User Manual - Series B Instruction Manual

18 Rockwell Automation Publication PFLEX-UM003B-EN-P - July 2012
Description of Operation
Description of Operation
PowerFlex 40P Safe Torque Off Operation
The DriveGuard Safe Torque Off option for PowerFlex 40P (see Figure 8)
disables the drive’s output IGBT’s by breaking the link with the drive
microcontroller. When used in combination with a second safety channel (the
Enable input), the system satisfies the requirements of EN ISO 13849-1,
Category 3 / PL (d) for Safe Torque Off and helps protect against restart.
Under normal drive operation, the Safe Torque Off relay is energized, the
enable input is energized, and the drive is able to run. If either inputs is
de-energized, the gate control circuit is disabled. To meet EN ISO 13849-1,
Category 3 / PL (d) operation, both safety channels must be de-energized.
Refer to the following examples for details.
Figure 8 - PowerFlex 40P Drive Safe Torque Off Circuitry
IMPORTANT
By itself, the Safe Torque Off option initiates a coast-to-stop action. Additional
protective measures will need to be applied when an application requires a change
to the stop action.
+24V DC
PowerFlex 40P
AC Drive
Stop
Start
AC Line
Input Power
Common
Enable
M
Gate Control
From Microcontroller
Gate Control
Circuit
Safety
Channel
Safety
Channel
1
2
3
4
Safe O Option
PFLEX-UM003.fm Page 18 Wednesday, July 18, 2012 8:26 AM