Operating instructions

68
Dual Chiller Sequence of Operation — With a com-
mand to start the chiller, the master chiller determines which
chiller will become the lead chiller based on the configuration
of Lead Lag Select, LLBL and Lead/Lag Balance Data,
LLBD. The lead chiller is always started first and the lag chiller
is held at zero percent capacity by the master chiller forcing the
lag demand limit value to 0%. If Lead Pulldown Time (Lead
Pulldown Time, LPUL) has been configured, the lead chiller
will continue to operate alone for that specified time. After the
Lead Pulldown Time timer has elapsed and when the lead chill-
er is fully loaded, either all available compression is on or at the
master demand limit value, then the lag start timer (Lag Start
Timer, LLDY) is initiated. When the pulldown timer and lag
start timer has elapsed and the Combined Leaving Chilled Wa-
ter Temperature is more than 3° F (1.7° C) above the set point,
then the lag chiller is started. If the lag chiller’s water pump
was not started when the machines went into occupied mode,
the lag chiller water pump will be started. The lag chiller will
start with the master chiller forcing the lag chiller demand limit
value (LAG_LIM) to the master’s demand limit value. If lead/
lag capacity balance is selected, once the lag chiller has started,
the master shall try to keep the difference in capacity between
lead and lag less than 20%. The master shall then be responsi-
ble for water loop capacity calculation, and will determine
which chiller, the lead or lag, will increase or decrease capacity.
When the load reduces, the lag chiller will be the first chiller to
unload. To accomplish this, the lead chiller set point is de-
creased by 4° F (–2.2° C) until the lag chiller unloads.
PUMP OPERATION — For parallel chiller pump operation,
the lead chiller’s water pump will be started. The lag chiller’s
water pump will be maintained off if Lag Unit Pump Control,
LAGP=0. The internal algorithm of lead chiller will control ca-
pacity of the lead chiller.
For series chiller operation, the pump is always controlled
by the master chiller.
Operating Modes — Operating modes are override
modes that affect normal operation of the equipment. More
than one operating mode can be in effect at the same time.
Some operating modes have corresponding capacity control
overrides in the Capacity Control Overrides section on
page 47.
For the Touch Pilot™ display, the status of the operating
modes can be found in the MODES submenu, which is under
the STATUS menu. Each operating mode and its status (Yes =
active, No = inactive) is listed.
For the Navigator™ display, the status of the operating
modes can be found in the MODE submenu under the OPER-
ATING MODES menu. The 6 top priority operating modes are
displayed in MD01 through MD06. To view the modes with
the Navigator display:
See Table 45 for a list of operating modes.
STARTUP DELAY IN EFFECT — This mode is checked
for when the unit is started. This mode is active when the Min-
utes Off Time (Unit Off to On Delay, DELY) timer is active.
The unit will not start until the timer has expired. The mode
will terminate when the timer expires.
BASE PLATE
VALVE MOTOR
VALVE MOTOR COVER
VALVE SHAFT
CLAMPING SCREW
ACTUATOR ARM
DISENGAGEMENT
BUTTON
MOUNTING - FULLY CLOSED
MOUNTING - FULLY OPEN
Fig. 39 — Typical ABV Assembly with Enclosure
Fig. 40 — Fully Open Ball Valve
with Actuator Removed
Fig. 41 — Ball Valve Motor
a30-4236
a30-4237
a30-4238
ITEM ITEM EXPANSION PATH VALUE
MD01 First Active Mode Operating modes
MODE 0-32
MD02 Second Active Mode Operating modes
MODE 0-32
MD03 Third Active Mode Operating modes
MODE 0-32
MD04 Fourth Active Mode Operating modes
MODE 0-32
MD05 Fifth Active Mode Operating modes
MODE 0-32
MD06 Sixth Active Mode Operating modes
MODE 0-32