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l'h.e total system can be divided into four parts (see J:':lgure 2 .... 4).
The four parts are:
command and logic, regulator, power conver-
sion module and the AC drive motors.
The following is a brief
description of the function of each major portion of the four
parts of the system.
2.3.3.1
Command and Logic Circuitry
The command and logic circuitry is responsible for the
starting or stopping of the system, providing the pro-
tective logic and the manual run control plus the auto-
matic transfer between drive systems.
The selection of
mode of operation (manual or automatic) is also included.
2.3.3.2 Regulator
The regulator's job is to receive an input signal from
either the sensor or the manual speed control and pre-
pare it as a command signal to the power conversion unit.
Its other functions include system response, stability
and power conversion module protection in the form of
current limiting.
2.3.3.3
Power Conversion Module
The power conversion module's task is to deliver the
proper amount of voltage to the motor, based on the
commands received from the regulator, to cause the motor
to drive at the correct speed corresponding to the re-
quired torque.
2.3.3.4 AC Motor(s)
The "KXA" AC motor's task is to drive the pump as
commanded by the sensor or manual control input with
the motor drive power supplied from the power conver-
sion module.
The "K" AC motor
is
a constant speed motor that comes
on (auto mode) when the KXA motor cannot satisfy the
sensor demand.
As
the "K" motor comes up to speed, the
KXA motor decreases speed until the sensor demand is
satisfied.
For a more detailed explanation of system theory of
operation, see Appendix, Section IX.
2-3
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