A reactor device comprising: a first and a second yoke core (160, 161) formed by toroidally winding an amorphous ribbon; three stacked magnetic leg cores (140, 142) formed of the amorphous ribbon; and a respective coil (100, 102) wound around each of the stacked magnetic leg cores (140, 142), the three stacked magnetic leg cores (140, 142) are arranged at three places on a circumference of the first yoke core with equal spacing between them, the coils (100, 102) are slidingly fitted around respective stacked magnetic leg cores (140, 142), the second yoke core is disposed atop the stacked magnetic leg cores (140, 142), characterized in that the first yoke core is disposed in a circular bottom fastening fixture, and the second yoke core is capped with a circular top fastening fixture, three studs are arranged around the circular bottom fastening fixture and the circular top fastening fixture with equal spacing between them and a central stud is disposed at the center of the circular bottom fastening fixture, and the circular bottom fastening fixture and the circular top fastening fixture are fastened and fixed by means of the studs (90, 91), wherein the reactor device further comprises a coil metal fixture for fixing the coils (100, 102) comprising a metal plate having a predetermined width which is radially extending from the reactor center in three different directions defining an equal angular spacing of 120° therebetween and folded at the predetermined width in each of the three different directions so as to define an L-shape extending into a gap between each of the stacked magnetic leg cores (140, 142) and each of the coils (100, 102), the three coils being mounted to the coil metal fixture, the coil metal fixture centrally comprising a central stud hole for the central stud, and the coil metal fixture being mounted on the central stud. a first and a second yoke core (160, 161) formed by toroidally winding an amorphous ribbon; three stacked magnetic leg cores (140, 142) formed of the amorphous ribbon; and a respective coil (100, 102) wound around each of the stacked magnetic leg cores (140, 142), the three stacked magnetic leg cores (140, 142) are arranged at three places on a circumference of the first yoke core with equal spacing between them, the second yoke core is disposed atop the stacked magnetic leg cores (140, 142), characterized in that the first yoke core is disposed in a circular bottom fastening fixture, and the second yoke core is capped with a circular top fastening fixture, three studs are arranged around the circular bottom fastening fixture and the circular top fastening fixture with equal spacing between them and a central stud is disposed at the center of the circular bottom fastening fixture, and the circular bottom fastening fixture and the circular top fastening fixture are fastened and fixed by means of the studs (90, 91), wherein the reactor device further comprises a coil metal fixture for fixing the coils (100, 102) comprising a metal plate having a predetermined width which is radially extending from the reactor center in three different directions defining an equal angular spacing of 120° therebetween and folded at the predetermined width in each of the three different directions so as to define an L-shape extending into a gap between each of the stacked magnetic leg cores (140, 142) and each of the coils (100, 102), the three coils being mounted to the coil metal fixture, the coil metal fixture centrally comprising a central stud hole for the central stud, and the coil metal fixture being mounted on the central stud.