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CTV-PRB004-EN
Medium-Voltage Starter Types (2,300–6,600 Volts)
Other options for remote-mounted starters are available in the Enhanced Electrical Protection
Package (see
“Industrial-Grade Starters,” p. 63
.)
NEC 2005 changes for medium-voltage (2,300–6,600 volt) wire
NEC code for 2005 requires that medium-voltage cable is shielded. This affects the power wire
selection and connection provisions to the chiller, and between the chiller and starter when it is
remote mounted. When you use shielded cable, you must also use stress cones at the termination
points (motor terminal connection, remote starter, or unit-mounted starter connection). Stress
cones are composed of electrical shielding wrap and are typically 9–12 inches in length. Stress
cones are used to confine the dielectric field and reduce electrical stresses at the termination point.
Trane
®
unit-mounted medium-voltage starters now ship with a field-installed accessory “top hat”
that is shown in our as-built submittal drawings. The
top hat
is enclosed in the starter cabinet
during shipment and then reversed for field installation. Motor terminal boxes and remote-
mounted starters are designed to accommodate stress cones without an additional enclosure.
Refer to the appropriate submittals drawings to verify that the starter has sufficient connection
space for your requirements. For more information regarding the
top hat
, refer to
“Unit-Mounted
Starter Top Hat—NEC 2005 Code Requirement,” p. 40
.
Medium Voltage—Across-the-Line (2.3–6.6 kV)
Across-the-Line Starter (2,300–6,600 volts)
Figure 23, p. 33
shows a schematic for the most basic starter type; the across-the-line (X-Line)
starter, which is also known as a full-voltage starter.To illustrate a typical starting sequence using
a generic (non-Trane) schematic, refer to
Figure 23, p. 33
and the starting sequence below.
Starting sequence
1. A “start” signal from the chiller controller energizes the pilot relay (PR).
2. The PR contacts close to energize the start/run contactor (1M).
3. The 1M contacts close to connect the compressor motor directly to the line.
CTV-PRB004.book Page 32 Sunday, December 18, 2011 6:39 PM
