T-Phi Network (Star-Delta) Using Relays and Timer
1. Introduction
In electric circuit star and delta circuit consist of 3 loads which in star circuit they are connected in form of a star while in delta circuit are connected in delta form as in Figure 1.
The application is usually used in (Alternate Current) AC motor where it has to start slowly. Starting the motor through a high current immediately could blow the motor as the starting current equals to the normal current multiplied by v3 (=v3 x I). It’ll be fine if the current is 5A (ampere) (I_start=v3 x 5 A=8.66 A), what happens if it’s 50A it’ll be (I_start=v3 x 50 A=86.6 A). The difference between 50A and 86.6A is quite significant. Therefore a switch to initially start a motor through star condition (low current) is needed, then after a while controlled by a time change the circuit to delta (high current). Full diagram can be seen in Figure 2.
2. Simulation Design
For the experiment here we have limited resource, we don’t have the star-delta motor which made me think whether there’s an alternative to do the star-delta motor simulation. I got an idea of using a low voltage lamp or LED as an indicator by using the brightness of the lamp. Instead I’d use 3 resistors (1 K? for this experiment) to form both star and delta circuit. We’ll see the brightness of…
