Carbolite TZF Series - Manual (Page 6)

STF/TZF
6
MF08 – 3.24
3.3 3-zone Control Methods
Applicable to TZF only.
The TZF is designed to achieve an extended uniform temperature zone by the use of three control
zones. The control zones are typically linked so that they are all follow the central controller in a
master-slave approach; there are two ways of doing this. Alternatively independent control zones
may be ordered. There are thus three control methods (A, B & C).
A. Back-to-Back Thermocouples
This is the most commonly supplied option.
The central zone is controlled directly by the central temperature controller. Each end zone
thermocouple is wired in opposition to a central reference thermocouple, and the small voltage
resulting when the zones are at different temperatures is used by the end zone controller. The
circuit diagram in section 7.6 shows the thermocouple arrangement.
Set the "setpoint" of the end zone controllers to zero. To alter the setpoint (with the display at
“home”), press Down  or Up  once to display the setpoint; press again or hold down to adjust
it. The display returns to the measured temperature offset when no key is pressed for 0.5 seconds.
Sometimes a furnace using this type of control does not cool down: the end controllers try to
remain at the central temperature. Should this occur, contact Carbolite’s technical department.
2132 Slave Controller Navigation Diagram
B. Retransmission of Setpoint using Broadcast Comms
When this is ordered there are three independent thermocouples connected to the three controllers.
The controllers are linked together, the central controller communicating the desired setpoint to the
end controllers.
Additional communication modules are fitted in the controllers, rather than an additional
thermocouple as in A. The communication between the controllers of the Eurotherm 3000 series is
known as Broadcast comms. The wiring connections between the controllers are shown in section
7.7.
It is possible to switch off the linked control and allow the controllers to work independently. In
level 2 of the end zone controllers (see controller operating instruction), scroll to
L-r. Where the
end zone controller is a 3216 use the  up  down and select NO . Where the end zone controller
is a 3508 use the  up  down to select SP1, (SP1 = Local, and SP2 = Remote). There is no
need to alter the centre controller.
It is possible to use local trim in the end zone controllers to enter a positive or negative adjustment
from the centre zone temperature. Once entered this trim will always be added or subtracted from
the retransmitted set temperature. In level 2 of the end zone controller (see controller operating
instruction), scroll to
LOC.T (local trim) and use the  up  down enter the desired positive or
negative difference to be added to the end zone set temperature. There is no need to alter the
centre controller.
Home
List
Access
List
°C/F/k ACCS
°C/F/k codE
0.0
Zone temperature
difference; use

/

to
access offset “setpoint”
home list
for factory access to lists
and parameters not
available to the operator


OP.Hi
Output
List
oP

power limit
setting