Electrical/Utility Interests; Energy Management; Demand Limiting; Remote On-Off Control - Carrier 30GTN Product Data

Application data (cont)

Electrical/utility interests

Energy management — Use of energy management practices
can significantly reduce operating costs, especially during off-
peak modes of operation. Demand limiting and temperature
reset are 2 techniques for accomplishing efficient energy
management. See Demand Limiting (also called load shedding)
section below and Leaving-Fluid Temperature Reset section on
page 44 for further details.
Demand limiting (also called load shedding) — When a
utility's demand for electricity exceeds a certain level, loads are
shed to keep electricity demand below a prescribed maximum
level. Typically, this happens on hot days when air
conditioning is most needed.
Demand may be limited on unit by resetting fluid
temperature, or by unloading the chiller to a given
predetermined percentage of the load. Demand limit may also
be driven by an external 4 to 20 mA signal. These features
require a signal from an intelligent central control. Do not cycle
demand limiter for less than 10 minutes on and 5 minutes off.
Duty cycling cycles electrical loads at regular intervals
regardless of need. This reduces the electrical operating costs
of building by "fooling" demand indicating devices. Duty
cycling of compressors or fans is not recommended since
motor winding and bearing life suffer from constant cycling.

Remote on-off control

Remote on-off control may be applied by hard-wired
connection (see Controls and Troubleshooting literature) or by
connection to a Carrier Comfort Network (CCN).
Part-wind start
This is not generally required on 30GTN,GBN chillers due to
use of multiple compressors allowing smaller electrical load
increments, but is available
instantaneous current flow (see ICF in Electrical Data table on
pages 78-81) should be used in determining need.
Strainers
It is recommended that a strainer with a minimum of 20 mesh
be installed in the cooler fluid inlet line, just ahead of and as
close as possible to the cooler.
Condenser coil protection
Copper-fin coils provide increased corrosion resistance in
moderate coastal environments where industrial air pollution
is not present. All copper coils eliminate bi-metallic
construction to eliminate the potential for galvanic corrosion.
Application in industrial environments is not recommended
due to potential attack from sulfur, sulfur oxide, nitrogen
oxides, carbon and several other industrial airborne
contaminants. In moderate seacoast environments,
copper-fin coils have extended life compared to standard or
pre-coated aluminum-fin coils.
if required. Maximum
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