Safety instruction and information for use
Motivations for integrated safety function
As a result of automation, demand for increased production and reduced operator physical effort,
control systems of machinery and plant items play an increasing role in the achievement of overall
safety. These control systems increasingly employ complex electrical/electronic/programmable
electronic devices and systems.
Prominent amongst these devices and systems are adjustable speed electrical power drive
systems (PDS) that are suitable for use in safety-related applications (PDS-SR).
Electronic protection are integrated into the drive in order to perform safety function to minimise
or excrete hazards due to functional errors using machinery.
Integrated safety function replaces external safety components. STO integrated function can be
used as an alternative to motor contactors in order to control unexpected motor re-start, whether
risk assessment permit it. According to previous paragraph safety integrated function applicability
depends application and applicable standards.
The whole safety related part of the control system, using the drive integrated safety function, has
to work properly in normal and misuse state. It must be trouble-free and reach a safe state.
In order to check for those requirements, the whole safety related control system must be
analysed by means of FMECA, fault tree, etc.
Safe torque off function description
Safety function, "Safe Torque off" (STO) is a safety function used to break off power and current
output onto the motor in order to prevent unexpected movements and voltages. ADL300 drive
family supports "Safe Torque Off" as an integrated feature.
This function does not disconnect the machine from electrical power supply. It shall be stressed
that safety equipped drive units are just one component in a safety control system whereas STO is
system level function. Parts and components of the system must be chosen, applied and
integrated appropriately to achieve the desired level of operational safety.
ADL300 is a specialized drive family intended for the Lift Market. Given this ADL300 STO
function will be primarily exploited to attain safety features permitted and described by C class
- Car safe stop suing one contactor design
normative EN81-1, EN81-20, EN81-50. Specifically the safety integrated function allows getting rid
- Car safe stop using contactor-less design
of one or two contactors and implementation of:
STO is integrated in the drive unit family ADL300, whereas safety capability could also be
implemented externally. When Safety is used power disconnection between the drive controller
and the motor, required to achieve a "safe stand-still", is obtained without the use of external
contactors and or relays.
Function should not be mistaken with "Mains supply disconnection (isolating)and switch-off ",
section 5.3 isolation from power supply system, requested by EN 60204-1.