Control Combinations; Two-Position Control Of Steam Valve; Summer/Winter Changeover Control Of A; Three-Way Diverting Valve - Honeywell AUTOMATIC CONTROL SI Edition 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.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
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
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