Powerohm Products

Standard Motor Control Designs

WYE-DELTA TYPE STARTERS (CLOSED TRANSI TION): In the case of a wye-delta closed transition type starter, a set of resistors is connected to the motor winding before the delta contactor is closed. These resistors are used to balance the back EMF of the motor and the line voltage before closing the delta contactor. Closed transi tion eliminates the surge current that occurs when trans ferring the motor from wye to delta connection, thus providing a smoother acceleration of the motor from reduced voltage to full voltage. WYE-DELTA STARTING RESISTORS Data Requirements: - Horsepower - Full Load Amps - Normal Line Voltage

Motor

R R

R

Typical Control Schematic for a Wye-Delta Starter (Closed Transition)

OHMS PER PHASE CATALOG NUMBER RESISTOR DESIGNS FOR WYE-DELTA STARTERS (CLOSED TRANSITION) CATALOG NUMBER MOTOR H.P. MOTOR AMPS MOTOR AMPS MOTOR H.P.

OHMS PER PHASE

230 VOLTS WD230-10 WD230-15 WD230-20 WD230-25 WD230-30 WD230-40 WD230-50 WD230-60 WD230-75 460 VOLTS WD460-10 WD460-15 WD460-20 WD460-25 WD460-30 WD460-40 WD460-50 WD460-60 WD460-75

380 VOLTS WD380-10 WD380-15 WD380-20 WD380-25 WD380-30 WD380-40 WD380-50 WD380-60 WD380-75 575 VOLTS WD575-10 WD575-15 WD575-20 WD575-25 WD575-30 WD575-40 WD575-50 WD575-60 WD575-75

10 15 20 25 30 40 50 60 75 10 15 20 25 30 40 50 60 75

28 42 54 68 80

4.70 3.20 2.50 1.90 1.70 1.30 1.00 0.85 0.70 0.55

10 15 20 25 30 40 50 60 75 10 15 20 25 30 40 50 60 75

17 25 33 41 48 63 79 93

13.00 8.60 6.70 5.30 4.50 3.50 2.80 2.40 1.90 1.50 30.00 19.50 15.00 12.30 10.40 8.10 6.40 5.40 4.30 3.40

104 130 154 192 248

116 150

WD230-100

100

WD380-100

100

14 21 27 34 40 52 65 77 96

19.00 12.70 9.90 7.80 6.60 5.10 4.00 3.50 2.80 2.10

11 17 22 27 32 41 52 62 77 99

WD460-100

100

124

WD575-100

100

CONSTRUCTION: Formost applications, the resistorsare mounted in the upper section of the motor control cabinet. Therefore, all of theabovestandarddesignsconsist of three WR Type resistor coils mounted on open style Type B3 brackets. These brackets have a mill galvanized finish.

FRONT VIEW

SIDE VIEW

9"

7/16" DIA.

8-1/2" 9-1/2"

3"