Rockwell Automation 1391 USER MNL/DIGITAL AC SERVO DR - Manual (Page 26)

Chapter 4
Description of Operation
4-5
Microprocessor Control The 1391-DES is controlled by an 80C196KB microprocessor. Velocity
control, sequencing, fault logic, programming and option control is
performed by the processor. Current control is analog, as is the input
velocity command. The input command is fed through a 14 bit digital to
analog converter (13 bits/8192 resolution and a +/– sign bit).
Isolated Current Sensing The Logic Control Boards receive current feedback from the Isolated
Current Sense Board. This circuitry provides the data used for current loop
closure.
Integral Circuit Breaker The DC bus supply, input rectifier and power circuitry are protected against
overcurrents by an integral three pole magnetic circuit breaker. This is not
designed nor intended to meet NEC branch circuit requirements.
Line/DB Contactor The three-phase incoming AC line is opened by the contactor whenever the
voltage on the contactor coil is removed. This operation in conjunction
with the shunt regulator reduces the bus voltage when the contactor is
disabled. The Logic Control Board remains energized except when voltage
is removed from the incoming isolation transformer.
Important: The 1391-DES contains a definite purpose contactor that is not
to be energized/de-energized more than twice an hour on a continuous
basis. The life of the contactor may be reduced considerably if the cycle is
exceeded. Contact your local Allen-Bradley Sales Representative for
additional information.
Power Driver Board The Power Driver Board contains the circuitry needed to switch the power
transistor modules.
A Quad B Board The A Quad B Board changes the resolver signal from a 1326AB or AD
motor into an encoder signal for use by a position controller (such as an
IMC S Class or 12x family controller).
Starting and Stopping
ATTENTION: The Enable control circuitry in the 1391-DES
includes solid-state components. If hazards due to accidental
contact with moving machinery or unintentional flow of liquid,
gas or solids exist, an additional hardwired stop circuit may be
required. Refer to the codes and standards applicable to your
particular system for specific requirements and additional
information. A device that removes AC input power when a
stop is initiated is an integral part of this drive. Refer to the
following individual stop mode explanations.
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