Capacity Control; Minutes Off Time - Carrier Ecologic 30GX080-265 Controls, Start-Up, Operation, Service, And Troubleshooting

COMM3
MOTOR INPUT
TEMPERATURE
Where current limitations exist, the Wye-Delta option may
be used. See Fig. 3. This option uses a factory-installed starter
assembly for each compressor, which consists of 3 contac-
tors labelled 1M, 2M, and S. As the compressor is started,
the CPM module energizes contactors 1M and S, which con-
nects and energizes the motor windings in a Wye configu-
ration. The starting current required will be approximately
60% less than that required for an XL start due to the higher
impedance of the motor windings when Wye connected. The
compressor will attain about 100% of its normal operating
speed (approximately 3 to 6 seconds) before the CPM mod-
ule deenergizes the S contactor and energizes the 2M con-
tactor, switching the compressor windings to a Delta wiring
configuration. The S and 2M contactors in the starter assem-
bly are both mechanically and electrically interlocked so that
they will not both be energized at the same time.
Do not alter the factory-installed power wiring from the
control box terminal block to the compressor junction block.
Doing so will cause permanent damage to the compressor
and will require that the compressor be replaced.
Capacity Control —
The control system cycles com-
pressors, loaders, and minimum load control valves to main-
tain the user-configured leaving chilled fluid temperature set
point. Entering fluid temperature is used by the microproces-
sor to determine the temperature drop across the cooler and
is used in determining the optimum time to add or subtract
capacity stages. The chilled fluid temperature set point can
be automatically reset by the return temperature reset or space
and outdoor-air temperature reset features. It can also be re-
set from an external 4 to 20 mA signal (requires field-
supplied 500-ohm, 1 ⁄ watt resistor), or from a network signal.
2
The capacity routine runs every 30 seconds. The routine
attempts to maintain the Control Point at the desired set point.
Each time it runs, the control reads the entering and leaving
fluid temperatures. The control determines the rate at which
conditions are changing and calculates 2 variables based on
these conditions. Next, a capacity ratio (Load/Unload Fac-
tor under ) is calculated using the 2 variables to
determine whether or not to make any changes to the current
stages of capacity. This ratio value ranges from − 100 to
+ 100%. If the next stage of capacity is a compressor, the
COMPRESSOR PROTECTION MODULE (CPM)
L1
24/115/230 VAC
L2 INPUTS/OUTPUTS
L3
CURRENT TOROID
INPUT PLUG
1
2
3
1
ADDRESS DIP
SWITCH
2
COMPRESSOR
T
MUST TRIP
AMPS HEADER
T
Fig. 1 — Compressor Protection Module
PUSH THIS SIDE OF SWITCH
DOWN TO SET ADDRESS
1
0
LED — Light-Emitting Diode
NOTES:
RED LED
1. The red LED blinks continuously when the module
is operating properly.
YELLOW LED
2. The yellow LED blinks during automatic reset alarm,
and is continuously lit when the manual reset alarm
GREEN LED is active.
3. The green LID blinks continuously when communi-
cating properly with PSIO-1.
control starts (stops) a compressor when the ratio reaches
+ 100% (− 100%). If the next stage of capacity is a loader,
the control energizes (deenergizes) a loader when the ratio
reaches + 60% (− 60%). Loaders are allowed to cycle faster
than compressors, to minimize the number of starts and stops
on each compressor. A delay of 90 seconds occurs after each
capacity step change.
MINUTES LEFT FOR START — This value is displayed in
the Status subfunction and represents the amount of time to
elapse before the unit is started. This value can be zero with-
out the machine running in many situations. This can in-
clude being unoccupied, LOR switch in the OFF position,
CCN not allowing unit to start, Demand Limit in effect, no
call for cooling 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 may be in effect. The
machine should start normally once the time limit has
expired.

MINUTES OFF TIME (

urable time period is used by the control to determine how
long unit operation is delayed after power is applied/
restored to the unit. It is also used to delay compressor re-
starts after the unit has shut off its lowest stage of capacity.
Typically, this time period is configured when multiple ma-
chines 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 30GX,HX chiller effi-
ciency is greatest at full load. Therefore, the following se-
quence list applies to capacity control.
1. The next compressor is not started until all others are run-
ning at 100%.
2. The second unloading stage is only used during initial
capacity staging of the unit at start-up.
3. Whenever a compressor is started in a circuit, the loaders
in the circuit are deenergized for 15 seconds before the
compressor is started. The loaders are energized 90 sec-
onds after the compressor is started.
6
ROCKER DOWN
4 3 2 1
2 3
4 5
) — This user config-