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*Instructions are at the bottom*
This circuit represents a Y/∆ starter pack for electric motors. A Y/∆ starter is used for motors which have higher power (kW). Normally, when a electric motor is started, it's peak current will be around 6 to 8 times In (nominal current). So when a motor has a In of 4 A, the peak current will be around 24 to 32 A. When a motor has a In of 30 A, this will be around 180 to 240 A! To reduce peak current during start up, a Y/∆ starter is used. Due to the fact, that when a motor wired in ∆ circuit, the current which flows through a coil, is the total current per phase ÷ √3, due to the effect that each phase delivers current to 2 coils. In the case of this simulation, when the "motor" (the 3 lamps) is wired in ∆, the current per phase is 30 A, but the current per coil is 17,3 A. When starting up in Y, the voltage will be 400 V ÷ √3, due to the created starpoint. Which means the voltage is 230 V. So the current through the coils will again be reduced (current when wired in ∆ ÷ √3). This means that the current through the coils will be 30 ÷ 3 (√3 × √3 = 3) = 10 A. 10 A times the peak (6 to 8 times In) will be 60 to 80 A. So, instead of 180 to 240 A during startup, the peak current will be 60 to 80 A. Thanks to the Y/∆ circuit.
How to use:
Make sure both switches are opened.
Close the left switch, This will close the mains contactor, and the Y/∆ change over contactor will be on Y.
Look at the currents through the 2 selected coils, and phase L1.
Then close the right switch. This will change over the Y/∆ contactor to ∆.
Look at the currents and see the differences.
When switching off the circuit: open the left switch, and then the right switch. The next time, the "motor" will startup again in Y.
Note: the "ground" on the rotor part, is done because the circuit wouldn't work without it. In a real circuit, the rotor wouldn't be grounded.
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