Rockwell Automation 20D-P2-DG03 DriveGuard Safe Torque Off Option for PowerFlex 700S Phase II and 700L Drives - Manual (Page 29)

Rockwell Automation Publication 20D-UM007G-EN-P - March 2012 29
Chapter
3
Description of Operation
DriveGuard Safe Torque Off Operation
The DriveGuard Safe Torque Off option disables the drive’s output IGBT’s by
disconnecting the gate control power supply (see
Figure 1 ). When used in
combination with a second safety channel (the Enable input), the system
satisfies the requirements of EN ISO 13849-1, PL d / Category 3 for safe turn
off of torque-producing energy at the output of the drive.
Under normal drive operation, the Safe Torque Off relay is energized, the
enable input is energized, and gate control power is available to the gate
control circuit. If either of these inputs is de-energized, the gate control circuit
is disabled and the STS (Status) indicator on the drive will change to a yellow
flashing light. When the enable input is de-energized, parameter 156 [Start
Inhibits], bit 1 “No Enable” is set to “1.” When the Safe Torque Off relay is
de-energized, parameter 156 [Start Inhibits] bit 16 “GateShutDown” is set to
“1.” If both inputs are de-energized, only bit 1 “No Enable” will be set to “1”
because it takes precedence.
To meet EN ISO 13849-1, PL d / Category 3 operation, both safety channel
inputs to the drive must be de-energized to safely turn off output to the
motor. Refer to the following examples for details.
IMPORTANT The DriveGuard Safe Torque Off option does not eliminate dangerous
voltages at the drive output. Input power to the drive must be turned
off and safety procedures followed before performing any electrical
work on the drive or motor.
ATTENTION: In the event of the failure of two output IGBTs in the
drive, when the DriveGuard Safe Torque Off option has controlled the
drive outputs to the off state, the drive may provide energy for up to
180° of rotation in a 2-pole motor before torque production in the
motor ceases.
ATTENTION: By itself, the DriveGuard Safe Torque Off option initiates
a coast-to-stop action. Additional protective measures will need to be
applied when an application requires a different stopping action.