Control Combinations; Two-Position Control Of Steam Valve; Summer/Winter Changeover Control Of Athree-Way Diverting Valve; Open-Closed Control Of Damper - Honeywell AUTOMATIC CONTROL Engineering Manual

CONTROL COMBINATIONS

The following are representative Series 60 two-position
control circuits. Notice that many of these functions can be
done with Series 40 or 80 systems. If spring-return action is
required when power fails, use Series 40 or 80.

TWO-POSITION CONTROL OF STEAM VALVE

Figure 15 illustrates two-position control of a steam valve.
During the day when the temperature sensed by the Series 60
controller drops below the setpoint, contacts R to B close and
the actuator opens the valve allowing the steam to flow to the
coil. On a rise in temperature, contacts R to W close and the
actuator closes the valve stopping the flow of steam. At night
the time clock overrides the temperature controller and drives
the actuator/valve closed.
TEMPERATURE
TIME CLOCK
CONTROLLER
DAY
W
NIGHT
W
STEAM
Fig. 15. Series 60 Two-Position Control of Steam
Valve with Time clock Override.
SUMMER/WINTER CHANGEOVER CONTROL OF A
THREE-WAY DIVERTING VALVE
Figure 16 illustrates summer/winter changeover control of
a three-way diverting valve. A Series 60 controller senses
outdoor air temperature to determine when to change over
from heating to cooling. When the outdoor air temperature
drops below the setpoint of the controller, contacts R to W
open and R to B close calling for winter operation. The low-
limit controller, located in the return water line, senses the return-
water temperature. If the water temperature is above the setpoint
of the low limit controller, the R to B circuit completes, and the
actuator positions the diverting valve to send the return water
to the boiler. If the low-limit controller senses that the return
water is too cool, the contacts open, and the valve remains in a
position to divert the return water through the chiller. This circuit
protects the boiler from thermal shock by not allowing chilled
water into the hot boiler.
R B
VALVE
ACTUATOR
TRANSFORMER
R B
T2
LINE VOLTAGE
T1
TO
COIL
C2516-1
ELECTRIC CONTROL FUNDAMENTALS
HIGH-LIMIT
CONTROLLER
CAPILLARY
WATER
SENSING
ELEMENTS
Fig. 16. Series 60 Summer/Winter Changeover
Control of Diverting Valve.
When the outdoor air temperature rises above the setpoint
of the controller, contacts R to B open and R to W close
calling for summer operation. If the water temperature is
below the setting of the high limit, the R to W circuit
completes, and the actuator positions the diverting valve to
send the return water to the chiller. If the high-limit controller
senses that the return water is too warm, the contacts open,
and the valve remains in a position to divert the return water
through the boiler. This circuit protects the chiller by not
allowing hot water into the chiller.

OPEN-CLOSED CONTROL OF DAMPER

Figure 17 illustrates open-closed control of a damper. A
Series 60 actuator is linked to a ventilating damper. When the
controller senses that the temperature in the interior of the
building is above the controller setpoint, contacts R to B open
and R to W close. This powers the R to B actuator terminals
causing the actuator shaft to turn, opening the dampers. When
the controller senses that the temperature is below the setpoint,
contacts R to W open and R to B close causing the actuator
shaft to close the damper.
TEMPERATURE
CONTROLLER
DAMPER
B
W
ACTUATOR
Fig. 17. Series 60 Open-Closed Control of Damper.
105 ENGINEERING MANUAL OF AUTOMATION CONTROL
OUTDOOR
CONTROLLER
W R B
LOW-LIMIT
CONTROLLER
ACTUATOR
TRANSFORMER
W R B
T1
LINE
VOLTAGE
T2
TO BOILER
C2517
TO CHILLER
R W
TRANSFORMER
R B
T1
LINE
VOLTAGE
T2
C2518