HP Type F02 manual Auto Transformer Starter, Wye Delta Starter, Part Winding Starter, Operation

Page 23

AC Controls

Reduced Voltage Starters — Electromechanical

General

Auto Transformer Starter

Operation

At starting, the auto transformer reduces motor terminal voltage to 50, 65, or 80 percent of line voltage. For a timed inter- val, a segment of the transformer coil is connected in series (as an inductor) with the motor. Then a contactor automatically connects the motor across the line and shorts out the inductor.

Wye Delta Starter

Operation

Initially the starter connects the motor on a Wye connection, reducing voltage across the winding to approximately

58 percent. Starting torque and current is about 33 percent of across the line. After a time delay the motor is connected Delta.

Part Winding Starter

Operation

Part winding starters apply starting current in timed steps to part winding motors. Two step controllers apply volt- age through one starter to one motor winding followed by the second starter which connects voltage to the second winding. The timer may be adjusted to automatically close the second controller at the most favorable time to minimize voltage fluctuations.

Auto Transformer Starter

Wye Delta Starter

Part Winding Starter

Typical Speed Torque Curves

15

AC Controls

Table 15.35 Comparison of Various Electromechanical Methods of Reduced Voltage Motor Starting

 

Reduced Voltage Starting

 

 

Autotransformera

Part Winding

 

 

50%

65%

80%

 

 

Characteristics

Tap

Tap

Tap

2 Step

Wye(Star) Delta

Starting current drawn from line as % of

 

 

 

 

 

that which would be drawn upon full

25%

42%

64%

64%c

33%

voltage starting b

 

 

 

 

 

Starting torque developed as % of that

Increased slightly with

45%c

33%

which would be developed on full

speed

 

 

voltage starting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Smoothness of acceleration d

First in order of

 

Third in order of

Second in order of

 

smoothness

 

smoothness

smoothness

Allowable accelerating times (typical)

30 seconds

 

2-3 seconds

45-60 seconds

 

Based on NEMA

 

 

 

Limited by

Limited by

 

medium duty

 

 

 

motor design

motor design

 

transformers

 

 

 

 

 

 

 

 

 

 

 

aClosed Transition.

bFull voltage start usually draws between 500% and 700% of full load.

cApproximate values only. Exact values may be obtained from motor manufacturer. d Solid state starters provide the smoothest starting characteristics.

306

Siemens Electrical Products and Systems

CSI Section 16160

Specification Guide

 

 

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Contents General Manual Starters and SwitchesTypical Wiring Diagrams AC Controls Class SMF Heater Elements Horsepower RatingsManual Starters and Switches Features General Purpose Flush Mounting for Two Unit Devices DimensionsGeneral Purpose Flush Mounting Two Unit Devices Nema Type 1 General Purpose EnclosureDimension / Wiring Diagrams Manual Motor Starter SwitchesManual Motor Starter Protector General / Dimensions3VU13 Enclosure Dimensions Technical DataClass 11 Manual Motor Starters General / Wiring DiagramsManual Motor Starters and Contactors Motor Starters 14 Reference Literature Magnetic ContactorsApplications Coil DataLighting and Heating Contactors 21WE 2-12 Pole 21 2-12 Pole DimensionsWiring Diagrams Typical Compact Magnetic Contactors LightingCLM Contactors 300 and 400 Amperes, 2- and 3-Pole Ballast Load Combination Lighting and Heating FeaturesDescription Magnetic Latch OperationCombination Starters Nema Sizes DimensionsContactors Non-Reversing Key Features27 Contactor Technical Data Starters Key Features Cont’dMagnetic Motor Starters Full Voltage Non Reversing Size 0 through Magnetic Motor Starters-Full Voltage Non ReversingAuxiliary Equipment Sizes 2-31/2 Pole 3 Phase Magnetic Contactors Size 4 1/ 2 Dimensions / Wiring DiagramsContactor Dimensions Pole Single Phase Magnetic Contactors SizeEnclosures Enclosure Dimensions303 Ratings Full Voltage, Non-Reversing Starters Nema SizesCombination Multi-Speed Starter Torque Characteristics33 3-Phase Multi-Speed Starter Multi-Speed Starters Nema SizesOperation Auto Transformer StarterWye Delta Starter Part Winding StarterPump Stopa Phase LossSolid-State Reduced Voltage Starters Shorted SCRa36 Solid-State Reduced Voltage Starters Pilot Device Units Pilot Device Units and Indicator Lights Type 3SBOEnclosed Pilot Device Stations Enclosed Pilot Device StationsSpecifications Guide Form SpecificationsReduced Voltage, Part Winding Starters Reduced Voltage Autotransformer StartersMulti-Speed Starters Reduced Voltage Wye Delta Starters
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