Fast Power Source Transfers; Water/Brine Reset; Reset Type; Demand Limit Control Option - Carrier AquaEdge 19XR series Start-Up, Operation And Maintenance Instructions Manual

Fast Power Source Transfers —
cal system is being prepared to transfer power from generator
power back to utility power or vice-versa, and the power trans-
fer is an open transition type, and time to transfer is less than 5
seconds, the chiller should be stopped before the transfer oc-
curs and restarted after the transfer has been completed. If the
chiller is not stopped before the transfer occurs, alarms on the
chiller can occur that must be manually reset, such as a circuit
breaker trip.
To accomplish shutdown and restart automatically, a set of
dry contacts should be opened 30 to 60 seconds before the
transfer occurs, then closed after the transfer is complete to re-
start the chiller. The contacts must be wired to the to the Re-
mote START/STOP contact in the starter or VFD (See the field
wiring diagrams) and the Remote Start contact configuration
must be enabled.
If power transfers take 5 seconds or longer, the chiller Auto
Restart after Power Failure feature (if enabled) will automati-
cally restart the chiller.
Water/Brine Reset —
mended the Single Cycle Drop Out in the ISM Configuration
be enabled. Chilled water capacity control is based on achiev-
ing and maintaining a CONTROL POINT temperature, which
is the sum of the LCW SET POINT or ECW SETPOINT (from
the SETPOINT screen) and a Water/Brine Reset value, if any.
CONTROL POINT is limited to a minimum of 35 F (+1.7 C)
for water, or 10 F (–12.2 C) for brine. Three types of chilled
water or brine reset are available and can be viewed or modi-
fied on the TEMP_CTL screen, which is accessed from the
EQUIPMENT SERVICE table.
The ICVC default screen indicates when the chilled water
reset is active. TEMPERATURE RESET on the MAINSTAT
screen indicates the amount of reset. The CONTROL POINT
will be determined by adding the TEMPERATURE RESET to
the SETPOINT.
To activate a reset type, access the TEMP_CTL screen and
input all configuration information for that reset type. Then, in-
put the reset type number (1, 2, or 3) in the SELECT/ENABLE
RESET TYPE input line.
RESET TYPE 1: 4 to 20 mA (1 to 5 vdc) TEMPERATURE
RESET – Reset Type 1 is an "automatic" reset utilizing a 4 to
20 mA or 1 to 5 vdc analog input signal provided from any
external sensor, controller, or other device which is appropri-
ately configured. Reset Type 1 permits up to ±30° F (±16.7° C)
of reset to the chilled water set point. Inputs are wired to termi-
nals J5-3 (–) and J5-4 (+) on the CCM (for 4 to 20 mA input).
In order to utilize a 1 to 5 vdc input, a 25-ohm resistor must be
wired in series with the + input lead (J5-4). For either input
type, SW2 DIP switch 2 should be set in the ON (up) position.
Inputs equivalent to less than 4 mA result in no reset, and
inputs exceeding 20 mA are treated as 20 mA.
RESET TYPE 2: REMOTE TEMPERATURE RESET —
Reset Type 2 is an automatic chilled water temperature reset
based on a remote temperature sensor input signal. Reset Type
2 permits ± 30 F (± 16 C) of automatic reset to the set point
based on a temperature sensor wired to the CCM module (see
wiring diagrams or certified drawings). The temperature sensor
must be wired to terminal J4-13 and J4-14. To configure Reset
Type 2, enter the temperature of the remote sensor at the point
where no temperature reset will occur (REMOTE TEMP –>
NO RESET). Next, enter the temperature at which the full
amount of reset will occur (REMOTE TEMP –> FULL
RESET). Then, enter the maximum amount of reset required to
operate the chiller (DEGREES RESET). Reset Type 2 can now
be activated.
RESET TYPE 3 — Reset Type 3 is an automatic chilled water
temperature reset based on cooler temperature difference.
Reset Type 3 adds ± 30 F (± 16 C) based on the temperature
When the electri-
For this application, it is recom-
difference between the entering and leaving chilled water
temperature.
To configure Reset Type 3, enter the chilled water tempera-
ture difference (the difference between entering and leaving
chilled water) at which no temperature reset occurs (CHW
DELTA T –> NO RESET). This chilled water temperature dif-
ference is usually the full design load temperature difference.
Next, enter the difference in chilled water temperature at which
the full amount of reset occurs (CHW DELTA T –> FULL RE-
SET). Finally, enter the amount of reset (DEGREES RESET).
Reset Type 3 can now be activated.
Demand Limit Control Option —
control option (20 mA DEMAND LIMIT OPT) is externally
controlled by a 4 to 20 mA or 1 to 5 vdc signal from an energy
management system (EMS). The option is set up on the
RAMP_DEM screen. When enabled, 4 mA is the 100% de-
mand set point with an operator-configured minimum demand
at a 20 mA set point (DEMAND LIMIT AT 20 mA).
The auto. demand limit is hardwired to terminals J5-1 (–)
and J5-2 (+) on the CCM. Switch setting number 3 on SW2
will determine the type of input signal. With the switch set at
the ON position the input is configured for an externally pow-
ered 4 to 20 mA signal. With the switch in the OFF position the
input is configured for an external 1 to 5 vdc signal. In order to
use a 1 to 5 vdc input instead of 4 to 20 mA, install a 25-ohm
resistor in series with the + lead at terminal J5-2.
Surge Prevention — Constant Flow and Vari-
able Primary Flow (VPF) —
when the lift becomes so high that the gas flow across the im-
peller reverses. This condition can eventually cause chiller
damage. The surge prevention algorithm notifies the operator
that chiller operating conditions are marginal and to take action
to help prevent chiller damage such as lowering entering con-
denser water temperature.
The surge prevention algorithm is an operator-configurable
feature that can determine if lift conditions are too high for the
compressor and then take corrective action. Lift is defined as
the difference between the saturated temperature at the impeller
eye and at the impeller discharge. The maximum lift a particu-
lar impeller wheel can perform varies with the gas flow across
the impeller and the size of the wheel.
Variable Flow Surge prevention is the current standard for
both constant and variable primary flow chilled water systems.
Variable Primary Flow Surge Prevention does not require a
measurement of COOLER DELTA T and is thus unaffected by
changes in flow. With Variable Primary Flow Surge Preven-
tion there is no difference in field configuration between con-
stant and variable flow water systems.
The controls calculate the conditions at which the compres-
sor will surge based on operating conditions and configured
values entered into the OPTIONS screen.
The configurations as used by the controls would plot out
on a graph as a curved or stepped line. If the present operating
conditions plot at or above this line, surge prevention is turned
on.
The way in which surge prevention functions will differ
with the presence or absence of hot gas bypass and variable
speed drive.
Hot Gas Bypass (Optional) Algorithm —
hot gas bypass solenoid valve is present and the HGBP OP-
TION in the OPTIONS table is set to 1 or 2, this operator con-
figurable feature can determine if load conditions are too low
for the compressor and corrective action can be taken.
HGBP OPTION = 0 — The HGBP algorithm is disabled.
HGBP OPTION = 1 (VFD OPTION DISABLED) — The
algorithm determines if corrective action is necessary by
checking the chiller operating point against an operator
56
The demand limit
A surge condition occurs
If a