Switch-Mode Power Supply
The computer-controlled switch-mode power supply consists of two major sections: The computer controller and the power supply.
The computer controller continuously monitors the protection level of
the immersed hull areas. This information is processed in order to
determine how much output current is required. Once determined, the
power supply output is adjusted by the computer for the optimum level
of protection.
The power supply section derives its power from the ship's
generated AC supply. This input voltage is stepped down and rectified
by the switcher. The filtered DC output is regulated by the computer
and switch-mode power supply circuits.
Hull-mounted zinc reference electrodes provide an
input signal to the computer. This input signal corresponds
directly to the level of current required to protect the immersed hull areas.
A vacuum fluorescent display indicates power output in amps
and volts. This display also indicates the reference electrode
potential and shaft-hull potential in millivolts.
The computer controller consists of a motherboard and daughterboard located on the I/O panel which also contains all anode
and cell terminals. The computer is microprocessor-based and pre-programmed to
entirely control all functions of the power supply under the many
adverse operating and environmental conditions which may be encountered.
A computer is utilized because of its flexibility in
operating modes, high reliability, accuracy and user convenience. In
the marine environment, it is sometimes difficult and often expensive
to arrange for service calls. The computer has no adjustments to be
made, tests itself and calibrates itself, thus making it truly automatic.
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