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Page 321

| Figure 16-8 Connections for six-phase rectifier: (A) Standard six-phase connection, and (B) double three-phase connection. |

| In three-phase or six-phase rectifiers (Fig. 16-8) under normal operating conditions, conduction will shift from one anode to another so that current flow will be maintained. |

| In single-phase rectifiers (Fig. 16-9), the current drops to zero twice in a cycle, and an auxiliary set of anodes is provided. These anodes are connected to a supply voltage in series with an inductance. The inductance makes the current lag the voltage so that conduction will be maintained by the auxiliary set until the regular anode can continue on from the zero point of the cycle. This arrangement is sometimes known as the keep alive circuit. |

| Since the ionized mercury permits current to flow in only one direction, only half the ac cycle flows through the rectifier. A second rectifier, with polarity reversed, can be used to permit both halves of the cycle to be converted to dc. The dc voltage thus produced will be serrated. Its sharp peaks can be smoothed somewhat by placing a reactor in the circuit. Further smoothing can be obtained by using a three-phase supply that will produce dc from six |

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