Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 156)

156 Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013
Chapter 1 Detail Drive Configuration and Operation
Start/Stop Modes Description
This section serves as a supplement to the PowerFlex 700S Drive User Manual,
publication
20D-UM001 , addressing items specific to the PowerFlex 700S start
and stop modes.
Technical Information
The start and stop mode refers to how you want the drive's start and stop to be
controlled. There are two basic modes of start and stop control: 3-wire and 2-
wire.
3-wire control indicates that the start and stop are momentary inputs. 3-wire
control also indicates that there is one input for the start command, and one
input for the stop command. The term “3-wire” comes from the fact that when
using this type of control with digital inputs, one wire is used for the start input,
one wire is used for the stop input, and one wire is used for the common.
2-wire control indicates that the start and stop are combined as one maintained
input. The input must be on to start and to remain running. Then the same input
is turned off to stop. The term “2-wire” comes from the fact then when using this
type of control with digital inputs, one wire is used for the combined start/stop
input, and one wire is used for the common.
For the stop command, there are three different types of stopping that can be
performed: coast stop, ramp stop, and current limit stop.
• Coast Stop - when in coast stop, the drive acknowledges the stop
command by shutting off the output transistors and releasing control of
the motor. The load/motor will coast or free spin until the mechanical
energy is dissipated.
• Ramp Stop - when in ramp stop, the drive acknowledges the stop
command by ramping down the motor speed reference using the
programmed parameter 33 [Decel Time], maintaining control of the
motor until the drive output reaches zero. The output transistors are then
shut off.
• Current Limit Stop - when in current limit stop, the drive acknowledges
the stop command by setting the motor speed reference to zero, causing
the drive to bring the motor down to zero speed as fast as the power limits,
torque limits and current limits will allow. When the drive output reaches
zero, the output transistors are shut off.
When different stop types are commanded at the same time, the priority from
highest priority to lowest is coast stop, current limit stop, and then ramp stop.
The remainder of this section describes how to configure the drive for the
different start and stop modes.