Minutes Off Time; Lead/Lag Determination; Capacity Sequence Determination; Capacity Control Overrides - Carrier Air Conditioner Operation And Service Manual

ADDING ADDITIONAL UNLOADERS — See Table 6
below for required hardware.
Follow accessory instructions for installation. Connect un-
loader coil leads to PINK wires in compressor A1/B1 junction
box. Configuration items CA.UN and CB.UN in the OPT1
sub-mode of the configuration mode must be changed to match
the new number of unloaders. Two unloaders cannot be used
with hot gas bypass on a single circuit.
MINUTES LEFT FOR START — This value is displayed
only in the network display tables (using Service Tool or
ComfortWORKS® software) and represents the amount of
time to elapse before the unit will start its initialization routine.
This value can be zero without the machine running in many
situations. This can include being unoccupied, ENABLE/OFF/
REMOTE CONTACT switch in the OFF position, CCN not
allowing unit to start, Demand Limit in effect, no call for cool-
ing due to no load, and alarm or alert conditions present. If the
machine should be running and none of the above are true, a
minimum off time (DELY, see below) may be in effect. The
machine should start normally once the time limit has expired.
MINUTES OFF TIME (DELY, Configuration Mode under
OPT2) — This user configurable time period is used by the
control to determine how long unit operation is delayed after
power is applied/restored to the unit. Typically, this time period
is configured when multiple machines are located on a single
site. For example, this gives the user the ability to prevent all
the units from restarting at once after a power failure. A value
of zero for this variable does not mean that the unit should be
running.
LOADING SEQUENCE — The 30GTN,R and 30GUN,R
compressor efficiency is greatest at partial load. Therefore, the
following sequence list applies to capacity control.
The next compressor will be started with unloaders ener-
gized on both lead compressors.
All valid capacity combinations using unloaders will be
used as long as the total capacity is increasing.
LEAD/LAG DETERMINATION (LLCS, Configuration
Mode under OPT2) — This is a configurable choice and is
factory set to be automatic (for sizes 080-420) or Circuit A
leading (for 040-070 sizes). For 040-070 sizes, the value can be
changed to Automatic or Circuit B only if an accessory unload-
er is added to compressor B1. For 080-420 sizes, the value can
be changed to Circuit A or Circuit B leading, as desired. Set at
automatic, the control will sum the current number of logged
circuit starts and one-quarter of the current operating hours for
each circuit. The circuit with the lowest sum is started first.
Changes to which circuit is the lead circuit and which is the lag
are also made when total machine capacity is at 100% or when
UNIT
30GTN,GTR,GUN,GUR
040 (60 Hz)
040 (50 Hz)
045 (60 Hz)
045 (50 Hz)
050-070
080-110**
130 (60 Hz)
130 (50 Hz)
150-210**
LEGEND
CBX — Compressor Expansion Board
Table 6 — Required Hardware for Additional Unloaders
FACTORY ADDITIONAL
COMP.
STANDARD UNLOADERS
A1 1
B1 0
A1 1
B1 0
A1 1
B1 0
A1 1
B1 1
A1 1
B1 1
there is a change in the direction of capacity (increase or de-
crease) and each circuit's capacity is equal.
CAPACITY SEQUENCE DETERMINATION (LOAD,
Configuration Mode under OPT2) — This is configurable as
equal circuit loading or staged circuit loading with the default
set at equal. The control determines the order in which the steps
of capacity for each circuit are changed. This control
choice does NOT have any impact on machines with only
2 compressors.
CAPACITY CONTROL OVERRIDES — The
overrides will modify the normal operation of the routine.
Deadband Multiplier — The user configurable Deadband
Multiplier (Z.GN, Configuration Mode under SLCT) has a
default value of 1.0. The range is from 1.0 to 4.0. When set to
other than 1.0, this factor is applied to the capacity Load/Un-
load Factor. The larger this value is set, the longer the control
will delay between adding or removing stages of capacity.
Figure 17 shows how compressor starts can be reduced over
time if the leaving water temperature is allowed to drift a larger
amount above and below the set point. This value should be set
in the range of 3.0 to 4.0 for systems with small loop volumes.
First Stage Override — If the current capacity stage is zero,
the control will modify the routine with a 1.2 factor on adding
the first stage to reduce cycling. This factor is also applied
when the control is attempting to remove the last stage of
capacity.
Slow Change Override — The control prevents the capacity
stages from being changed when the leaving fluid temperature
is close to the set point (within an adjustable deadband) and
moving towards the set point.
Ramp Loading (CRMP, Configuration Mode under SLCT) —
Limits the rate of change of leaving fluid temperature. If the
unit is in a Cooling mode and configured for Ramp Loading,
the control makes 2 comparisons before deciding to change
stages of capacity. The control calculates a temperature differ-
ence between the control point and leaving fluid temperature. If
the difference is greater than 4° F (2.2° C) and the rate of
change (°F or °C per minute) is more than the configured Cool-
ing Ramp Loading value (CRMP), the control does not allow
any changes to the current stage of capacity.
Low Entering Fluid Temperature Unloading — When the
entering fluid temperature is below the control point, the con-
trol will attempt to remove 25% of the current stages being
used. If exactly 25% cannot be removed, the control removes
an amount greater than 25% but no more than necessary. The
lowest stage will not be removed.
UNLOADER
PACKAGE*
0 N/A
1 06EA-660---138
0 N/A
1
06EA-660---138
2
1
1 06EA-660---138
2
1
06EA-660---138
1
1
06EA-660---138
1
*Requires one per additional unloader.
†2 solenoid coils are included in the CXB Accessory.
**And associated modular units.
26
SOLENOID
CXB ACCESSORY†
COIL
N/A
Not Required
EF19ZE024
N/A
Not Required
EF19ZE024
Not Required 30GT-911---031
EF19ZE024 Not Required
Not Required 30GT-911---031
Not Required 30GT-911---031
EF19ZE024 Not Required
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