Understanding Rectifiers and Their Circuits on Ships
Despite their small size, all electrical and electronic equipment and circuits on a ship play a vital role in the operation of its systems and machinery. Various shipboard devices use alternating current (AC), direct current (DC), or a combination of both, depending on their operational requirements. Some of the most critical circuits and configurations use DC.
Since most ships use generators to produce AC power, rectifiers and transformers are necessary to convert AC to DC for use by DC devices or circuits.
A rectifier is a circuit that uses one or more semiconductor diodes to convert alternating current (AC) into pulsating direct current (DC). This conversion process is called “rectification.”
Types of Rectifiers
Half-Wave Rectifiers
A half-wave rectifier consists of a diode connected in series with a load resistor.
During the positive half-cycle of the input voltage, the diode is forward-biased and conducts for all voltages above its barrier voltage.
During the negative half-cycle, the diode is reverse-biased and therefore does not conduct current.
Full-Wave Rectifier
A full-wave rectifier circuit allows current to flow in one direction to the load throughout the entire input cycle.
There are two types of full-wave rectifiers:
1) Two diodes connected in parallel with a center-terminal transformer.
2) A full-wave bridge rectifier, consisting of four diodes connected in a bridge configuration.
Bridge Rectifier
A single-phase bridge rectifier uses four diodes connected in a bridge configuration and is connected without a center transformer. Full-wave rectifiers convert the AC input signal to DC, thereby improving efficiency.
A three-phase rectifier circuit consists of six diodes, arranged in pairs in series (anode-to-cathode). This type of rectifier is commonly used in three-phase circuits.
Marine Applications
Some uses of rectifiers on ships include:
- Used in many marine electronic devices and circuits.
- Used to charge shipboard batteries from the power grid.
- Used to detect radio signals.
- Used in electroplating processes.
- Used in the electrolytic refining of metals in the shipbuilding industry.
- Used for starting DC motors.
- Used for the excitation of three-phase generators.
You may also be interested in: Operational Amplifiers (OPAs) and Electrical Safety Devices: Automatic Circuit Breakers (ACBs).
