By contrast, the U-ONE-SAFETY makes it easy to implement movement and position dependent safety functions. Depending on requirements U-ONE-SAFETY monitors the safety functions SLS (Safely-Limited Speed), SSM (Safe Speed Monitor), SDI (Safe Direction), SLP (Safely-Limited Position) and SCA (Safe Cams) — and is
configured according to customer specifications. Monitoring the
speed and position of the deployed traversing and hoisting
equipment are typical tasks in the bulk goods sector. When
hoisting gear is lowered, SLP monitoring, for example, can ensure
defined limit positions are reliably monitored. When configuring
the U-ONE-SAFETY the traversing range is initially calibrated.
Subsequently, it is possible to define several points within this
range at which reliable safety monitoring is desired. For instance,
when hoisting gear moves loads it is often permissible to travel
at greater speeds at mid height than after a defined slow-down
point is reached close to a final position switch, at which point
travel speeds must be slower.
MORE THAN JUST A NORMAL ENCODER
In particular the safe position and error switches as well as the
safe absolute encoder interfaces are new features in comparison
with the previous version of the U-ONE-SAFETY. In addition,
the system offers a reliable speed switch as well as optional
current or incremental outputs. It is possible to simply and
reliably programme the respective parameters utilizing the
configuration software included in the scope of supply —
without having to intervene in the higher-level controls. Thomas
Brandenburger, head of the project management department,
explains:“With integrated safety logic and safe switching outputs
U-ONE-SAFETY is far more than just a normal encoder. The
user is able to very easily implement speed and position
dependent safety functions without needing a lot of programming
know-how. And in the event a device needs to be replaced the
stored parameters can easily be transferred to the new device —
it can’t get more straightforward than that.”
CERTIFICATION FACILITATES SIMPLIFIED SAFETY REVIEW
With integrated dual channel architecture and internal cross-
checking the U-ONE-SAFETY is ideally suited for applications up
to safety category 3 and Performance Level (PL) d to DIN EN
ISO 13849 as well as Safety Integrity Level (SIL) 2 to DIN EN
61508. The advantage of dual channel architecture: the safety function is always retained even when an error occurs. Two
separate sensors generate a signal independent of one another.
Two logic units cross-check if the values are identical. Finally, the
signals are fed to a switching output (speed and position switches
are possible), which also boasts dual channel architecture. “This
integrated, system-wide dual channel architecture is the basis for
the classification in safety category 3. That means it is possible to
deploy the U-ONE-SAFETY in a much wider spectrum of
applications”, says Brandenburger. Certification means it is
possible to classify the device as a safety component during the
safety review required by the standard, something that
significantly reduces the burden of assessment on the part of the
customer.
It is possible to combine the different functions, output signals
and interfaces within the scope of a modular concept to create
the right solution for the respective application. Two different
versions of the system are available: the U-ONE-SAFETY-
Compact that sees modules attached to the basic unit within a
compact casing; then there is the U-ONE-SAFETY-LWL that
features a basic unit in a robust casing, which is connected to the
corresponding modules in the switchboard enclosure via fibre
optic cabling.
RUGGED AND RELIABLE: IDEAL FOR NEW INSTALLATIONS AND
UPGRADE PROJECTS
“With U-ONE-SAFETY the customer receives all of the
functions and interfaces he requires in a single compact device”,
explains Brandenburger. U-ONE-SAFETY is suitable for both new
installations and upgrade projects. This system means there is no
longer any need for mechanical cam switches, mechanical cam
controllers, intermediate or limit switches. Characteristics such
as the rugged construction, the high degree of protection, even
when the terminal box is open (thanks to the fully encapsulated
base), and robust O-ring-seals in the terminal box cover ensure
the U-ONE-SAFETY is the right solution for use in extreme
environments – in particular in steel and rolling mills, in mining, in
crane technology and in the bulk goods sector. Moreover, all of
the devices offer high connection flexibility with safe cable
entries – on both sides.