LE_ENO C Q US
FLA -- Full Load Amps
LRA -- Locked Rotor Amps
MCA -- Minimum Circuit Arnps
MOCP -- Maximurn Overcurrent Protection
RLA -- Rated Load Arnps
NOTES:
1. In compliance with NEC (National Electrical Code) requirements
for multimotor and combination load equipment (refer to NEC
Articles 430 and 440), the overcurrent protective device for the
unit shall be Power Supply fuse. The CGA (Canadian Gas
Association) units may be fuse or circuit breake_
2. Minimum wire size is based on 60°0 copper wire. If other than
60°0 wire is used, or if length exceeds wire length in table,
deterrnine sizefrom NEC.
3. Unbalanced g-Phase Supply Voltage
Never operate _ motor where a phase imbalance in supply volt-
age is greater than 2%. Use the following formula to determine
the percentage of voltage imbalance.
% Voltage imbalance
- 100 x rnax voltage deviation from a_erage voltage
average voltage
. Heater capacity (kW) based on heater voltage of 208v & 240v.
If power distribution voltage to unit varies from rated heater
voltage, heater kW will vary accordingly.
EXAMPLE: Supply voltage is 230-3-60.
AB = 228 v
BC = 231 v
AC = 227 v
Average Voltage = 228 + 231 + 227
3
686
3
- 229
Determine maximum deviation from average voltage.
(AB) 229 - 228 - 1 v
(BC) 231 - 229 - 2 v
(AC) 229 - 227 = 2 v
Maximum deviation is 2 v.
Determine percent of voltage imbalance.
2
% Voltage Imbalance - 100 x --
229
- 0.8%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
contact your local electric utility cornpany '
IMPORTANT: If the supply voltage phase imbalance is
more than 2%,
immediately.
C03014
Balance Point Worksheet
70
60
_- 50
_3
O
3::O
_O
O :>,
g5 4o
do
a:* 30
c_:I:
mg
2O
10
Based on Indoor Entering Air of 70 F and Rated CFM S
-10 0 10 17 20 30 40 47 50 60
Outdoor Air Temp (Deg F)
Fig. 15 - 50SZ Balance Point Worksheet
---4_- 024
--1_030
--A-- 036
---X--- 042
+048
_060
C99009
REFRIGERANT CHARGE
The amount of refrigerant charge is listed on the unit nameplate
and/or the physical data table. Refer to the Refrigeration Service
Techniques Manual, Refrigerants Section.
NO CHARGE
Check for leak. Use standard evacuating techniques. After
evacuating system to 500 microns, weigh in the specified amount of
refrigerant (refer to system data plate).
LOW CHARGE COOLING
Use Cooling Charging Charts (see Table 5). Vary refrigerant until
the conditions of the chart are met. Note that charging charts are
different from the type normally used. (;harts are based on charging
the units to correct superheat for the various operating conditions.
Accurate pressure gauge and temperature sensing devices are
required. Connect the pressure gauge to the service port on the
suction line. Mount the temperature sensing device on the suction
line and insulate it so that the outdoor ambient does not affect the
reading. Indoor air CFM must be within the normal operating range
of the unit.
TO USE COOLING CHARGING CHARTS
Take the outdoor ambient temperature and read the suction pressure
gauge. Refer to the chart to determine what the suction temperature
should be.
NOTE: If the problem causing the inaccurate readings is a
refrigerant leak, refer to Check for Refrigerant Leaks section.
g
13
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