Source : http://www.youtube.com/watch?v=lB3HBoKPbOQ
Saturable reactor or magnetic amplifier is a circuit that used to control very large load of AC with very small input DC. The saturable reactor consists of three essential elements : Direct current source, magnetic core with windings, and alternating current source. How it work? The AC load circuit run on to magnetic core and the DC control circuit is also went on to the same core. Ac current flows through winding and Since this current is alternating, the flux set up in the magnetic circuit loop is constantly changing in magnitude and direction. This means the field builds up to a maximum in one direction, collapses, and builds up to a maximum in the opposite direction DC circuit will cause flux which is which is constant in magnitude and constant in direction. This means the field builds up and remains steady state. The AC flux tends to saturate and then desaturate the core because of its cyclical operation. This results in a changing inductive reactance in the load winding. The DC flux, according to it’s strength, aids or opposes the AC flux in its saturate or desaturate effects in the core. Hence, the DC flux tends to control the AC flux controlling the reactance of the load winding. The use of separate windings on a single core has distinct advantages. Load winding consists of comparatively few turns of heavy wire because of large current requirements of different loads. Control winding Ni consists of many turns of fine wire. Since magnetomotive force depends upon the number of ampere turns, a small current in the control winding produces a magnetomotive force equal to that of the load winding. Usually, DC in the order of milliamperes controls AC in the order of amperes. The following describes the steps in the operation and control of the simple saturable reactor: 1. Zero DC control current in the control loop. Since only AC current is flowing through the load windings, an...
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