Advertisement
LEGEND
FLA- Full Load
Amps
HACR
- Heating,
Air Conditioning
and Refrigeration
IFM- Indoor
(Evaporator)
Fan Motor
LRA- Locked
RotorAmps
MCA - MinimumCircuitAmps
MOCP
- Maximum
Overcurrent
Protection
NEC - National
Electrical
Code
OFM - Outdoor
(Condenser)
Fan Motor
RLA- Rated
Load Amps
*Fuse
or HACR
circuit
breaker
208/230
v 75-kW
Electric
Heat
units
must
use dual-point
wiring.
The main
table
lists the
branch
circuit
values
for the
refrigeration
part of the
system.
The following
two tables
list the branch
circuit
values
for the electric
heat
and values
for a feeder
circuit
for both
branch
circuits.
NOTES:
1.
In compliance
with
NEC
requirements
for muttimotor
and
combination
load
equipment
(refer
to NEC
Articles
430
and
440),
the overcurrent
protective
device
for the
unit shall
be fuse
or HACR
breaker.
2.
Unbalanced
3-Phase
Supply
Voltage
Never
operate
a motor
where
a phase
imbalance
in supply
voltage
is greater
than
2%.
Use the following
formula
to determine
the percentage
of voltage
imbalance.
% Voltage
Imbalance
= 1 O0 x
max
voltage
deviation
from
average
voltage
average
voltage
Example:
Supply
voltage
is 460-3-60
AB = 452
v
BC = 464 v
AC = 455 v
Average
Voltage
=
452
+ 464
+ 455
3
1371
3
=
457
Determine
maximum
deviation
from
average
voltage.
(AB) 457
452
= 5 v
(BC)
464 - 457
= 7 v
(AC)
457 - 455
= 2 v
Maximum
deviation
is 7 v.
Determine
percent
of voltage
imbalance.
7
% Voltage
Imbalance
= 1 O0 x
457
= 1.53%
This
amount
of phase
imbalance
is satisfactory
as it is below
the
maximum
allowable
2%.
II_IPOI,tq:&NT:
ff the supply
voltage
phase
irnbaiance
is rnorc
than
2%,
contact
your
local
electric
utility
company
irnrnediatety.
3. The convenience
outlet
full Ioad
amps
(FLA) are
5.3,
and
3 for
208/230,460,
575-V
units,
respectively.
4. The convenience
outlet
full load
amps
(FLA) are
5, 3 and
3 for
208/230,460,
575-v
units,
respectively.
5. The FLA load
amps
provided
in the
table
for electric
heaters
are based
on 208/240,480
and
600 v.
6.
MCA calculation
for 50PG
units with
electric
heaters
over
50 kW is = 1.25
x (IFM
+ Power
Exhaust
+ Convenience
Outlet
FLA amps)
+ 1.00
x
(Electric
Heater
FLA).
I,o
Advertisement
