Trane Starters Engineering Bulletin page 39

8. The S contacts open to open the autotransformer circuit.
9. The autotransformer is now connected as a series reactor with the motor.
10. Now, a secondT interlock and a second S interlock both close to energize the run contactor (2M).
11. The 2M contacts close to bypass the transformer and connect the compressor motor directly
Figure 31. Simplified autotransformer wiring diagram
F
F
Standard features
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Environmental specification
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CTV-PRB004-EN
to the line.
LINE
VOLTAGE
AUTO-TRANSFORMER
1M OL
1M
OL
1M
OL
CPT
START-
STOP
PR T 2M
S
1M
TRANSITION
T S
Control-power transformer
Primary and secondary current transformers (CTs)
Potential transformers (PTs)
Grounding provisions
Bolted line-power connections
Bolted load-side connections for remote starters
Standard motor protection
Designed, developed, and tested in accordance with UL 347
NEMA 1 enclosure as standard
Operation from sea level to 6,000 ft (1,829 m)
Operating ambient temperature range 32°F to 104°F (0°C to 40°C)
• Relative humidity, non-condensing 5% to 95%
Non-operating ambient temperature range -40°F to 158°F (-40°C to 70°C)
Voltage utilization range ±10%
Medium-Voltage Starter Types (2,300–6,600 Volts)
2M
S
S
2M
MOTOR
50% 80%
100%
65%
PR
S
1M
T
2M
39