Industrial safety – the view from a variable speed drives manufacturer



By Tushar Narwade, Specialist- Servo Motion, Inovance Technology India


Industrial safety is a fundamental requirement, and it is the responsibility of hardware
manufacturers to offer products with market-leading safety features, so that factory managers can
provide a safe working environment for employees. In India, as in many other countries, employee
safety is increasingly moving up the agenda – and rightly so. Functional safety is about reducing risk
of accidents to an acceptable level, and it is prescribed by a series of safety standards: IEC, ISO and
EN. Safe torque off (STO) is the most common and basic drive-integrated safety function.
The ability of STO to perform the safety function is measured by the Safety Integrity Level (SIL). SIL 3
is the highest level applicable for industrial equipment, which results in a very low probability of
failure. STO guarantees safe machine stop without using additional contactors. Replacing magnetic
contactors reduces both cabinet size and installation costs; and it is also safer because it prevents
the possibility of arcing events. Additionally, STO offers greater reliability than with using a contactor
because it has no moving parts. STO works by blocking the pulses of the drive, ensuring that no
torque-generating energy can continue to travel to the motor, and preventing unintentional start
Here at Inovance – a $1.7bn+ global industrial automation company with pan-Indian sales and
support – we offer the full range of industrial automation products from variable speed drives and
servos, to CNCs, PLCs and HMIs. Our SV660 single axis EtherCAT servo – which is equipped with STO
functionality – is one of our leading servo products. The drive offers high dynamic performance with
a compact footprint (30% smaller than the equivalent previous generation product), is user friendly,
and is extremely easy to set up and tune. An ultra-fast 4.5 kHz current loop bandwidth allows the
motor to follow the motion profile with minimal error. The drive achieves a radically improved
system performance with a shorter settling time and higher throughput. An isolated cooling channel
prevents dust contamination of internal electrical components, and conformally coated PCBs are
resistant to 3S2 and 3C2 environments providing further protection.
The drive has been designed from the ground up with safety in mind. That’s why it features both STO
SIL 3 and also short output winding – which ensures safe breaking even in the case of a failure in the
motor holding brake. While, in the Indian market, STO is often an expensive addition to a drive, this
is not the case with the SV660N servo drive. STO comes fitted to SV660N as standard, and the drive
is highly competitive in price with similar non-STO products in the Indian market. All our latest
products have STO capability, such as the MD810 AC MultiDrive and the IS810 MultiAxes EtherCAT
To continue the conversation about industrial safety, get in touch with me directly: tushar.n@inova-

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