What is 2oo3 voting logic?
Two out of three logic is called the triple module redundancy or triple mode redundancy, in which three independent inputs are connected to a system and the output, comes out based on the maximum number of voting.
What is difference between 1oo2 and 1oo2D?
The primary difference in the 2oo2D versus the 1oo2D occurs when there is a dangerous undetected failure in one unit. Because of the added control lines and readback diagnostics, the operating unit can de-energize the failed unit. The 1oo2D architecture provides 1oo2 type functionality in this situation.
What is voting logic in PLC?
Voting logic is applied to minimize the occurrence of complete loss of production caused by single transmitter fault or spurious trip shutdown. The voting configuration can be 2oo3 or 1oo2D based on SIL assessment and verification.
What is sis control system?
A safety instrumented system (SIS) consists of an engineered set of hardware and software controls which are especially used on critical process systems.
What is hardware fault tolerance?
‘Hardware fault tolerance is the ability of a component or subsystem to continue to be able to undertake the required safety instrumented function in the presence of one or more dangerous faults in hardware.
What is 1oo2D voting?
This designation for 1oo2D stands for a 1 out of 2 redundancy voting scheme with Diagnostics, e.g. by design requires that only one out of two devices or channels in a device to work for the redundancy scheme/voting to properly perform its safety functionality.
What is 1oo2 architecture?
In contrast, full 1oo2 architecture consists of two channels throughout the system (sensors, inputs, logic solver, outputs, field devices), where each of the redundant logic solvers can execute the safety function individually.
What is 2oo2 architecture?
Another dual controller configuration was developed for the situation in which it is undesirable to fail with outputs de-energized. This system is used in energize-to-trip protection systems. The outputs of two controllers are wired in parallel (Figure F-10).
What is the difference between SIS and ESD?
Fusible elements of the fire loop may be integrated with the ESD control loop. Thus ESD is part of SIS for safety purpose to protect either plant or people and ESD will active when there is someone activated.
What is SIS and BPCS?
Most industrial processes incorporate Safety Instrumented Systems (SIS) and Basic Process Control Systems (BPCS) in their operations.
What is HFT in SIL?
Fault Tolerance for Safety Levels of Hardware Fault Tolerance (HFT) are specified in functional safety standards IEC 61508 and IEC 61511, primarily for safety reasons. Very generally speaking, the higher the safety integrity Level (SIL) required, the more hardware fault tolerance is expected in the design.
What is redundancy and fault tolerance?
The term “redundancy,” as used in this guide, is the ability to configure one or more backup components (or cards) to take over for a component that fails. Redundancy provides system-wide fault tolerance, helping to ensure that the CSP continues to process calls despite a hardware or software fault.
What is 2oo2D?
The 2oo2D is a four channel architecture that consists of two 1oo1D controllers arranged in a 2oo2 style (Figure F-26). Since the 1oo1D protects against dangerous failures when diagnostics detect the failure, two units can be wired in parallel to protect against shutdowns.
What is 1oo1D?
1oo1D One(1) out of One(1) safety channel architecture with Diagnostics. 1oo2 One(1) out of Two(2) safety channel architecture.
What is ESD and PSD?
PSD and ESD can be considered as effects, which are triggered by certain causes, the PSD and ESD are levels of shutdown which discriminate between the seriousness of the causes leading to the appropriate effects.
What is ESD and F&G?
ESD systems are preventative layers of protection, meaning that they act to prevent a hazardous event like a chemical release, fire, or explosion from occurring. A FGS is a mitigating layer of protection, because the purpose is to reduce the consequence severity of such an event when it occurs.
What does BPCS mean?
Basic Process Control System (BPCS) is a system which handles process control and monitoring for a facility or piece of equipment. It takes inputs from sensors and process instrumentations to provide an output based on an approved design control strategy.
What is SFF in SIL?
The term Safe Failure Fraction (SFF) is coined, in IEC 61508. It is defined as the sum of the potentially dangerous failures revealed by auto-test together with those which result in a safe state, as a fraction of the TOTAL number of failures.
What does a HFT of 1 mean?
hardware fault tolerance
Fault Tolerance for Safety All such “single channel” systems, by definition, have no ability to tolerate faults. Systems or functions with ONE LEVEL of hardware fault tolerance (HFT = 1) are designed to tolerate a single dangerous failure.
What is the difference between HA and redundancy?
High Availability vs. The primary goal of high availability is to ensure system uptime even in the event of a failure. Redundancy, on the other hand, is the use of additional software or hardware to be used as backup in the event that the main software or hardware fails.
What is ESD in DCS?
ESD system ensures priority control of process equipment which is required for switching the process in safe mode. The system performs the following functions: Collection and processing of ESD-connected information about process parameters and equipment state.
What is PSD in safety?
Process shutdown (PSD) system is a part of plant (facility) safeguarding system with a purpose to minimize the frequency and consequences of excursions outside the facility operating envelope.
What is ESD in oil and gas?
An emergency shutdown system or ESD is a system that is used in hazardous areas to prevent situations that could have catastrophic effects economically, environmentally, or operationally.
What is BPCS and SIS?
Basic Process Control Systems and Safety Instrumented System Devices. The design of a secure and safe ICS system depends on the ability to assess the security of each component, such as Basic Process Control Systems (BPCS) and safety instrumented system (SIS) devices.
When we must use 1oo1 1oo2 2oo2 or 2oo3 voting logic architecture?
In general when we must use 1oo1, 1oo2, 2oo2, or 2oo3 voting logic architecture? As mentioned above, there are two purposes why certain voting logic architecture were chosen, first is to reach certain SIL and secondly to reach certain cost reduction due to spurious platform shutdown.
What is a 2oo3 architecture?
An architecture designed to tolerate both “safe” and “dangerous” failures is the 2oo3 (two units out of three are required for the system to operate). This architecture provides both safety and high availability with three controller units.
What voting logic architecture should be used for SIL 3?
If 1oo1 sensor, 1oo1 logic solver, and 1oo1 shutdown valve can fulfill the SIL 3 requirement, then this architecture is chosen. If not, then any other voting logic architecture is investigated.
What happens if one unit fails in a 2oo3 architecture?
If one unit fails short circuit the system effectively degrades to a 2oo2 configuration. In both cases, the system remains in successful operation. The 2oo3 architecture will fail dangerously only if two units fail dangerously (Figure F-22).