Low Voltage—Wye-Delta. Trane Drives, CVHG, Starters, CVHF, Electrical Components, CVHE, CDHG, CDHF

CTV-PRB004.book Page 18 Sunday, December 18, 2011 6:39 PM

Low-Voltage Starter Types

Figure 6.

Comparison of low-voltage starting current

120

100

80

60

40

20

0

0

X-Line

Solid-State

Wye-Delta

AFD

1 2 3 4 5

Time (seconds)

6 7 8 9 10

Low Voltage—Wye-Delta

Wye-Delta Starters

One of the most common starters in the industry is the wye/star-delta. It is an electromechanical starter initially set up in a “wye” or “star” configuration, then it transitions to a “delta” configuration during the starting sequence.To illustrate a typical starting sequence using a generic

(non-Trane) schematic, refer to Figure 7, p. 19 and its “Starting sequence,” p. 19 .

18 CTV-PRB004-EN

CTV-PRB004.book Page 19 Sunday, December 18, 2011 6:39 PM

Low-Voltage Starter Types

Figure 7.

Simplified wye-delta wiring schematic

LINE

VOLTAGE

WYE-DELTA

STARTER WIRING

CTV-PRB004-EN

F

OL

OL

OL

1M

2M

1M

2M

1M

2M

R 1A

S

R 1A

S

R 1A

S

MOTOR

CPT

F

START-

STOP

PR 1A 2M

S

1M S

TRANSITION

PR

S

1M

2M

1A

Starting sequence

1. The “start” signal from the CenTraVac controller energizes the pilot relay (PR).

2. The PR contacts close to energize the star contactor (S).

3. The S contacts close to connect the motor in the star configuration.

4. An S interlock closes to energize the start contactor (1M).

5. The 1M contacts close to connect the motor to the line.

6. A time delay relay or current monitoring device initiates transition by energizing the resistor contactor (1A).

7.

1A contacts close to connect the resistors to the line in the star configuration and in parallel with the compressor motor.

8. A 1A interlock now opens to de-energize the S contactor.

9. The S contacts open to connect the resistors and motor windings in series in the delta configuration.

10. An S interlock closes to energize the run contactor (2M).

11. The 2M contacts close to bypass the resistors and connect the compressor motor directly to the line in the delta configuration.

Dimensions

The typical unit-mounted wye-delta starter size is shown in Figure 9, p. 20 . Typical remotemounted one-, two- and three-door starter sizes are shown in Figure 10, p. 20 , Figure 11, p. 20 , and

Figure 12, p. 21 . Always consult the submittal drawings for as-built dimensions.

19

CTV-PRB004.book Page 20 Sunday, December 18, 2011 6:39 PM

Low-Voltage Starter Types

The one-door remote-mounted starter size is generally used for 155- to 606-amp starters with no disconnect.The two-door size is used for 640- to 1,700-amp starters with no disconnect.The threedoor size is used for 1,385- to 1,700-amps when disconnects are included.

Figure 8.

Unit-mounted WD Figure 9.

Remote 1-door WD

Squirrel-cage

Stator

60”

Rotor shaft

13.5”

38.5”

84”

Stator

19.3”

32”

Figure 11. Remote 3-door WD Figure 10. Remote 2-door WD

Stator

Squirrel-cage

84”

Rotor shaft

84”

Stator

19.3” 19.3”

56”

84”

20 CTV-PRB004-EN

CTV-PRB004.book Page 21 Sunday, December 18, 2011 6:39 PM

Low-Voltage Starter Types

Figure 12. Unit-mounted, wye-delta starter

2

1

2

1. Top-entry power only

2. 4 kVA control-power transformer

3. Circuit breaker (optional)

4. Transition resistors

3

CTV-PRB004-EN

4

Standard features

• Unit or floor mounted

• Control-power transformer

• Padlock tab for additional locking of the starter door

• Line-side connection terminal block/main lug only

• UL and CUL certified

• Environmental specification

• Designed, developed, and tested in accordance with UL 508

• 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 percent to 95 percent

• Non-operating ambient temperature range -40°F to 158°F (-40°C to 70°C)

• Voltage utilization range ±10 percent

21