Description of All Types
Class 8600 / Refer to Catalog 8600CT9601
Reduced Voltage Starting of Squirrel Cage Motors
A squirrel cage motor draws high starting current (inrush) and produces high starting torque when started at full voltage. While these values differ for different motor designs, for a typical NEMA design B motor, the inrush will be approximately 600% of the motor full load amperage (FLA) rating, and the starting torque will be approximately 150% of full load torque at full voltage. High current inrush and starting torque can cause problems in the electrical and mechanical systems, or may even damage the materials being processed. 
When a motor is started at reduced voltage, the current at the motor terminals is reduced in direct proportion to the voltage reduction, while the torque is reduced by the square of the voltage reduction. If the “typical” NEMA B motor is started at 70% of line voltage, the starting current would be 70% of the full voltage value (that is, 0.70 x 600% = 420% FLA). The torque would then be (0.70)^{2} or 49% of the normal starting torque (that is, 0.49 x 150% = 74% full load torque). Therefore, reduced voltage starting provides an effective means of reducing both inrush current and starting torque. 
If the motor has a high inertia or if the motor rating is marginal for the applied load, reducing the starting torque may prevent the motor from reaching full speed before the thermal overload relays trip. Applications that require high starting torque should be reviewed to determine if reduced voltage starting is suitable. Square D™ offers several types of electromechanical as well as solidstate reduced voltage starters that provide different starting characteristics. The following describes the 8600 series of reduced voltage starters. 
Electromechanical Reduced Voltage Starters
Class 8606—Autotransformer Starter: Autotransformer starters provide reduced voltage to the motor terminals during starting through the use of a tapped, three phase autotransformer. Taps on the autotransformer allow for selection of the motor with 50%, 65%, or 80% of line voltage values supplying 50%, 65%, or 80% of the current inrush seen during a full voltage start. The resulting starting torque will be 25%, 42%, or 64% of full voltage values, as will be the current draw on the line. Thus, the autotransformer provides the maximum torque with minimum line current. 
Class 8630—WyeDelta Starter: Wyedelta starters can only be used on wyedelta motors which have six leads that allow for motor winding to be connected in either a wye or delta configuration. During start up, the windings are connected in the wye, resulting in 58% of line voltage applied across two windings. This reduces both inrush and starting torque to 33% of the delta connected values. After a set time delay, the motor leads are switched to the delta connection. The wyedelta starter is available in both open and closed transition configurations. Closed transition starters are supplied with an additional contactor and resistor bank used to keep the motor windings energized for a few cycles until the transition from wye to delta is complete. 
Class 8640—Part Winding Starter: Part winding starters can be used only with part winding motors. During a part winding start, only one winding is energized, reducing the inrush current to 60–70% (depending on the motor design) and starting torque to 50% of normal starting values with both windings energized. Most (but not all) dual voltage 230/460 volt motors are suitable for part winding starts at 230 volts. 
Specifications
Starter Characteristics
Characteristic 
Full Voltage 
Autotransformer, Class 8606 
WyeDelta Class, 8630 
Part Winding, Class 8640 
SolidState ATS46 

Voltage at Motor 
100% 
50% / 65% / 80% (tap setting) 
100% 
100% 
Ramped Up 
Line Current (% Full Load Current) 
600% 
150% / 250% / 380% 
200% 
390% 
150% to 700% (adjustable) 
Starting Torque (% Rated Torque) 
150% 
40% / 60% / 100% 
50% 
70% 
0% to 100% (adjustable) 
Start Time (Factory Setting) 
— 
6–7 s 
10 s / 15 s (open/closed transition) 
1–1.5 s 
10 s 
Advantages 





Disadvantages 



Not suitable for:


Motor 
Standard 
Standard 
Special 
Special 
Standard 
Line Voltage Codes (60 Hz)
Line 
Control 
Code 

208 240 380 
208 240 380 
V08 V03 V05 
Coil Voltage Codes (60 Hz)
Line 
Control 
Code 

208 240 240 480 480 480 600 380 other 
120 24 120 24 120 240 120 110/50 specify 
V84 V82 V80 V83 V81 V87 V86 V95 V99 
Form Codes
Form Description 
Form Code 

Fused CPT for timing relay only 
F4T 
Fused CPT for all coils 
F4T40 
Separate control of timing relay only 
S 
Separate control for all coils 
Y195 
How to Order
note
Line Voltage Codes (60 Hz) and Coil Voltage Codes (60 Hz) are for 60 Hz; for 50 Hz codes, see Coil Voltage Codes (50 or 60 Hz).

Specify the Class Number and the Type Number.

If all coils are at the line voltage, and not Sizes 6 or 7, select the voltage code from Line Voltage Codes (60 Hz) (Sizes 6 and 7 are supplied with a fused transformer with 120 Vac as standard).

If the coils are at a different voltage than line supply, or Size 6 or 7, select a voltage code from Coil Voltage Codes (60 Hz) and also select a Form code from Form Codes (note that a Form code may be used with any voltage code, except as noted).
See 380 Vac, 50 Hz Starters, Maxiumum Horsepower Rating for sizing of 380 V starters.
24 V coils are not available on Sizes 4–7.
Factory Modifications (Forms): see Factory Modifications (Forms).
380 Vac, 50 Hz Starters
The Class 8600 starters are available for 380 Vac, 50 Hz applications. 380 Vac, 50 Hz Starters, Maxiumum Horsepower Rating provides maximum horsepower ratings. To determine the Type number, select the second digit based on the NEMA size. Select the fifth digit based on the horsepower requirement. Specify V05 voltage code.
380 Vac, 50 Hz Starters, Maxiumum Horsepower Rating
Autotransformer, Class 8606 
WyeDelta, Class 8630 
Part Winding, Class 8640 


Max. hp 
NEMA Size 
Max. hp 
NEMA Size 
Max. hp 
NEMA Size 
— 
— 
15 
1YD 
15 
1PW 
50 Hz Control Voltage
Coil Voltage Codes (50 Hz)
Hz 
V 
Code 
V 
Code 
V 
Code 
V 
Code 

60 
120 
V02 
240 
V03 
480 
V06 
600 
V07 
The starters in this section can also be operated at 50 Hz at the coil voltages listed in Coil Voltage Codes (50 or 60 Hz). For additional coil voltage availability, contact the Customer Care Center (CCC) at 18887782733.