BEKA BA578C, Руководство пользователя

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5.8.1 Conditioning internal references: 'Cond'
WARNING!
Adjusting the internal references will alter
the instrument performance. Do not
attempt to recalibrate these references
unless you have adequate test equipment
and have read the following instructions.
For routine calibration of 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 P button 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
E will then give access
to the sub-menu containing the four refences.
5.8.2 Voltage input reference 'U.IP'
With the BA578C 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. Adjust the external
voltage calibrator to supply -75.00mV and press
P
to 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 ac75.000mV input. When the input is
correct press
P to 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. It is preferable to make this
substitution as close to the RTD as possible, but
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. 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 a 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 P will 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.
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