Automated independent backup system
This automated independent backup standalone safety instrumented system backs up current process control trip logic and meets the requirements of IEC 61511. The system includes an IEC 61508 logic solver that is functionally independent from the process control system, supplements existing logic and meets all appropriate safety standards.
DIAMOND-SIS automated independent backup (AIB) is alow-cost, standalone safety instrumented system (SIS) that backs up currentprocess control trip logic and meets the requirements of IEC 61511. The systemincludes an IEC 61508 logic solver that is functionally independent from theprocess control system, supplements existing logic and meets all appropriatesafety standards.
DIAMOND-SIS AIB provides high integrity and process
reliability. It is available in single, dual and triplicated channel
configurations with online diagnostics, testing and maintenance capabilities.
The single and dual channel systems are acceptable for SIL 2, while the
triplicated channel systemis certified by Factory Mutual to SIL 3. This means
that DIAMOND-SIS can meet the fault tolerance and PFavg requirements of any
With its 5 A output rating, the system can de-energize
multiple final elements including motor control circuits and/or solenoid
operated valves. Local or remote manual reset ensures controlled process
restart after shutdown.
DIAMOND-SIS AIB is particularly useful with legacy control
systems that do not meet current SIS standards. Typically, during the early
days of digital control, users implemented safety logic within their process
control systems. Today, they do not want to impose SIS requirements or
management restrictions within the existing systems. Instead, they need an
independent backup safety logic system that connects easily to existing plant
equipment, meets all safety standards and requirements, and requires no
reprogramming of process logic. DIAMOND-SIS AIB fulfills all of those
A single channel DIAMOND-SIS AIB system includes a
pre-mounted and wired DIN-rail signal isolator, a Model 340 logic solver, a
fuse block and five terminals ready to accept existing wiring. All components
are rated for -30 C to 75 C and Class I Div II operation, and meet the
mechanical integrity requirements of IEC 61511.
The system can typically be mounted in an existing DCS
marshalling cabinet, and the user wires the logic solver contacts in series
with the DCS contacts. The logic solver then independently backs up the trip
functionality of the DCS.
Each DIAMOND-SIS logic solver module can accept virtually
any analog input. Its two field adjustable trip points allow the process to be
shut down on high and/or low process variables, or to detect an out of range
signal fault. The number of inputs and the voting architecture - such as 1oo1,
1oo2,2oo2 or 2oo3 - can be adjusted to meet performance requirements. The
process shutdown signal from the logic solver can be sent to both the DCS, and
directly to a shutdown device such as a relay or solenoid.
The installation does not require any reprogramming of the
existing DCS. In addition, the installation cost of a DIAMOND-SIS AIB is 80%
less than that of an equivalent Safety PLC with the same number of loops.
Maintenance costs are also greatly reduced as it's not necessary to purchase,
implementand renew programming software. The Safety Requirements Specification,
including Safety Integrity Level (SIL) verification documentation, can be