ac switch instead of a standard circuit breaker or contactor more precise control can be obtained over the point in wave i e phase angle that the switch turns on and off this improves the control of the system with the hil grid simulator interface controller here the reactive divider network 640 is operative so as to deliver or receive power from power amplifier bus 140 to grid simulator bus 180 as further illustrated in fig6 fig5 indicates that power flows through tapped resistor 642 and tapped inductor 644 which form part of the series impedance the scr series bypass switch 646 connects between the reactive divider network point of common coupling 655 and power amplifier bus 140 breakers 650 a 650 b 650 c and 650 d connect the reactive divider network point of common coupling 655 to the junction points of the series connected bank of inductors 648 a 648 b and 648 c by selection of the open close position of breakers 650 a 650 b 650 c and 650 d inductors 648 a 648 b and 648 c can be moved to either the series impedance the shunt impedance or bypassed with switch 650 a shown as open in fig5 current must flow through fixed inductance 648 a which forms the rest of the series impedance and through 650 b to the reactive divider network point of common coupling 655 if.