Specifications
60
PUMP PERIODIC START — This mode is active when the
cooler pump is started due to the Periodic Pump Start configu-
ration (Pump Sticking Protection, PM.PS=YES). If the pump
has not run that day, a pump will be started and will run for 2
seconds at 2:00 PM. If the machine is equipped with dual
pumps, Pump no. 1 will run on even days (such as day 2, 4, 6
of the month). Pump no. 2 will run on odd days (such as day 1,
3, 5 of the month). The mode will terminate when the pump
shuts down.
SYSTEM MANAGER ACTIVE — This mode is checked
when the unit is ON or OFF. This mode is active if a System
Manager such as Building Supervisor, Chillervisor System
Manager, or another CCN device is controlling the machine.
When this mode is active, the machine will respond to the
specific commands received from the System Manager. The
mode will be terminated if the System Manager control is
released.
MASTER SLAVE CONTROL ACTIVE — This mode is
checked for if the machine is ON. This mode is active if Master
Slave Control has been enabled. This occurs when two ma-
chines are programmed, one as the master (Master/Slave Se-
lect, MSSL=1 [Master]) and the other as a slave (Master/
Slave Select, MSSL=2 [Slave]).
Both the master and slave machines will respond to the ca-
pacity control commands issued by the master controller. This
may include control point changes and demand limit com-
mands. This mode will terminate when Master Slave Control
has been disabled.
AUTO CHANGEOVER ACTIVE — This mode is not
supported.
FREE COOLING ACTIVE — This mode is not supported.
RECLAIM ACTIVE — This mode is not supported.
ELECTRIC HEAT ACTIVE — This mode is not supported.
HEATING LOW EWT LOCKOUT — This mode is not sup-
ported.
CONDENSER PUMPS ROTATION — This mode is
checked for whether the unit is ON or OFF. The mode is active
when the condenser pump sequence (Condenser Pump
Sequence, HPUM = Yes) and the pump rotation delta timer
(Pump Auto Rotation Delay, ROT.P) have expired.
ICE MODE IN EFFECT — This mode is checked for when
the unit is ON. This mode is active when Ice Setpoint (Cooling
Ice Setpoint, CSP.3) is in use. While in this mode, the Active
Setpoint (Current Setpoint, SETP) will show the Cooling Ice
Setpoint, CSP.3 value and the unit will operate to the Ice Set-
point (CSP.3). This mode will terminate when the Ice Setpoint
(CSP.3) is no longer in use.
DEFROST ACTIVE ON CIR A — This mode is not supported.
DEFROST ACTIVE ON CIR B — This mode is not supported.
LOW SUCTION CIRCUIT A
LOW SUCTION CIRCUIT B
These modes are checked when the circuit is ON. The
appropriate circuit mode will be active if one of the follow-
ing conditions is true:
1. If the circuit’s saturated suction temperature (SST) is
more than 6° F (3.3° C) less than the freeze point and
both the cooler approach (Leaving Water Temperature –
SST) and superheat (Suction Gas Temperature – SST) are
greater than 15° F (8.3° C).
2. If the circuit is ON and the circuit’s SST is more than
18º F (10.0º C) below the freeze point for more than
90 seconds.
3. If the circuit’s saturated suction temperature is more
than 6° F (3.3° C) below the freeze point for more than
3 minutes.
For a fresh water system (Cooler Fluid Type, FLUD =1),
the freeze point is 34° F (1.1° C). For medium temperature
brine systems, (Cooler Fluid Type
, FLUD=2), the freeze point
is Brine Freeze Set Point (Brine Freeze Setpoint, LOSP).
For criterion 1, no additional capacity will be added. For cri-
teria 2 and 3 capacity will be decreased on the circuit. The
mode will terminate when the circuit’s SST is greater than the
freeze point minus 6° F (3.3° C) or the circuit has alarmed.
If this condition is encountered, see Possible Causes for
Alarms 56 and 57 on page 81.
HIGH DGT CIRCUIT A
HIGH DGT CIRCUIT B — The capacity of the affected
circuit may be increased to reduce circuit discharge gas
temperature.
HIGH PRES OVERRIDE CIR A
HIGH PRES OVERRIDE CIR B — This mode is checked
for when the circuit is ON. The appropriate circuit mode will
be active if the discharge pressure for the circuit, Discharge
Pressure Circuit A (Discharge Pressure, DP.A), Discharge
Pressure Circuit B (Discharge Pressure, DP.B), or Discharge
Pressure Circuit C (Discharge Pressure, DP.C), is greater than
the High Pressure Threshold (High Pressure Threshold,
HP.TH).
The capacity of the affected circuit will be reduced. Two
minutes following the capacity reduction, the circuit’s saturated
condensing temperature (SCT
t+2
) is calculated and stored. The
affected circuit will not be allowed to add capacity for at least 5
minutes following the capacity reduction. If after 5 minutes,
the circuit’s saturated condensing temperature is less than
SCT
t+2
–3° F (1.7° C), and then if required, percent capacity
will be added. If additional capacity is required, the control will
look for other circuits to add capacity.
This mode will terminate once the circuit’s saturated con-
densing temperature is less than SCT
t+2
–3° F (1.7° C).
If this condition is encountered, see Possible Causes for
Alarm A1.03. on page 86.
LOW SUPERHEAT CIRCUIT A
LOW SUPERHEAT CIRCUIT B — This mode is checked
for when the circuit is ON. The appropriate circuit mode will
be active if the circuit’s superheat (discharge gas temperature
— SCT) is less than 18° F (10° C).
No additional capacity will be added until the circuit’s su-
perheat is greater than 18° F (10° C). The control will look for
other circuits to add capacity if additional steps of capacity are
required. This mode will terminate once the affected circuit’s
superheat is greater than 18° F (10° C).
If this condition is encountered, see Possible Causes for
Alarms P.11 and P.12 on page 82.
Sensors — The electronic control uses up to 13 thermistors
to sense temperatures and up to 8 transducers to sense pressure
for controlling chiller operation. These sensors are outlined
below. See Fig. 44 for thermistor and transducer locations.
THERMISTORS (Tables 38-39B) — Thermistors that are
monitoring the chiller’s operation include: cooler entering wa-
ter, cooler leaving water, condenser entering water, condenser
leaving water, dual chiller leaving water, compressor suction gas
temperature, compressor discharge gas temperature, economiz-
er temperature, and compressor motor temperature. These
thermistors are 5 kat 77 F (25 C) and are identical in tempera-
ture versus resistance. The space temperature thermistor is 10
kat 77 F (25 C) and has a different temperature vs. resistance.
See Fig. 44 for thermistor locations.
Cooler Leaving Water Sensor
— On all sizes, this thermistor
is installed in a well in the leaving water nozzle of the cooler.
See Fig. 45 and 46.