Unidrive M300 Quick Start Guide
21
Issue Number: 4
•
A shielded control cable, with shield clamped to the grounded metal panel
Full instructions are given in the
Drive User Guide.
A full range of external EMC filters are also available for use with
Unidrive M300
.
4.6 SAFE TORQUE OFF (STO)
The SAFE TORQUE OFF function provides a means for preventing the drive from generating torque
in the motor with a very high level of integrity. It is suitable for incorporation into a safety system for a
machine. It is also suitable for use as a conventional drive enable input.
The safety function is active when either one or both STO inputs are in the logic-low state as
specified in the control terminal specification. The function is defined according to EN 61800-5-2 and
IEC 61800-5-2 as follows. (In these standards a drive offering safety-related functions is referred to
as a PDS(SR)):
'
Power, that can cause rotation (or motion in the case of a linear motor), is not applied to the motor.
The PDS(SR) will not provide energy to the motor which can generate torque (or force in the case of
a linear motor)
'.
This safety function corresponds to an uncontrolled stop in accordance with stop category 0 of IEC
60204-1. The SAFE TORQUE OFF function makes use of the special property of an inverter drive
with an induction motor, which is that torque cannot be generated without the continuous correct
active behavior of the inverter circuit. All credible faults in the inverter power circuit cause a loss of
torque generation.
The SAFE TORQUE OFF function is fail-safe, so when the SAFE TORQUE OFF input is
disconnected the drive will not operate the motor, even if a combination of components within the
drive has failed. Most component failures are revealed by the drive failing to operate. SAFE
TORQUE OFF is also independent of the drive firmware.
For more information regarding the SAFE TORQUE OFF input, please see the
Drive User Guide.
The design of safety-related control systems must only be done by personnel with the
required training and experience. The SAFE TORQUE OFF function will only ensure the
safety of a machine if it is correctly incorporated into a complete safety system. The
system must be subject to a risk assessment to confirm that the residual risk of an unsafe
event is at an acceptable level for the application
SAFE TORQUE OFF does not provide electrical isolation. The supply to the drive must be
disconnected by an approved isolation device before gaining access to power
connections.
It is essential to observe the maximum permitted voltage of 5 V for a safe low (disabled)
state of SAFE TORQUE OFF. The connections to the drive must be arranged so that
voltage drops in the 0 V wiring cannot exceed this value under any loading condition. It is
strongly recommended that the SAFE TORQUE OFF circuits be provided with a dedicated
0 V conductors which should be connected to terminals 32 and 33 at the drive.
WARNING
WARNING
WARNING
Unidrive M300 Quick Start Guide English Iss4.book Page 21 Wednesday, July 16, 2014 8:38 AM
Summary of Contents for unidrive m300
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