Rockwell Automation 20C-DG01 PowerFlex 700H AC Drive Safe Torque Off Option - Manual (Page 7)

Rockwell Automation Publication 20C-UM001B-EN-P - June 2011 7
Chapter
1
Overview
The PowerFlex 700H control board, 24V DC Digital Input with Analog I/O
(20C-DA1-A) board, and the Safe Torque Off option board (20C-DG01), when
used with other safety components, helps provide a hardware-based safe torque
off to prevent torque on the motor shaft.
The Safe Torque Off option is just one component in a safety control system.
Components in the system must be chosen and applied appropriately to achieve
the desired level of operator safeguarding.
What is the Safe Torque Off
Option? The Safe Torque Off option is designed to safely remove power from the gate
firing circuits of the drive’s output power devices (IGBT’s). This helps prevent
the drive’s output power devices from switching in the sequence necessary to
generate torque in the motor.
IMPORTANT This option is suitable for performing mechanical work on the drive
system or affected area of a machine only. It does not provide electrical
safety.
This option should not be used as a control for starting and/or stopping
the drive.
ATTENTION: Electrical Shock Hazard. Verify that all sources of AC and DC
power are de-energized and locked out or tagged out in accordance with
the requirements of ANSI/NFPA 70E, Part II.
ATTENTION: To avoid an electric shock hazard, verify that the voltage on
the bus capacitors has discharged completely before servicing. Check the
DC bus voltage at the Power Terminal Block by measuring between the +DC
and -DC terminals, between the +DC terminal and the chassis, and
between the -DC terminal and the chassis. The voltage must be zero for all
three measurements.
ATTENTION: In Safe Torque Off mode, hazardous voltages may still be
present at the motor. To avoid an electric shock hazard, disconnect power to
the motor and verify that the voltage is zero before performing any work on
the motor.