Electrical Installation Design[motor Control Panel Design]

INTRODUCTION Star-delta This method of reduce voltage starting applies only to three phase, delta connected squirrel-cage motors. During starting however, the stator winding will be connected in star so that each phase receives 1/3 of the normal supply voltage. Sub-sequencely the starting current and the starting torque will be reduced in portion to the square of the voltage ratio. Auto transformer starting These are the most widely used reduced voltage starters because of their efficiency and flexibility . basically the starter compromise of a 3 phase auto-transformer on which tapings are provided on the secondary side. Taps on the transformer allow adjustments of the starting torque and in rush current. Direct-online starting Is the simplest and most cost effective, with the motor simply connected to the supply. This method of starting suffers from high current/torque during starting. Due to it’s simplicity it is my preferred method of starting, however, there are many instances where it’s disadvantages make it impractical. Methodology For the this lab assessment we need to design and compare between autotransformer and star-delta and direct online (DOL) starting in term of: a)

Measurement of the distance from one motor control panel to another motor control

panel. b)

Measurement of the distance from main supply to motor control panel.

c)

Measurement of the distance of each indicator lamps, voltage and current

measurement at in front of motor control panel cover. d)

Measure the distance to put the electrical components such as RCCB, MCB, CT,

Timer, Magnetic Contactor, busbar, neutral and ground bar in the motor control panel. e) Measure the cable size used for motors, power cable f) Compare DOL, Star Delta and Autotransformer function

The single line diagram of each starter motor then were being analyze to determine which component will be assembled according to the size of the control panel. The single line diagram of each motor starter can be refer in the figure below:

Figure 1 : Auto Transformer (control circuit)

Figure 2: Direct-on-Line (control circuit) Before start designing each motor starter control panel, the information of each phase value and component used in the control circuit is very important to estimate the size and the space require by each component and also to leave some extra space so that it will be easy to do the maintenance in the future. Type / Phase DOL

Star-delta

Autotranformer

Value RY RB YB

Component used

415 420 418

Phase Star Delta Value(V) Value(V) 243 418 243 420 243 420

Phase Starting(V) 296.6 297.3 298.6

Stable(V) 423 425 424

Component

Type

Manufacture

Spectcation

RCCB

ABB

AC type 4 Pole Rated current:40A

Single Pole and HAGER Switched Netural Fuse Cariers c/w Fuse type gF

Magnetic contactor

Fuji Electric

Timer

CIKACI ELECTRONIC

3-Phase Motor

Induction TECO

Fuse rating: 32A

CONTECT:5A 250VAC

Star-Delta:

Result and discussion After gathering the information about the component, cable size, type of motor used, then only we can start designing the front panel and inside the panel. The panel dimension is, Length= 420mm , width=800mm, height from the floor=1700mm and height from the floor to the working panel(control circuit) is 900mm. While the distance from the panel to the power supply is 2 feet. The front panel and the control panel design can be reffered at the appendix provided.

420mm

800m 1700m

m

m Main supply 900mm

2 feet

Figure 3 : control panel dimension

Conclusion

When designing electric motor control panel, lot of consideration has to be made. http://en.wikipedia.org/wiki/Autotransformer http://en.wikipedia.org/wiki/Y-%CE%94_transform myelectrical.com/opinion/entryid/79/motor-starting-direct-on-line