09Az Air-Cooled Condensers; Operation Sequence; Variable Speed Fan Control; Adjusting Pid Routines - Carrier ComfortLink 6 Series Controls, Start-Up, Operation, Service, And Troubleshooting

The 09DK054-094 condensers are supplied with fan cycling
pressure switches suitable for use with R-22 refrigerant. Fan
cycling pressure switches that are compatible with R-134a
refrigerant pressures are shipped with the 30HXA chillers.
These fan cycling pressure switches must be installed in place
of the 09DK factory-installed switches before charging to
ensure proper head pressure control.
The air temperature switch controls the fans as follows: On
the 074-094 condensers, below 70 ± 3 F (21.1 ± 1.7 C) outdoor
ambient, fans 5 and 6 are off; above 80 ± 3 F (26.7 ± 1.7 C) fans
5 and 6 are on. Between 70 F (21.1 C) and 80 F (26.7 C), wheth-
er fans 5 and 6 are on or off depends on whether temperature is
rising or falling. If the temperature is rising from 70 F (21.1 C)
to 80 F (26.7 C), fans 5 and 6 are off. If the temperature is fall-
ing from 80 F (26.7 C) to 70 F (21.1 C), fans 5 and 6 are on.
09AZ AIR-COOLED CONDENSERS — The 09AZV091-
182 units are designed to operate specifically with 30HXA
chillers, using R-134a refrigerant. Units with 8 fans have
2 direct controlled (applied to optional variable speed), 4 refrig-
erant pressure and 2 ambient temperature controlled fans. Units
with 10 fans have 2 direct controlled (applied to optional vari-
able speed), 4 refrigerant pressure and 4 ambient temperature
controlled fans. Units with 12 fans have 2 direct controlled
(applied to optional variable speed), 6 refrigerant pressure and
4 ambient temperature controlled fans. Field adjust 09AZ
switch settings as follows:
PRESSURE
Cut in 175 psi
Cut out 145 psi
OPERATION SEQUENCE — All condenser fans are al-
lowed to operate once a call for cooling comes from the chiller.
Direct fans will operate while refrigerant pressure and ambient
temperature control fans maintain refrigerant head pressure
based on existing refrigerant pressure and ambient temperature
conditions. Optional variable speed control will ramp direct fan
motor speed for improved low ambient performance.
VARIABLE SPEED FAN CONTROL — All units, when
ordered with fan head pressure control are furnished with the
number 1 condenser motor as a single-phase motor for use
with head pressure control. The optional factory-mounted
motor head pressure control contains a fan head pressure
control device activated by a pressure sensor. The kit controls
condenser-fan motor speed in response to the saturated
condensing pressure.
ADJUSTING PID ROUTINES — The 30GXN,R, 30HXA
and 30HXC head pressure control routines use PID (propor-
tional integral derivative) loops to maintain a user-configurable
head pressure set point. Gain defaults values are located in the
SERV sub-mode under the Configuration mode (items H.PGN,
H.IGN and H.DGN). The control calculates a new fan speed
(30GXN,R) or water valve position (30HXC) every 5 seconds
based on these gain values and an error term equal to saturated
condensing temperature minus head pressure set point. If the
control routine is not responding fast enough to large changes
(circuit starting, for example), increase the proportional term.
When the routine is making too great a change to valve posi-
tion or fan speed, decrease the proportional term. To minimize
hunting, keep the integral term positive and as low as possible.
This value is used to control "droop," which is common in
master/submaster control schemes. The default for the deriva-
tive term is zero. The value should not need to be changed.
For more information on tuning PID loops, consult
the Comfort Controller Installation manual, catalog number
808-890. Follow the instructions under Tuning Control loops.

Control Methods

SWITCH — Unit is started and stopped manually by switch-
ing the ENABLE/OFF/REMOTE CONTACT switch from
OFF to ENABLE or by external contacts with the switch in the
AMBIENT
Cut in 70 F
Cut out 60 F
17
REMOTE position. The unit can be enabled and disabled by
this action or all control methods.
7-DAY SCHEDULE — Unit is started and stopped in accor-
dance with the schedule configured under Time Clock mode.
This schedule can be configured from the Navigator or from

CCN.

OCCUPANCY — Unit is started and stopped in accordance
with the local occupancy schedule accessible only from CCN.
Schedule Number in Table SCHEDOVR must be configured
to 1 to utilize the local occupancy schedule, or 65-99 to utilize
a global schedule. If the Schedule Number is set to 0 the unit
will operate in a continuous 24-hr Occupied mode.
CCN — Unit is started and stopped by communication over
the CCN bus. The CHIL_S_S point in the A_UNIT table is
provided for this purpose.
Table 8 illustrates how the control method and cooling
setpoint select variables direct the operation of the chiller and
the set point to which it controls. The illustration also shows
the ON/OFF state of the machine for the given combinations.
Cooling Set Point Select
SINGLE — Unit operation is based on Cooling Setpoint 1
(CSP1).
DUAL SWITCH — Unit operation is based on Cooling
Setpoint 1 (CSP.1) when the Dual Setpoint switch contacts are
open and Cooling Setpoint 2 (CSP.2) when they are closed.
DUAL 7 DAY — Unit operation is based on Cooling Setpoint
1 (CSP.1) during the occupied mode and Cool Setpoint 2
(CSP.2) during the unoccupied mode as configured under Time
Clock mode. Control method must be configured for Switch.
DUAL CCN OCCUPIED — Unit operation is based on
Cooling Setpoint 1 (CSP.1) during the Occupied mode and
Cooling Setpoint 2 (CSP.2) during the Unoccupied mode as
configured under the local occupancy schedule accessible only
from CCN. Schedule Number in Table SCHEDOVR must be
configured to 1. If the Schedule Number is set to 0 the unit will
operate in a continuous 24-hr Occupied mode. Control method
must be configured for Switch.
4 TO 20 mA INPUT — Unit operation is based on an exter-
nal 4 to 20 mA signal input to the Energy Management Module
(EMM).
Ice Mode —
When Ice Mode is enabled Cooling Setpoint
Select must be set to Dual Switch, Dual 7 day or Dual CCN
Occupied and the Energy Management Module (EMM) must
be installed. Unit operation is based on Cooling Setpoint 1
(CSP.1) during the Occupied mode, Ice Setpoint (CSP.3) dur-
ing the Unoccupied mode with the Ice Done contacts open and
Cooling Setpoint 2 (CSP.2) during the Unoccupied mode with
the Ice Done contacts closed. These 3 set points can be utilized
to develop your specific control strategy.
Cooler and Condenser (30HXC) Pump Con-
trol —
The 30GXN,R and 30HX chillers can be configured
for cooler and condenser (30HXC) pump control. Inputs for a
cooler pump interlock and condenser flow switch or interlock
are provided.
COOLER PUMP CONTROL (CPC, Configuration Mode/
sub-mode OPT1) — Proper configuration of the cooler pump
control is required to prevent possible cooler freeze-up. A
cooler flow switch is factory installed to prevent operation
without flow through the cooler. It is also recommended that
the chiller be interlocked with the chiller water pump starter to
provide additional protection. See page 72 of the Field Wiring
section for proper connection of the cooler pump interlock.
The factory default setting for cooler pump control is "OFF."
It is recommended for all chillers that the cooler pump control
be utilized unless the chilled water pump runs continuously or
the chilled water system contains a suitable antifreeze solution.