40
Operating Limitations
TEMPERATURES — See Table 39 for 30MP standard
temperature limits. The 30MPW050-071 and 30MPA050-
071 units use different compressors that require different
operating envelopes. The 30MPW050-071 units (standard
condensing) use water-cooled optimized compressors,
which operate at lower condensing temperatures. The
30MPA050-071 units and 30MPW050-071 heat reclaim
units use air-cooled optimized compressors, which allow
for higher condensing temperatures.
High Cooler Leaving Chilled Water (Fluid) Temperatures
(LCWT) — During start-up with cooler the LCWT should not
be above approximately 60 F (16 C).
Low Cooler LCWT
— For standard units with fresh water,
the LCWT must be no lower than 40 F (4.4 C). For standard
units with a proper brine solution, the LCWT must be no lower
than 32 F (0° C). If the unit is the factory-installed optional
medium temperature brine unit, the cooler LCWT can go
down to 15 F (–9.4 C).
Table 39 — Temperature Limits for
Standard 30MP Units
LEGEND
*For sustained operation, EWT should not exceed 85 F (29.4 C).
†Unit requires modification below this temperature.
VOLTAGE — ALL UNITS
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:
The maximum voltage deviation is the largest difference
between a voltage measurement across 2 legs and the average
across all 3 legs.
Example: Supply voltage is 240-3-60.
AB = 243 v
BC = 236 v
AC = 238 v
1. Determine average voltage:
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.
3. Determine percent voltage imbalance:
This voltage imbalance is satisfactory as it is below the
maximum allowable of 2%.
Control Circuit Power
— Power for the control circuit is
supplied from the main incoming power through a factory-
installed control power transformer (TRAN1) for all models.
Field wiring connections are made to the LVT.
OPERATION SEQUENCE
The unit is started by putting the ENABLE/OFF/REMOTE
CONTROL switch in the ENABLE or REMOTE CONTROL
position. When the unit receives a call for cooling (either from
the internal control or CCN network command or remote con-
trol closure), the unit stages up in capacity to maintain the leav-
ing fluid set point. The first compressor starts 1
1
/
2
to 3 minutes
after the call for cooling.
For all units, if temperature reset is being used, the unit con-
trols to a higher leaving-fluid temperature as the building load
reduces. If demand limit is used, the unit may temporarily be
unable to maintain the desired leaving-fluid temperature be-
cause of imposed power limitations.
SERVICE
Service Test —
Both main power and control circuit
power must be on.
The Service Test function should be used to verify proper
operation of condenser output, compressors, minimum load
CAUTION
Do not operate with cooler leaving chiller water (fluid)
temperature (LCWT) below 32 F (0° C) for standard units
with proper brine solution, 40 F (4.4 C) for the standard
units with fresh water, or below 15 F (–9.4 C) for units fac-
tory built for medium temperature brine, or unit damage
may occur.
TEMPERATURE LIMIT
30MPA,
30MPW015-045,
30MPW050-071
HIGH
CONDENSING
STANDARD
30MPW050-071
FCFC
Maximum Condenser LWT
140 60 120 49
Minimum Condenser EWT
65 18 65 18
Maximum Cooler EWT*
75 23 75 23
Maximum Cooler LWT
60 15 60 15
Minimum Cooler LWT†
40 4 40 4
EWT —
Entering Fluid (Water) Temperature
LWT —
Leaving Fluid (Water) Temperature
IMPORTANT: Medium temperature brine duty application
(below 32 F [0° C] LCWT) for chiller normally requires
factory modification. Contact your Carrier representative
for applicable LCWT range for standard water-cooled
chiller in a specific application.
% Voltage Imbalance = 100 x
max voltage deviation
from avg voltage
average voltage
Average voltage =
243 + 236 + 238
3
=
717
3
= 239
% Voltage Imbalance = 100 x
4
239
= 1.7%
IMPORTANT: If the supply voltage phase imbalance is
more than 2%, contact your local electric utility company
immediately. Do not operate unit until imbalance condition
is corrected.
WARNING
Electrical shock can cause personal injury and death. Shut
off all power to this equipment during service. There may
be more than one disconnect switch. Tag all disconnect
locations to alert others not to restore power until work is
completed.
To Next Page
Loading...
