Carrier HERMETIC SCREW LIQUID CHILLERS 23 XL - Manual (Page 33)

IMPORTANT: Refer to certified drawings for addi-
tional information. Certified drawings are available upon
request.
LEGEND
Required Power Wiring
Required Control Wiring
Options Wiring
NOTES:
I. GENERAL
1.0 Starters shall be designed and manufactured in accordance with
Carrier Engineering Requirement Z-375.
1.1 All field-supplied conductors, devices, field-installation wiring, and ter-
mination of conductors and devices, must be in compliance with all
applicable codes and job specifications.
1.2 The routing of field-installed conduit and conductors and the location
of field-installed, devices must not interfere with equipment access or
the reading, adjusting, or servicing of any component.
1.3 Equipment installation and all starting and control devices must com-
ply with details in equipment submittal drawings and literature.
1.4 Contacts and switches are shown in the position they would assume
with the circuit deenergized and the chiller shut down.
1.5 WARNING — Do not use aluminum conductors.
II. POWER WIRING TO STARTER
2.0 Power conductor rating must meet minimum unit nameplate voltage
and compressor motor RLA (rated load amps).
When (3) conductors are used:
Minimum ampacity per conductor = 1.25 x compressor RLA
When (6) conductors are used:
Minimum ampacity per conductor = 0.721 x compressor RLA
2.1 Lug adapters may be required if installation conditions dictate that con-
ductors be sized beyond the minimum ampacity required. Solid-state
starters are provided with:
A. Two (2) 0-250 MCM lugs provided per phase for power conductor
terminations when compressor motor RLA is 400 amps or less.
B. Three (3), 250-500 MCM lugs provided per phase for power con-
ductor terminations when compressor motor RLA is more than
400 amps.
Wye-Delta starters are provided with:
A. Two (2) 250-500 MCM lugs provided per phase for power conduc-
tor terminators when compressor motor RLA is 420 amps or less.
B. Two (2) #1-500 MCM lugs provided per phase for power conductor
terminations when compressor motor RLA is more than
420 amps.
2.2 Power conductors to starter must enter through top of enclosure. Flex-
ible conduit should be used for the last few feet to the enclosure to
provide unit vibration isolation.
2.3 Compressor motor and controls must be grounded by using equip-
ment grounding lugs provided inside starter enclosure.
2.4 Wye-Delta starters require the assembly and the installation of a ‘‘Top
Hat’’ (located inside enclosure) to provide the required wire bending
space for incoming power leads.
III. CONTROL WIRING
3.0 Field supplied control conductors to be at least 18 AWG (American Wire
Gage) or larger.
3.1 Chilled water and condenser water flow switch contacts, optional re-
mote start device contacts and optional spare safety device contacts,
must have 24 vdc rating. Max current is 60 ma, nominal current
is 10 ma. Switches with gold plated bifurcated contacts are
recommended.
3.2 Remove jumper wire between 12A and 12B before connecting auxil-
iary safeties between these terminals.
3.3 Pilot relays can control cooler and condenser pump and tower fan mo-
tor contactor coil loads rated 10 amps at 115 vac up to 3 amps at 600
vac. Control wiring required for Carrier to start pumps and tower fan
motors must be provided to assure machine protection. If primary pump
and tower fan motor control is by other means, also provide a parallel
means for control by Carrier. Do not use starter control transformer as
the power source for pilot relay loads.
3.4 Do not route control wiring carrying 30 v or less within a conduit which
has wires carrying 50 v or higher or along side wires carrying 50 v or
higher.
Fig. 34 — 23XL Typical Field Wiring with Optional Unit-Mounted Starter (Frame 1 and 2 Machines Shown)
33