QUANTECH
86
FORM QWC4-NM1 (221)
ISSUE DATE: 02/28/2021
SECTION 6 - OPERATION
TABLE 27 -
LOAD LIMITING VALUES
PARAMETER
(X AXIS UNITS)
X POINT
Y POINT
Z POINT
MOTOR CURRENT (%FLA)
Active Current Limit Setting –
2% FLA
Active Current Limit Setting
Active Current Limit S
5% FLA
DISCHARGE PRESSURE
High Discharge Pressure
Cutout – 15 psig
High Discharge Pressure
Cutout – 15 psig
High Discharge Pressure
Cutout
EVAPORATOR PRESSURE
Low Evaporator Pressure
10 psig
Low Evaporator Pressure
5 psig
Low Evaporator Pressure
Cutout
VSD INTERNAL AMBIENT
TEMP
VSD Internal Ambient Cutout
– 3°F
VSD Internal Ambient Cutout
– 2°F
VSD Internal Ambient Cutout
VSD BASEPLATE TEMP
VSD Baseplate Temp – 8°F
VSD Baseplate Temp – 4°F
VSD Baseplate Temp
LEAVING CHILLED LIQUID
TEMPERATURE
(HEAT PUMP MODE ONLY)
Low Leaving Chilled Liquid
Temp Cutout – + 4°F
Low Leaving Chilled Liquid
Temp Cutout – +2°F
Low Leaving Chilled Liquid
Temp Cutout – +2°F
NOTE:
All of the controls above are active immediately at start-up.
•
Remote BAS Comms Reset
: Set the LCHLT
setpoint via the BAS COMMS. The control panel
will only accept a remote setpoint from the BAS,
if the control panel is in REMOTE CONTROL
mode (under OPTIONS). If the control panel is
in LOCAL CONTROL mode, the BAS setpoint
will be ignored, and the remote LCHLT setpoint is
set to the local setpoint. The minimum and maxi-
mum allowable reset values will be the same as
those allowable programmable values for the lo-
cal setpoint. If these values are exceeded by the
BAS, the minimum or maximum value will be
used.
•
Remote Analog Reset
: Set the remote LCHLT
setpoint via the REMOTE TEMPERATURE
RESET analog input. A zero signal input (0%)
equates to a 0°F (0°C) offset to the local setpoint.
A full scale signal input (100%) equates to a posi-
tive offset to the local setpoint equal to the pro
-
grammable maximum REMOTE TEMP RESET.
The offset is linear and may be adjusted between
0% and 100% points. The maximum setpoint
allowed is the maximum programmable local
setpoint, which will be capped at this value, if the
calculated setpoint with temperature offset ex
-
ceeds this value.
This input may be used either in LOCAL or RE-
MOTE CONTROL mode, which will only oper-
ate if enabled under the UNIT SETUP mode and
the OPTIONS key. The input will be ignored if
the REMOTE TEMP RESET is disabled un-
der the OPTIONS key, or if there are valid BAS
Pulldown Current Limit Setpoint
Set this setpoint under the PROGRAM key, which
is only active on start-up for the time defined by the
PULLDOWN CURRENT LIMIT TIME. After the run
time has exceeded this time, the PULLDOWN CUR-
RENT LIMIT setpoint is ignored.
This control is useful in limiting current pulldown de-
mand during peak usage periods where electric costs
are highest.
Limiting current may interfere with
capacity control, pulling down chilled
liquid temperatures on hot water starts,
and maintaining chilled liquid setpoints.
If there are questions about the following reset con-
trols, contact a Quantech BAS representative for de-
tails on BAS controls and capabilities.
Leaving Chilled Liquid Temperature (LCHLT)
Reset Control
The LCHLT RESET CONTROL is used to reset the
actual LCHLT setpoint used in capacity control. See
the three methods below to reset the LCHLT setpoint:
•
Local Cooling Reset:
Reprogram the local cool-
ing setpoint under the SETPOINTS key, which
is the value to which the unit will control the
LCHLT, if no other method is active.
REMOTE TEMPERATURE LIMIT RESET is
only possible if the option is enabled by select-
ing OPTIONS key, and programmable password
protected UNIT SETUP MODE from the factory.
Summary of Contents for QWC4
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