sensor
type. Using the Up or Down button
scroll through the menu until
thermocouple input'tHC' is displayed.
Step 4 Define type of thermocouple
With 'tHC' displayed press Pto enter
the thermocouple sub-menu. The first
parameter 'tYPE' will be displayed,
pressing P again will give access to the
seven different types of thermocouple.
Select 'J' using the Up or Down button
and then press Eto return to the
sub-menu.
Step 5 Define units of display
Using the Up or Down button select
'dEg', from the sub-menu and press P
to reveal the current units. Pressing the
Up or Down button will toggle between
oC and oF. Select oC and press Eto
return to the sub-menu.
Step 6 Resolution
Using the Up or Down button select
'rESn' from the sub-menu and press P.
Pressing the Up or Down button will
toggle between high and low resolution,
select 'Hi' and press E to return to the
sub-menu.
Step 7 Cold junction compensation
In this example only one thermocouple
is connected so cold junction
compensation is required. Using the Up
or Down button select 'CJC' from the
sub-menu and press P. The Up and
Down buttons will turn the cold junction
'On' or 'OFF'. Select 'On' and press E
to return to the sub-menu.
Step 8 Input open circuit drive
Using the Up or Down button select
'burn' from the sub-menu and press P to
reveal the current status. Select 'uP'
using the Up or Down button and press
Ethree times to return to the 'InPut'
prompt via the 'burn' and'tHC' prompts.
Step 9 Calibrating the 4/20mAoutput
'CAL' defines the display at which the
output current is 4mA and 20mA.
Select 'CAL' from the menu using the
Up or Down push-button, and enter the
sub-menu by pushing P. The
transmitter will display a 'ZEro' prompt
requesting the display at which the
output is to be 4mA. Press P and
enter -10.0 using the Up, Down and P
buttons. Press Eto return to the 'ZEro'
prompt. Select 'SPAn' from the
sub-menu and press P. Enter 240.0
which is the display at which the output
current is to be 20mA and press E
twice to return to the 'CAL' prompt.
Step 10 Return to the display mode
With the 'CAL' prompt displayed, press
Eto store the conditioning and
calibration information and return to the
display mode. All the display decimal
points will be activated while the
information is being stored. This
completes the calibration of the
transmitter using the internal
references.
The following steps explain how, using the Trim
Menu, the BA574C transmitter may be calibrated
against an external reference, such as a voltage
source or temperature calibrator. Alternatively, the
complete loop including the primary element may
be calibrated by cooling and heating the
thermocouple to -10 and+240oC.
Step 11 Entering the Trim Menu
Enter the trim menu by simultaneously
pressing the Pand Down buttons - see
Fig 7. The transmitter will respond by
displaying 'COdE' . Press Pto clear
this prompt and set the display to the
security code 1209 using the Up, Down
and Ppush-buttons. Pressing Ewill
enter the code. After a few seconds
during which all the decimal points will
be activated, the first parameter 'ZEro'
will be displayed.
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Step 12 Zero adjustment
This adjustment trims the display to
read exactly -10.0oC and the output
current to be exactly 4.000mA when the
type J thermocouple is at -10oC. This
can be achieved by cooling the
thermocouple to -10oC or by inputting
the voltage which the thermocouple
should theoretically produce. If a
voltage is used the transmitter cold
junction compensation (see section
5.3.4) should be turned off during the
calibration, or the input voltage should
be corrected for ambient temperature,
although this may be less accurate.
With the transmitter displaying the
'ZEro' prompt and the correct input
connected to the transmitter, push P
which will cause the transmitter to
display the thermocouple temperature.
Adjust the display with the Up and
Down buttons until it is -10.0
Note: Immediately the Up or Down
button is operated the annunicator in the
top left hand corner of the display will
be activated to warn that any change in
the input signal will be ignored while this
display correction is being made.
Operating the P push-button will lock
the transmitter display at -10.0 and
allow the output current to be trimmed
using the Up or Down button. When the
output current measured by a DVM is
4.000mA, the Epush-button should be
operated to return the transmitter to the
'ZEro' prompt.
This completes calibration at-10.0oC.
Step 13 Span adjustment
With the transmitter displaying the
'ZEro' prompt select 'SPAn' by pressing
the Up or Down button. With the
thermocouple heated to 240oC, or an
equivalent voltage input, push Pwhich
will cause the transmitter to display the
thermocouple temperature. Adjust the
display with the Up and Down buttons
until it is 240.0
Note: Immediately the Up or Down
button is operated the annunicator in the
top left hand corner of the display will
be activated to warn that any change in
the input signal will be ignored while this
display correction is being made.
Operating the P push-button will lock
the transmitter display at 240.0 and
allow the output current to be trimmed
using the Up or Down button. When the
output current measured by a DVM is
20.000mA, the Epush-button should be
operated to return the transmitter to the
'SPAn'prompt.
This completes calibration at 240.0oC.
Pressing the E push-button again will
return the transmitter to the display
mode.
8. MAINTENANCE
8.1 Fault finding during commissioning
If the BA574C transmitter fails to function during
commissioning the following procedure should be
followed:
Symptom Cause Solution
No display Incorrect Check wiring
or output wiring or no and power
current power supply supply polarity
Check that voltage
between terminals
5 & 6 is between 10
and 30V with terminal
5 positive.
BA574C Positive The transmitter input
displays 1 display exceeds the upper
over-range operating range of the
selected THC or RTD.
For voltage inputs,
display is incorrectly
calibrated.
Check calibration.
BA574C Negative The transmitter input
displays -1 display is less than the lower
over-range operating range of the
selected THC or RTD.
For voltage inputs,
display is incorrectly
calibrated.
Check calibration.
Output fixed 4/20mAoutput The transmitter output
below 4mA current over, current is incorrectly
or above or under-range calibrated.
20mA. Check calibration.
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8.2 Fault finding after commissioning
ENSURE PLANT SAFETY BEFORE
STARTING MAINTENANCE
If a BA574C fails after it has been functioning
correctly the procedure shown in section 8.1 should
be followed.
8.3 Servicing
The BA574C uses surface mount components and
cannot be serviced on-site. Electronic assemblies
may be exchanged between enclosures, but
sub-boards must not be interchanged between
electronic assemblies. All BA574C transmitter
functions are easily programmable on-site, a single
spare transmitter or electronic assembly may
therefore be used to replace any instrument which
fails.
We recommend that suspect instruments are
returned to BEKA associates or our local agent for
repair.
8.4 Guarantee
Transmitters which fail within the guarantee period
should be returned to BEKA associates or our local
agent. It is helpful if a brief description of the fault
symptoms and a list of error messages is provided.
8.5 Customer comments
BEKA associates is always pleased to receive
comments from customers about our products and
services. All communications are acknowledged
and whenever possible, suggestions are
implemented.
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