Operating Limitations - Carrier AquaForce B Series Controls, Start-Up, Operation, Service And Troubleshooting Instructions

Operating Limitations

TEMPERATURES
Unit operating temperature limits are listed in the table below.
TEMPERATURE
Maximum Ambient Temperature
Minimum Ambient Temperature*
Maximum Evaporator EWT†
Maximum Evaporator LWT
Minimum Evaporator LWT
Maximum Evaporator Glycol EWT†
Minimum Evaporator Glycol LWT
LEGEND
EWT — Entering Fluid (Water) Temperature
LWT — Leaving Fluid (Water) Temperature
* Lowest allowable ambient temperature for the standard unit to start
and operate is 32°F (0°C). With the inclusion of wind baffles and vari-
able speed fans (field fabricated and installed), the unit is capable to
start as low as 0°F (–17.8°C) and to operate as low as –20°F (–29°C)
ambient temperature.
† For sustained operation, EWT should not exceed 70°F (21.1°C).
** Unit requires brine fluid for operation below this temperature.
Low Ambient Temperature Operation
If unit operating temperatures below 32°F (0°C) are expected,
the following measures are recommended:
• Consider higher loop volumes, 6 to 10 gallons per nominal ton.
• Loop freeze protection with glycol is strongly recommend-
ed to a minimum of 15°F (8.3°C) below lowest anticipated
ambient temperature.
• Chilled water pump control is required.
• If wind velocity is expected to be greater than 5 mph
(8 km/h) wind baffles and brackets must be field fabricated
and installed. See the 30XV Installation Instructions for
more information.
VOLTAGE
Main Power Supply
Minimum and maximum acceptable supply voltages are listed
in the Installation Instructions.
Unbalanced 3-Phase Supply Voltage
Never operate a motor where a phase imbalance between
phases is greater than 2%.
To determine percent voltage imbalance:
% Voltage Imbalance = 100 x max voltage deviation from avg voltage
The maximum voltage deviation is the largest difference be-
tween a voltage measurement across 2 legs and the average
across all 3 legs.
Example: Supply voltage is 240-3-60.
AB = 243v
BC = 236v
AC = 238v
Corner Grounded Delta Supply
The Compressor and Fan VFDs used on 30XV units are automati-
cally compatible with a Corner Grounded Delta Power Supply to
the system. No changes are required to be made to the VFDs.
1. Determine average voltage:
Average voltage = 243+236+238
=
=
F
125
32
95
60
38**
95
30
average voltage
3
717
3
239
2. Determine maximum deviation from average voltage:
(AB) 243 – 239 = 4 v
(BC) 239 – 236 = 3 v
(AC) 239 – 238 = 1 v
Maximum deviation is 4 v.
8. Determine percent voltage imbalance:
C
52
% Voltage Imbalance = 100 x
0
35
15
3.3
This voltage imbalance is satisfactory as it is below the
35
maximum allowable of 2%.
16.7
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact the local electric utility company
immediately. Do not operate unit until imbalance condition
is corrected.
MINIMUM FLUID LOOP VOLUME
To obtain proper temperature control, loop fluid volume must be
at least 3 gallons per ton (3.25 L per kW) of chiller nominal ca-
pacity for air conditioning and at least 6 gallons per ton (6.5 L
per kW) for process applications or systems that must operate at
low ambient temperatures (below 32°F [0°C]). Refer to applica-
tion information in Product Data literature for details.
FLOW RATE REQUIREMENTS
Standard chillers should be applied with nominal flow rates
within those listed in the Minimum and Maximum Evaporator
Flow Rates table. Higher or lower flow rates are permissible to
obtain lower or higher temperature rises. Minimum flow rates
must be exceeded to assure turbulent flow and proper heat
transfer in the evaporator. See Tables 33 and 34. See Fig. 45-50
for evaporator pressure drop curves.
Operation below minimum flow rate could generate alarms,
which could result in damage to the evaporator.
Consult application data section in the Product Data literature
and job design requirements to determine flow rate require-
ments for a particular installation.
50
4
239
=
1.7%
CAUTION