BEKA BA574C, Руководство пользователя, Страница: 12 / 26

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
P which 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 P will 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 P will
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 P again 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 E to
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
P to reveal the current setting. The setting
may be changed by pressing the Up or Down
button. When the required units is displayed, press
E to 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
o
C. When
o
F
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 E to return to
the sub-menu.
Display Resolution
Type Low (Lo) High (Hi)
E 1
o
C 0.1
o
C
J 1
o
C 0.1
o
C
K 1
o
C 0.2
o
C *
N 1
o
C 0.2
o
C *
R 1
o
C 0.4
o
C *
T 1
o
C 0.1
o
C
Pallaplat 1
o
C 0.2
o
C *
* 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
P to
reveal the current status. The setting may be
changed by pressing the
Up or Down button. When
set as required press E to 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
P to
reveal the current setting. The setting may be
changed by pressing the
Up or Down button. When
the required setting has been selected, press E to
return to the sub-menu.
12