Electricity + Control May 2015

13 / 48

ROUND UP ANALYTICAL INSTRUMENTATION
High availability and functional safety up to SIL3
The requirements on operational and safety-related circuits in plants
are continuously growing which also affect the technical require-
ments on components. Often, functional safety can only be increased
with much effort and at the expense of availability.
Proving that high safety standards and high availability can go
hand in hand, Knick has introduced ProLine P 22400 passive standard
signal isolators certified for applications with a SIL3 safety integrity
level according to EN 61508.The passive isolator’s safety functional-
ity is the highly precise, linear transmission of 4...20 mA signals with
a low transmission error of 0,08 % full scale. A high level of func-
tional safety can be achieved even in single-channel structure and
without diagnostics. For instance, sensors and actuators in safety
circuits can be connected directly, requiring no elaborate evaluation
equipment for redundant structures. The isolator’s robust design
ensures excellent availability with a mean time between failures
of 965 years. Thanks to loop-powered operation, it contains fewer
parts than devices with an auxiliary power unit and the total failure
rate is decreased. Furthermore, it is mechanically stable, approved
for marine applications, resistant against electromagnetic interfer-
ences, and boasts protection against electric shocks up to 600Vac/dc
through reinforced insulation.The test voltage during routine testing
is 5,4 kVac. ProLine P 22400 is suitable for ambient temperatures
between -40 and 85 °C. Knick provides a five-year warranty for all
ProLine devices.
Mecosa is the sole agent for Knick ElektronischeMessgeräte in
Southern Africa.
. 011 257 6100 or email