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CTV-PRB004-EN
Medium-Voltage Starter Types (2,300–6,600 Volts)
Medium Voltage—Remote-Mounted Adaptive Frequency Drive
The Trane AFD is a remote-mounted air-cooled, microprocessor based pulse width modulation
PWM design.The AFD use a “direct to drive” design that connects the power supply directly to the
medium voltage drive with out the use of an isolation transformer. The AFD is a current source
inverter that uses Symmetrical Gate Commutated Thyristors (SGCTs) power semi-conductor
switches in both the rectifier and inverter sections.The active front end rectifier and common mode
choke blocks any common mode voltages, smooths the DC current, and mitigates the motor neutral
to ground voltage. Because there is no negligible common mode voltages and currents, no special
compressor bearing provisions are required.The design does not generate dv/dt or reflected wave
voltage that can stress the motors. As a result, standard duty medium voltage motors can be used
with the AFD.
The AFD includes a line starter contactor and current limiting power fuses and a lockable non-load
break isolation switch as standard.The fuses are installed via fuse clips and can be replaced without
special tools. An integral common mode choke with iron core eliminates the need for semi-
conductor fuses which reduce nuisance trips. The AFD ships as a single, free-standing enclosure
(with a small exception of small top hat sections), wired, and tested to the job site.
Remote AFD Design Features
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NEMA 1 ventilated, gasketed enclosure with hinged doors.
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Design access from the front only. The patented PowerCage inverter and rectifier module
allows easy access to main power components without the use of special hardware. Power
switch components are replaceable without removal of the entire power module.
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Paint—All exterior metal parts are painted with hybrid epoxy powder paint ANSI 49 medium
grey. The low voltage section is color coded black for safety.
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The entire package is UL/CUL listed.
Other AFD features include:
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Simple modular design.
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Compact, light weight design.
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Designed for minimum availability of 99.9 percent.
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Typical mean time between failure is 180,000 hours.
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Minimum predicted life expectancy is 20 years.
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The AFD is rated for the nominal chiller voltage ±10 percent.
Figure 33. Front view, medium voltage remote-mounted AFD
CTV-PRB004.book Page 42 Sunday, December 18, 2011 6:39 PM