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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' and '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

E

 three times to return to the 'InPut'

prompt via the 'burn' and 'tHC' prompts.

Step 9

Calibrating the 4/20mA output 

'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 

 and  

enter -10.0 using the 

Up

Down

 and 

P

buttons. Press 

E

 to 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

E

 to 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 BA578C 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 +240

o

C. This is the

preferred method for routine calibration.

Step 11 Entering the trim menu

Enter the trim menu by simultaneously
pressing the

 P

 and 

Down

 buttons - see

Fig 9. The transmitter will respond by
displaying 'COde' .  Press 

P

 to clear

this prompt and set the display to the
security code 1209 using the 

Up

Down

and 

P

 push-buttons.  Pressing 

E

 will

enter the code.  After a few seconds
during which all the decimal points will
be activated, the first parameter 'ZEro'
will be displayed.

Step 12 Zero adjustment

This adjustment trims the display to
read exactly -10.0

o

C and the output

current to be exactly 4.000mA when the
type J  thermocouple is at  -10

o

C.  This

can be achieved by cooling the
thermocouple to  -10

o

C or by inputting

the voltage which the thermocouple
should theoretically produce.  If a
voltage is used the transmitter cold
junction compensation (see section
6.3.4) 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  

 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 

E

 push-button should be

operated to return the transmitter to the
'ZEro' prompt.
This completes calibration at -10.0

o

C.

      17

Содержание BA578C

Страница 1: ...Issue 4 26th September 2008 BA578C panel mounting indicating temperature transmitter issue 4...

Страница 2: ...eferences 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 procedur...

Страница 3: ...ions of Section 5 you will find information on setting up for Section 6 3 Themocouple input Section 6 4 Resistance thermometer input Section 6 5 Voltage input A word of warning Section 5 8 explains ho...

Страница 4: ...the 4 20mA output current The transmitter and the optional alarms are powered from the 4 20mA current loop but the optional display backlight requires a separate supply Each time power is applied to...

Страница 5: ...sed in a robust aluminium enclosure with a polyester front panel and Noryl bezel The front panel provides IP65 protection and a gasket seals the joint between the instrument and the panel The transmit...

Страница 6: ...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...

Страница 7: ...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 wit...

Страница 8: ...8...

Страница 9: ...9...

Страница 10: ...st 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 the programme and trim menus See se...

Страница 11: ...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...

Страница 12: ...xt digit When the least significant digit has been adjusted press E to return to the dISP prompt 5 5 3 High input display calibration In HI This function defines the higher voltage input and the corre...

Страница 13: ...ned to the display mode If the security code is lost access to the Programme and Trim Menus can be obtained by putting the internal security link in the override position see Fig 6 The security code c...

Страница 14: ...mitters 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...

Страница 15: ...ly 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 mi...

Страница 16: ...se to full scale The current security code is 1209 The example is divided into two sections Steps 1 to 10 explain how to condition the transmitter and to calibrate the 4 20mA output using the internal...

Страница 17: ...may be calibrated by cooling and heating the thermocouple to 10 and 240o C This is the preferred method for routine calibration Step 11 Entering the trim menu Enter the trim menu by simultaneously pr...

Страница 18: ...display mode 8 MAINTENANCE 8 1 Fault finding during commissioning If the BA578C transmitter fails to function during commissioning the following procedure should be followed Symptom Cause Solution No...

Страница 19: ...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...

Страница 20: ...with a thermally printed tag strip on the rear panel with any legend containing up to 35 alphanumeric characters This strip is not visible from the front of the instrument after installation 10 ALARM...

Страница 21: ...alarm parameters See section 10 3 1 SP1 Alarm setpoint 1 Adjusts the alarm setpoint The alarm is activated when the indicator display equals the setpoint The setpoint can also be adjusted directly fro...

Страница 22: ...22 Fig 11 Programme structure for optional alarms...

Страница 23: ...ut status select no nc from the alarm sub menu and press P to reveal the current setting The function may be changed by pressing the Up or Down buttons followed by the E button to return the no nc pro...

Страница 24: ...AcSP prompt in the Programme Menu Code 0000 will disable the security code allowing direct access to the setpoints by pressing the P and Up buttons simultaneously New instruments are supplied with thi...

Страница 25: ...installed in a poorly illuminated area The backlight is segregated from the measuring circuit and may be powered from any 18 to 30V dc supply Fig 13 Backlight power supply The brilliance of the displ...

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