Motors and Drives
Cost and time savings with drive-based functional safety
Significant advances in drive technology now allow for safety functions to be built directly into the drive which controls motor and machinery movements. This article examines how safety designers and machine builders can simplify their work while providing higher overall safety and protection levels.
M
achine safety strategies aimed at protecting people, property and ecosystems can benefit from recent innovations in drive technology. Drive technology today allows safety
functions to be built directly into the drive in an effortless manner. This gives big benefits to machine builders, designers, engineers and users who want to meet proper safety requirements with less hassle while saving time and money.
Integrated drive-based functional safety
Implementing a machine safety system from start to finish can be seen as a daunting and complicated undertaking. Thanks to new safety technology in drives and standardisation that unifies requirements and terminology used in the market, this process has been made easier. New electronic safety solutions integrated into the drive are perfectly capable of replacing the use of traditional safety systems that involve hard-wired logic add-ons like relays and contactors. The safe torque off (STO) safety function comes integrated in many ABB drives. Using an optional safety functions module, additional safety functions can be integrated into the new all-compatible ACS880 industrial drives. A few of the most
Fig. 1. The safety functions module, FSO-11.
important benefits that can be obtained with integrated safety in drives include reduced design time and effort and easy commissioning of one or several built- in pre-programmed safety functions. Other
advantages are reduced numbers of devices, amount of cabling, and cost savings, as well as no wearing parts compared to traditional electromechanical safety devices.
Functional safety design tool simplifies designer’s life
One of the key initial tasks of a safety designer’s job is to conduct a risk analysis aimed at defining where safety is needed on the machine and then deciding which safety levels and functions are required for making the machine safe. To make this work easier, ABB’s new Functional safety design tool (FSDT-01) helps machine builders, OEMs and system integrators to calculate, verify and document the required, designed and achieved safety integrity level (SIL) or performance level (PL) using a very logical stepwise procedure, in accordance with machinery standards EN IEC 62061 and EN ISO 13849-1. The Functional safety design tool cuts the designer’s
workload by simplifying and speeding up the design process, while simultaneously ensuring the safety design calculations are met according to standards. Additionally, the design tool is compatible with numerous safety libraries including ABB safety devices as well as other manufacturers, thus making calculations and device selection much faster and easier.
Safe torque off (STO)
Once the machine design is approved, drive-based functional safety is ready for implementation. Safe torque off (STO), which is the safety function that brings drives safely to a no-torque state (eg, emergency stop) and/or prevents an accidental unexpected start- up, is the compulsory foundation of integrated drive- based functional safety. STO is therefore built into the drive as an electronic safety function to be used as an alternative to traditional electromechanical methods such as contactors. Underlining ABB’s commitment to drive-based
functional safety, many of its drives have STO built- in as a standard feature. The all-compatible ACS880 drive series is the best-equipped, most-modern example of integrated safety in drives, with STO as a standard
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