Transferring Controller From One Actuator To Another; Unison Control; Manual Minimum Positioning Of Outdoor Air Damper - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

THERMOSTAT
DPDT
W R
SWITCH,
RELAY, OR
THERMOSTAT
HEATING
COOLING
W R
ACTUATOR
Fig. 30. Circuit Used for Reversing
Heating and Cooling Control.
Transferring Controller from
One Actuator to Another
Figure 31 illustrates a circuit which allows a single controller
to control two Series 90 actuators, one at a time. With the 3pdt
switch in the Cooling (C) position, the circuit connects the
controller to the cooling actuator with B to W and W to B. The
cooling actuator operates under normal control of the controller.
At the same time, the manual switch causes R to W to connect
at the heating actuator, positively closing it. With the switch in
the Heating (H) position, the controller is connected B to B
and W to W to the heating actuator which operates normally
and the cooling actuator is positively closed by a R to W
connection at the actuator.
CONTROLLER
W R B
SPDT SWITCH
H
C
TRANSFORMER
W R B
T1
LINE
VOLTAGE
T2
HEATING
ACTUATOR
Fig. 31. Circuit for Transferring Controller
from One Actuator to Another.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
B
TRANSFORMER
B
T1 LINE
VOLTAGE
T2
C2531
TRANSFORMER
W R B
T1
LINE
VOLTAGE
T2
COOLING
ACTUATOR
ELECTRIC CONTROL FUNDAMENTALS

UNISON CONTROL

Figure 32 illustrates a circuit for controlling up to six
Series 90 actuators in unison from one Series 90 controller.
The B to W terminals of the controller are shunted with the
appropriate value resistor, depending on the number of
actuators in the circuit. This method can control a large bank
of dampers requiring more torque than can be provided from
a single actuator.
W R B W
T1
T2
ACTUATOR ACTUATOR
Fig. 32. Actuators Controlled in
Unison from One Controller.
MANUAL MINIMUM POSITIONING
OF OUTDOOR AIR DAMPER
Figure 33 illustrates a circuit for a typical outdoor air damper
control system with a manual potentiometer for minimum
positioning. Adjusting the potentiometer so that the wiper is at
W shorts the potentiometer coil out of the circuit and the outdoor
air damper actuator operates normally. The damper closes
completely if commanded by the controller. Moving the
potentiometer wiper toward B increases the resistance between
B on the controller and W on the actuator to limit the travel of
the actuator toward closed. The damper remains at the set
minimum position even though the controller is trying to close
it completely.
MINIMUM POSITION
POTENTIOMETER
135
W R B
C2532
DAMPER
Fig. 33. Manual Minimum Positioning
of Outdoor Air Damper.
113
CONTROLLER
W R B
SHUNTING
RESISTOR
TRANSFORMER
R B W R B
T1 T1
T2 T2
ACTUATOR
CONTROLLER
135
B R W
W R B TRANSFORMER
T2
LINE
VOLTAGE
T1
ACTUATOR
LINE
VOLTAGE
C2533
C2534