Section 1 – Page 7
1.2.1 User Adjustments and Options
The amplifiers each have a personality module that is used to set up the drive for the
application as required. The drive features which are customized by the user on the
personality board include:
Continuous Current limit value
Maximum Speed Range (3000 / 6000 rpm)
Motor pole selection
Calibration adjustments
Limit Switch enable and polarity
Encoder output resolution
The Limit switch inputs and Emulates encoder outputs are standard on the LX, however
these features can be deleted when purchasing quantities of drives to further reduce
costs. See your Emerson Sales Representative for further details.
1.3
Basic Function and Operation
The amplifier is designed to operate in either a velocity command or current (torque)
mode with an analog ±10 volt command. The velocity command input is a true
differential input while the current command input is a single ended input that doubles
as the current demand output. This signal can be used as a master output in torque
helper applications as well as a test point for detecting the actual motor current required
in an application. For details about the current command mode see the “Special
Applications” section 6.
1.3.1 Feedback Signals
Speed and position feedback signals are accurately derived from the position
information coming from the resolver mounted on the motor shaft.
The derived tachometer signal is used by the amplifiers speed control circuitry and is
available as an analog signal output on the connection strip. This tachometer output
provides analog voltage proportional to the shaft speed with a range of ± 10V equal to ±
3000 / 6000 rpm.
Emulated encoder outputs with zero markers are provided on the standard LX amplifier
for use with position controllers.
1.3.2 Control Loops
The LX drive uses two high performance control loops (current and velocity) to control
the speed and torque of the motor. The “current loop” controls the current flowing into
the motor by comparing the current flowing in the motor to the current command from
the reference signal and correcting it to maintain the commanded current. The current
command can come from either an external controller or directly from the LX amplifiers
speed loop. The velocity loop controls the motor velocity by comparing the actual
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