Commissioning; Analogue And Hart Communication Models; Standard Setting For Normal Operation 3.8 Ma / 20.5 Ma; Standard Setting For Error Detection (Alarm) 3.7 Ma / 21 Ma - ABB 266 HART Series Operating Instruction

7 Commissioning

Once the transmitter has been installed, it is put into operation
by switching on the operating voltage.
Check the following before switching on the operating voltage:
— Process connections
— Electrical connection
— The impulse line/s and the measuring chamber of the
measuring equipment must be completely filled with the
measuring medium.
The transmitter can then be put into operation. To do this, the
shut-off valves must be actuated in the following sequence (in
the default setting, all valves are closed).
(Differential models) 266Dxx or 266Mxx
— Open the shut-off valves on the pressure tap connection.
— Open the pressure equalization valve of the manifold.
— Open the positive shut-off valve (on the manifold).
— Open the negative shut-off valve (on the manifold).
— Close the pressure equalization valve.
To put the transmitter out of operation, carry out the steps in
reverse order.
(Gauge & Absolute models) 266Gxx, 266Axx, 266Hxx,
266Nxx, 266Pxx, 266Vxx, 266Rxx
— Open the shut-off valve on the pressure tap connection.
— Open the positive shut-off valve.
To put the transmitter out of operation, carry out the steps in
reverse order.
Important. For the absolute pressure transmitters model 266ASx,
266NSx, 266RSx or 266VSx with sensor range C, F or G, please be
aware that the measuring equipment will have been overloaded by
the atmospheric pressure due to the long periods of transport and
storage involved.
For this reason, you will need to allow a starting time of approx. 30
minutes for 266Vxx, 266Rxx and 266Nxx models and approx. 3
hours for 266Axx models after commissioning, until the sensor has
stabilized to such an extent that the specified accuracy can be
maintained.
If, when using "intrinsically safe" transmitters, an ammeter is
connected to the output circuit or a modem is connected in parallel
while there is a risk of explosion, the sums of the capacitances and
inductances of all circuits, including the transmitter (see EC-type-
examination certificate) must be equal to or less than the
permissible capacitances and inductances of the intrinsically safe
signal circuit (see EC-type-examination certificate for the supply
unit).
Only passive or explosion-proof devices or indicators may be
connected. If the output signal stabilizes only slowly, it is likely that
a large damping time constant has been set on the transmitter.
32 OI/266/HART-EN Rev. M | 2600T Series Pressure transmitters

7.1 Analogue and HART Communication models

If the pressure applied falls within the values indicated on the
name plate, the output current will be between 4 and 20 mA.
If the pressure applied falls outside the set range, the output
current will be between 3.5 mA and 4 mA if the range is
undershot or between 20 mA and 22.5 mA if the range is
overshot (depending on the respective configuration).
7.2 Standard setting for normal operation
3.8 mA / 20.5 mA
In order to prevent errors in flow rate measurements (266Dxx
and 266Mxx) in the lower range, it is possible to set a "cut off
point" and/or a "lin./sq. root transition point" via the optional
LCD integral displays with keypad or via the graphical user
interface (DTM).
Unless otherwise specified, the "lin./sq. root transition point" is
set to 5% and the "cutoff" to 6% of the flow rate end value by
the manufacturer; A current that is < 4 mA or > 20 mA may
also indicate that the microprocessor has detected an internal
error. In this case the alarm output can be configured both via
the local LCD with keypad, via an external Hart hand held
terminal (ABB DHH805) or via a DTM based configuration tool
(Asset Vision).
7.3 Standard setting for error detection (alarm)
3.7 mA / 21 mA
The graphical user interface (DTM) or the LCD integral display
(if installed) can be used to diagnose the error.
Important. A brief interruption in the power supply results in
initialization of the electronics (program restarts).
Important. Alarm current
— Lower limit: 3.6 mA (configurable from 3.6 to 4 mA)
— Upper limit: 21 mA (configurable from 20 to 23 mA, limited to
22 mA for HART Safety; apply for electronics release 7.1.15 or
later)
Factory setting: high alarm current (21.0 mA)

7.4 Write Protection

Write protection prevents the configuration data from being
overwritten by unauthorized users.
If write protection is enabled, the "Z" and "S" buttons (both
internal or external) are disabled. However, it is still possible to
read out the configuration data using the graphical user
interface (DTM) or another, similar communication tool. The
control unit may be leaded if required.

7.4.1 Write protection activation via external push button

When the instrument features the external non-intrusive push
buttons (digit R1 within instrument code), the write protection
function can be performed as follows:
— Remove the identification plate (see figure 3 at chapter 4)
by releasing the holding screw lying on the bottom left
corner.
— Use a suitable screwdriver to press the switch down fully.
— Then turn the switch clockwise by 90°.
Important. To deactivate the switch, push it down slightly and then
turn counterclockwise by 90°.
7 Commissioning