|
APPLICATIONS
The T630 is designed for control of standard process variables —
Temperature, Flow, Pressure, etc — in applications such as
industrial boilers, furnaces, kilns, reactors and mixing vessels;
in fact any application where high integrity process control is
required.
The communications options make the T630 ideally
suited for frontend PID control where the logic and coordination
is carried out in a DCS or PLC.
Single loop control
A simple single loop process controller algorithm can be achieved
with the basic I/O board only. Use of a hardwired remote setpoint
requires the Expansion I/O board, which also provides the necessary
analogue and digital I/O for interlocking between separate master
and slave units so as to assure bumpless transfers. Alternatively
the setpoint trim input allows offset of the process variable in
furnace applications etc.
Incremental output
For single loop, dual loop cascade and ratio control, incremental
(raise/lower) outputs for the control of fixed speed bi-directional
motors are available. The algorithm provides raise and lower output
pulses and compensation for both motor inertia and backlash. Position
feedback display is available if required. The expansion I/O card
is required and outputs are allocated as shown.
Override control
Override control allows a secondary loop to take over the main control
output in order to prevent an undesirable operating condition, for
example in flow control with pressure override. The two PID algorithms
drive a single control output via a low signal selector.
ALARM HANDLING
The basic controller has both a watchdog relay output and a relay
for process alarms. Use of the Expansion I/O board provides additional
high and low alarm outputs. Process alarms are indicated by flashing
of the loop 1 and loop 2 alarm LEDs on the front panel. Unacknowledged
absolute and deviation alarms cause flashing of the PV and SP bargraphs
respectively. Alarms may be acknowledged by pushbutton for the current
loop, and the alarm acknowledge status is also accessible via the
communications.
|
|
CONTROL CONFIGURATIONS
The basic input/output set allows for a single process input (with
integral transmitter supply) and a single process output, both isolated.
Two relays are provided for watchdog and process alarm. An expansion
I/O card provides a second process input with transmitter PSU, a
further analogue input and one analogue output. These may be connected
in various ways to the available internal parameters such as remote
setpoint, track, retransmitted process variable etc. More flexibility
is provided by four digital inputs and four digital outputs which
may be connected to mode enable and alarm/status fields respectively.
All such parameters and status fields may be modified from the front
panel or a supervisory computer when not connected to the I/O terminals.
Ratio control
The ratio controller implementation allows the controlled variable
to follow an external input at a set ratio. The ratio setpoint and
control PV are viewed in loop 1 while the ratio PV and the setpoint
in engineering terms may be viewed in loop 2.
Dual loop cascade control
A classical two loop cascade pair with full bumpless, procedureless
auto/manual/remote switching. All necessary interlocks are made
internally so that wiring and configuration are very simple.
Manual station
The Manual Station acts as the output device to an externally implemented
control loop or simply as a manual loader. When used with an external
control signal, the unit may be switched into local manual either
by the operator or, automatically on failure of the external system.
 |
