Building Automation Systems (Bas); Use With On-Site Generators - McQuay WMC Installation, Operation And Maintenance Manual

Building Automation
Systems (BAS)
All MicroTech ® II controllers with Open Choices
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 .
® ®
McQuay International unit controllers strictly conform to the
interoperability guidelines of the LonMark
Association and BACnet International. They have received
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LonMark certification with optional L
®
module.
Protocol Options
The following protocol options are available:
• BACnet MS/TP
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• L W
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• BACnet IP
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• Modbus RTU
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• BACnet Ethernet
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The BAS communication module can be ordered with the
chiller and factory-mounted or can be field-mounted at any time
after the chiller unit is installed. Connection to the chiller for all
BAS protocols will be at the unit controller. An interface card,
depending on the protocol being used, will have been factory
installed in the unit controller if so ordered, or it can be field
installed.
If an interface module was ordered, the appropriate BAS
interface installation manual was shipped with the unit. If
necessary, contact your local McQuay International sales
office for a replacement manual or obtain one from
DaikinApplied.com. These documents can be easily found on
the website using the "Search Literature" feature.

Use with On-Site Generators

Magnitude Model WMC chillers have their total tonnage
®
divided between the number of compressors on the chiller.
The compressor(s) are operated with variable frequency
drives and if the unit has two compressors, the compressors
start sequentially. These features make Magnitude
especially appropriate for use in applications where they may
be required to run with on-site electrical generators. This is
particularly true when the generators are used for temporary
power when the utility power is lost.
Generator Sizing
Gas and diesel generators are sensitive to the compressor's
locked-rotor characteristics when the chillers start up. Use the
electrical data supplied with the performance output sheet,
obtained from the McQuay International sales office, for
generator sizing purposes. The chiller data sheet will show the
RLA, which is for each compressor. Refer to Electrical Data to
determine the LRA, which is based on the RLA. It is important
IOM 1210-1 • MAGNITUDE
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Interoperability
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chillers
®
MODEL WMC CHILLERS
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to size the generator to handle the LRA at startup.
Generator must be sized by an electrical engineer familiar
with generator applications.
Transfer Back to Grid Power
,
®
Proper transfer from stand-by generator power back to grid
power is essential to avoid compressor damage.
Stop the chiller before transferring supply power from the
generator back to the utility power grid. Transferring power
while the chiller is running can cause severe compressor
damage.
The necessary procedure for reconnecting power from the
generator back to the utility grid is as follows:
1. Set the generator to always run five minutes longer than
the unit start-to-start timer, which can be set from two to
sixty minutes. The actual setting can be viewed on the
OITS on the TIMERS Setpoint Screen (see
page 28).
2. Configure the transfer switch provided with the
generator to automatically shut down the chiller before
transfer is made. The automatic shut-off function can
be accomplished through a BAS interface or with the
"remote on/off" wiring connection shown in
Controller Box Wiring" on page
It is not necessary to shutdown the chiller if pumps are not
directly controlled by the chiller. Doing so, however, provides a
more coordinated restart.
A start signal can be given anytime after the stop signal since
the three-minute start-to-start timer will be in effect.
58
o
WARNING
WARNING
Figure 28 on
"Figure 13:
14.
www.DaikinApplied.com
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