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14 TRG-TRC010-EN
notes
period one
Components
performance is a system-wide issue, not just a matter of chiller design and
control.
A starter links the chiller motor and the electrical distribution system. Its
primary function is to connect (start) and disconnect (stop) the chiller from line
power—similar to what a switch does for a light bulb. The starter, however,
handles much more current and must have the appropriate interlocks to work
with the chiller control panel and oil pump.
Every electrically driven chiller requires a starter. It must be compatible with the
characteristics of both the compressor motor and the electrical circuitry of the
chiller. There are many types of starters, including star-delta, across-the-line,
auto-transformer, primary reactor, and solid state. A variable-speed drive,
which is used to modulate the speed of the motor during normal operation,
also serves as a starter. Important characteristics to consider when selecting a
starter include first cost, reliability, line voltage, and available current.
The starter may be mounted on, or remotely from, the chiller. Use of a unit-
mounted starter reduces electrical installation costs. It may also improve
reliability and save system design time, since all of the components are pre-
engineered and factory mounted.
Depending on the type of starter selected, there are several options that can
simplify installation. Disconnects allow the starter to be isolated from the
electrical distribution system, and short-circuit protection can be provided
using fuses or a circuit breaker.
Starters
remote-mounted
starter
starter
line power
line power
control power
control power
wiring
wiring
unit-mounted
line power
line power
control power
control power
wiring
wiring
Figure 21
trgtrc010_book.book Page 14 Wednesday, September 1, 1999 10:39 AM