IOM 1274-3 • CENTRIFUGAL WATER CHILLERS 18 www.DaikinApplied.com
DANGER
If a separate control power source is used, the following
must be done to avoid severe personal injury or death from
electrical shock: 1) Place a notice on the unit that multiple
power sources are connected to the unit; and 2) Place a
notice on the main control power disconnects that another
source of power to the unit exists.
In the event a transformer supplies control voltage, it must be
rated at 3 KVA, with an inrush rating of 12 KVA minimum at
80% power factor and 95% secondary voltage. For control wire
sizing, refer to NEC Articles 215 and 310. In the absence of
complete information to permit calculations, the voltage drop
should be physically measured.
Table 7: Control Power Line Sizing - 115 to 220 Vac
Maximum Length, ft (m) Minimum Wire Size (AWG)
0 (0) to 50 (15.2) 12
NOTE:
1. Maximum length is the distance a conductor will traverse
between the control power source and the unit control
panel.
2. Panel terminal connectors will accommodate up to
number 10 AWG wire. Larger conductors will require an
intermediate junction box.
not desired.
Surge Capacitors
Surge capacitors are an option for some unit-mounted, low
VFDs) to protect compressor motors from electrical damage
resulting from high voltage spikes. If ordered, the capacitors
are factory-mounted and wired in the starter enclosure.
(BAS)
All MicroTech
®
controllers with an open protocol platform are
capable of BAS communications, providing easy integration
and comprehensive monitoring, control, and two-way data
exchange with open standard protocols such as LonTalk
®
,
Modbus® or BACnet
®
.
Daikin Applied unit controllers strictly conform to the
interoperability guidelines of the LonMark® Interoperability
Association and BACnet® International. They have
W®
communication module.
Protocol Options
The following protocol options are available:
• BACnet
®
MS/TP
• BACnet
®
IP
• BACnet
®
Ethernet
• LW
®
• Modbus
®
RTU
The BAS communication module can be ordered with the
after the chiller unit is installed. Connection to the chiller for all
BAS protocols will be at the unit controller.
If an interface module was ordered, the appropriate BAS
interface installation manual was shipped with the unit. If
additional manual or download from www.DaikinApplied.com.
Use with On-Site Generators
Centrifugal chillers using oil may be run with On-Site
Generators when utility power is lost. The HVAC system
and chiller have to be disconnected from the power grid and
connected to the generator power. Then enable the HVAC
system while on the generator.
Generator Sizing
Natural gas and diesel generators are sensitive to the peak
current loads of the chiller. Use the electric data on the Starters
supplied with the chiller or the chiller performance rating sheet
sizing purposes. The reference data will show the RLA and
LRA, which is for each compressor. It is important to size the
generator to handle the LRA for the compressor motor for
starting.
WARNING
Generator must be sized by an electrical engineer familiar
with generator applications.
Transfer Back to Grid Power
If the generator to power grid has synchronous power switch
capability then it can be done at any time. Usually this switch
does not exist so the switch is done by shutting down the
HVAC system including the chiller that is running on the
generator. Then switch the power for the HVAC system to the
power from the grid and then turning the HVAC system back on
including the Chiller.
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