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Legend and Notes for Tables 21 and 22
LEGEND:
BRKR
---
Circuit breaker
C.O.
---
Convenience outlet
DISC.
---
Disconnect
FLA
---
Full load amps
LRA
---
Locked rotor amps
MCA
---
Minimum circuit amps
P .E.
---
Power exhaust
Pwrd fr/ unit
---
Powered from unit
PWRD C.O.
---
Powered convenience outlet
UNPWR C.O.
---
Unpowered convenience outlet
NOTES:
1. In compliance with NEC requirements for multimotor and combination load
equipment (refer to NEC Articles 430 and 440), the overcurrent protective device
for the unit shall be fuse or HACR breaker. Canadian units may be fuse or circuit
breaker.
2. For 208/230 v units, where one value is shown it is the same for either 208 or
230 volts.
3. 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
= 100 x
Example: Supply voltage is 230-3-60
AB = 224 v
BC = 231 v
AC = 226 v
(224 + 231 + 226)
Average Voltage =
3
=
227
Determine maximum deviation from average voltage.
(AB) 227 – 224 = 3 v
(BC) 231 – 227 = 4 v
(AC) 227 – 226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
% Voltage Imbalance
= 100 x
227
= 1.76%
This amount of phase imbalance is satisfactory as it is below the maximum
allowable 2%.
IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact
your local electric utility company immediately.
Smoke Detectors
Smoke detectors are available as factory- - installed options on
48LC models. Smoke detectors may be specified for Supply
Air only or for Return Air without or with economizer or in
combination of Supply Air and Return Air. All components
necessary for operation are factory- - provided and mounted.
The unit is factory- - configured for immediate smoke detector
shutdown operation; additional wiring or modifications to
Step 1
max voltage deviation from average voltage
average voltage
681
=
3
4
Fig. 66 - - Completing Installation of Return Air Smoke Sensor
the Integrated Staging Control (ISC) board may be necessary
to complete the unit and smoke detector configuration to
meet project requirements.
Units equipped with factory- - optional Return Air smoke
detectors require a relocation of the sensor module at unit
installation. See Fig. 65 for the as shipped location.
Completing Installation of Return Air Smoke Sensor:
1. Unscrew the two screws holding the Return Air
Smoke Detector assembly. See Fig. 66, Step 1. Save
the screws.
2. Turn the assembly 90 degrees and then rotate end to
end. Make sure that the elbow fitting is pointing
down. See Fig. 66, Step 2.
3. Screw the sensor and detector plate into its operating
position using screws from Step 1. See Fig. 66, Step 3.
4. Connect the flexible tube on the sampling inlet to the
sampling tube on the base pan.
Return Air
Smoke Detector
(as shipped)
Fig. 65 - - Return Air Smoke Detector, Shipping Position
Additional Application Data —
Refer to Factory Installed Smoke Detectors for Small and
Medium Rooftop Units 2 to 25 Tons for discussions on
additional control features of these smoke detectors
including multiple unit coordination.
Step 2
64 64
Step 3
C12282
C12283
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