Safe Torque Off 6-18
AC30V series Variable Speed Drive
Safety Warnings and Limitations
• Only competent personnel are permitted to install the STO function and commission it. They must disseminate and make available all
appropriate instructions and documentation to all personnel who may come into contact with or operate the STO and provide suitable
training on the AC30V to ensure it is operated in the correct manner and to avoid damage, injury or loss of life.
• The AC30V STO function is a factory-fitted and factory-tested feature. Repairs to AC30V STO featured-product are to be carried out
only by Parker authorized repair centres. Any unauthorised attempt to repair or disassemble the product will render any warranty null
and void, and STO integrity could be impaired. PARKER WILL NOT ACCEPT ANY LIABILITY FOR FAILURE TO OBEY THESE
INSTRUCTIONS OR FOR ANY CONSEQUENTIAL INJURY, DEATH, LOSS OR DAMAGE.
• It is important that the AC30V product environment including all aspects of its CE conformance and IP etc., specified elsewhere in this
manual, is maintained to ensure the safety integrity of the STO function.
• Should synchronous motors be operated in the field weakening range, operation of the STO function may lead to overspeed and
destructive overvoltages as well as explosions in the drive. Therefore, the STO function must NEVER be used with synchronous drives
in the field-weakening range. The user must ensure this condition is prevented.
• When using synchronous permanent magnet motors, shaft movement over a small angle is possible if two faults occur simultaneously
in the power section of the drive. This depends on the number of motor poles. The maximum angle is:
Rotary motors: 360° / number of poles.
Linear motors: 180° electrically.
It is the user’s responsibility to assess, validate and safeguard as necessary against this potential hazard.
• If external forces can act on the motor and/or load to cause it to move, additional measures must be taken by the user to restrain it, for
example a mechanical brake. Examples of external forces are suspended loads (effect of gravity), and other web-tensioning devices.
• The AC30V STO feature does not provide or guarantee any galvanic isolation in accordance with EN 60204-1:2006 A1:2009 Section
5.5. This means that the entire system must be isolated from the mains power supply with a suitable electrical isolation device before
any drive or motor maintenance or replacement procedures are attempted. Note that even after the power has been isolated,
dangerous electrical voltages may still be present in the AC30V drive. Safe discharge times and details are specified in Chapter 1
Safety of this manual.
• The STO function must not be used for electrical isolation of the AC30V drive and power. Whenever any personnel require to work on
the drive, associated motor or other power items, they must always use recognised and suitable electrical isolation devices.
• Terminal X10/02 or X10/04 must be connected to earth at one common point in the drive system. For multi-drive systems this can be a
shared earth point.
• The STO user output, serial communications or GKP messages relating to accessing or viewing any safety monitoring statuses are for
information only and should not be relied on. They are not part of the drive module safety system and its associated PL/SIL declared
ratings. Any customer use of these must be appropriately risk assessed in accordance with the relevant standards or regulations.
• The STO safety function must be tested regularly. The frequency should be determined by the machinery builder. An initial minimum
frequency of once per week is suggested. Refer to page 6-27 and following pages.
• When using an external safety control unit with adjustable time delay, for example when implementing an SS1 function, the time delay
must be protected to prevent unauthorized adjustment. The adjustable time delay on the safety control unit must be set to a value
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