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Mercury rectifier on display in the Beromünster AM transmitter in Switzerland, before being decommissioned.Three-phase full-wave rectifier with six anodes. A mercury-arc valve or mercury-vapor rectifier or (UK) mercury-arc rectifier [1] [2] is a type of electrical rectifier used for converting high-voltage or high-current alternating current (AC) into direct current (DC).
The characteristics and components of ripple depend on its source: there is single-phase half- and full-wave rectification, and three-phase half- and full-wave rectification. Rectification can be controlled (uses Silicon Controlled Rectifiers (SCRs)) or uncontrolled (uses diodes). There is in addition, active rectification which uses transistors.
As with single-phase rectifiers, three-phase rectifiers can take the form of a half-wave circuit, a full-wave circuit using a center-tapped transformer, or a full-wave bridge circuit. Thyristors are commonly used in place of diodes to create a circuit that can regulate the output voltage. Many devices that provide direct current actually ...
Active full-wave rectification with two MOSFETs and a center tap transformer. Replacing a diode with an actively controlled switching element such as a MOSFET is the heart of active rectification. MOSFETs have a constant very low resistance when conducting, known as on-resistance (R DS(on)). They can be made with an on-resistance as low as 10 ...
Phase-Angle Control: Various circuits exist to implement a phase-angle control on different waveforms, such as half-wave or full-wave voltage control. The power electronic components that are typically used are diodes, SCRs, and Triacs.
The Vienna Rectifier is useful wherever six-switch converters are used for achieving sinusoidal mains current and controlled output voltage, when no energy feedback from the load into the mains is available. In practice, use of the Vienna Rectifier is advantageous when space is at a sufficient premium to justify the additional hardware cost.
The current in the TCR is varied from maximum (determined by the connection voltage and the inductance of the reactor) to almost zero by varying the "Firing Delay Angle", α. α is defined as the delay angle from the point at which the voltage becomes positive to the point at which the thyristor valve is turned on and current starts to flow.
When the line voltage falls below the peak, into the "valley" phase, Vout begins to fall toward half of the peak line voltage. At this point, C1 and C2 begin to discharge into the load at Vout, via D1 and D2 respectively. R1 is needed to prevent a large in-rush current, and electromagnetic interference (EMI). [1]