Pepperl+Fuchs SIL KCD2-STC-1.SP User manual

ISO9001
2
Functional Safety
SMART Transmitter Power Supply
KCD2-STC-(Ex)1(.SP)(-Y1),
HiC2025(Y1)
PROCESS AUTOMATION
MANUAL

With regard to the supply of products, the current issue of the following document is applicable: The General Terms of
Delivery for Products and Services of the Electrical Industry, published by the Central Association of the Electrical
Industry (Zentralverband Elektrotechnik und Elektroindustrie (ZVEI) e.V.) in its most recent version as well as the
supplementary clause: "Expanded reservation of proprietorship"
Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Content
2018-08
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1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Content of this Document. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Safety Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3 Symbols Used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Product Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3 Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4 Standards and Directives for Functional Safety . . . . . . . . . . . . . . . . . . 9
3 Planning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1 System Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
3.2 Assumptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
3.3 Safety Function and Safe State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4 Characteristic Safety Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.5 Useful Lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4 Mounting and Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
4.1 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.1 Proof Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6 Maintenance and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7 List of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Introduction
1Introduction
1.1 Content of this Document
This document contains information for usage of the device in functional safety-related
applications. You need this information to use your product throughout the applicable stages of
the product life cycle. These can include the following:
• Product identification
• Delivery, transport, and storage
• Mounting and installation
• Commissioning and operation
• Maintenance and repair
• Troubleshooting
• Dismounting
• Disposal
The documentation consists of the following parts:
• Present document
• Instruction manual
•Manual
•Datasheet
Additionally, the following parts may belong to the documentation, if applicable:
• EU-type examination certificate
• EU declaration of conformity
• Attestation of conformity
• Certificates
• Control drawings
• FMEDA report
• Assessment report
• Additional documents
For more information about Pepperl+Fuchs products with functional safety, see www.pepperl-
fuchs.com/sil.
Note!
This document does not substitute the instruction manual.
Note!
For full information on the product, refer to the instruction manual and further documentation
on the Internet at www.pepperl-fuchs.com.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Introduction
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1.2 Safety Information
Target Group, Personnel
Responsibility for planning, assembly, commissioning, operation, maintenance, and
dismounting lies with the plant operator.
Only appropriately trained and qualified personnel may carry out mounting, installation,
commissioning, operation, maintenance, and dismounting of the product. The personnel must
have read and understood the instruction manual and the further documentation.
Intended Use
The device is only approved for appropriate and intended use. Ignoring these instructions will
void any warranty and absolve the manufacturer from any liability.
The device is developed, manufactured and tested according to the relevant safety standards.
Use the device only
• for the application described
• with specified environmental conditions
• with devices that are suitable for this safety application
Improper Use
Protection of the personnel and the plant is not ensured if the device is not used according to
its intended use.

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Introduction
1.3 Symbols Used
This document contains symbols for the identification of warning messages and of informative
messages.
Warning Messages
You will find warning messages, whenever dangers may arise from your actions. It is
mandatory that you observe these warning messages for your personal safety and in order to
avoid property damage.
Depending on the risk level, the warning messages are displayed in descending order as
follows:
Informative Symbols
Action
This symbol indicates a paragraph with instructions. You are prompted to perform an action or
a sequence of actions.
Danger!
This symbol indicates an imminent danger.
Non-observance will result in personal injury or death.
Warning!
This symbol indicates a possible fault or danger.
Non-observance may cause personal injury or serious property damage.
Caution!
This symbol indicates a possible fault.
Non-observance could interrupt the device and any connected systems and plants, or result
in their complete failure.
Note!
This symbol brings important information to your attention.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Product Description
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2 Product Description
2.1 Function
KCD2-STC-1(.SP)
This signal conditioner provides the galvanic isolation between field circuits and control
circuits.
The device supplies 2-wire transmitters in the field, and can also be used with current sources.
The device transfers the analog input signal to the control side as an isolated current value.
Bi-directional communication is supported for SMART transmitters that use current modulation
to transmit data and voltage modulation to receive data.
If the HART communication resistance in the loop is too low, the internal resistance
can be used.
Test sockets for the connection of HART communicators are integrated into the terminals
of the device.
The output is selected as a current source, current sink, or voltage source via DIP switches.
The device is mounted on a 35 mm DIN mounting rail according to EN 60715.
SP version
The devices are available with screw terminals or spring terminals. The type code
of the versions of the devices with spring terminals has the extension ".SP".
KCD2-STC-Ex1(.SP)
This isolated barrier is used for intrinsic safety applications.
The device supplies 2-wire transmitters in the hazardous area, and can also be used
with current sources.
The device transfers the analog input signal to the non-hazardous area as an isolated current
value.
Bi-directional communication is supported for SMART transmitters that use current modulation
to transmit data and voltage modulation to receive data.
If the HART communication resistance in the loop is too low, the internal resistance
can be used.
Test sockets for the connection of HART communicators are integrated into the terminals
of the device.
The output is selected as a current source, current sink, or voltage source via DIP switches.
The device is mounted on a 35 mm DIN mounting rail according to EN 60715.
SP version
The devices are available with screw terminals or spring terminals. The type code
of the versions of the devices with spring terminals has the extension ".SP".

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Product Description
KCD2-STC-Ex1-Y1
This isolated barrier is used for intrinsic safety applications.
The device supplies 2-wire transmitters in the hazardous area.
The device transfers the analog input signal to the non-hazardous area as an isolated current
value.
Bi-directional communication is supported for SMART transmitters that use current modulation
to transmit data and voltage modulation to receive data.
If the HART communication resistance in the loop is too low, the internal resistance
can be used.
Test sockets for the connection of HART communicators are integrated into the terminals
of the device.
The output is selected as a current source, current sink, or voltage source via DIP switches.
The device is mounted on a 35 mm DIN mounting rail according to EN 60715.
HiC2025
This isolated barrier is used for intrinsic safety applications.
The device supplies 2-wire transmitters in the hazardous area, and can also be used
with current sources.
The device transfers the analog input signal to the non-hazardous area as an isolated
current value.
Bi-directional communication is supported for SMART transmitters that use current modulation
to transmit data and voltage modulation to receive data.
The output is selected as a current source, current sink, or voltage source via DIP switches.
This device mounts on a HiC termination board.
HiC2025Y1
This isolated barrier is used for intrinsic safety applications.
The device supplies 2-wire transmitters in the hazardous area.
The device transfers the analog input signal to the non-hazardous area as an isolated
current value.
Bi-directional communication is supported for SMART transmitters that use current modulation
to transmit data and voltage modulation to receive data.
The output is selected as a current source, current sink, or voltage source via DIP switches.
This device mounts on a HiC termination board.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Product Description
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2.2 Interfaces
The device has the following interfaces.
• Safety relevant interfaces: input I, output I
• Non-safety relevant interfaces: none
The HART communication is not relevant for functional safety.
2.3 Marking
2.4 Standards and Directives for Functional Safety
Device-specific standards and directives
System-specific standards and directives
Note!
For corresponding connections see datasheet.
Pepperl+Fuchs GmbH
Lilienthalstraße 200, 68307 Mannheim, Germany
Internet: www.pepperl-fuchs.com
KCD2-STC-1(.SP) Up to SIL 2
KCD2-STC-Ex1(.SP)(-Y1)
HiC2025(Y1)
Functional safety IEC/EN 61508, part 1 –2, edition 2000:
Functional safety of electrical/electronic/programmable electronic
safety-related systems (manufacturer)
Functional safety IEC/EN 61511, part 1, edition 2003:
Functional safety –Safety instrumented systems for the process
industry sector (user)

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Planning
3 Planning
3.1 System Structure
3.1.1 Low Demand Mode of Operation
If there are two control loops, one for the standard operation and another one for the functional
safety, then usually the demand rate for the safety loop is assumed to be less than
once per year.
The relevant safety parameters to be verified are:
•thePFD
avg value (average Probability of dangerous Failure on Demand) and the T1
value (proof test interval that has a direct impact on the PFDavg value)
• the SFF value (Safe Failure Fraction)
• the HFT architecture (Hardware Fault Tolerance)
3.1.2 High Demand or Continuous Mode of Operation
If there is only one safety loop, which combines the standard operation and safety-related
operation, then usually the demand rate for this safety loop is assumed to be higher than once
per year.
The relevant safety parameters to be verified are:
•thePFHvalue(Probability of dangerous Failure per Hour)
• Fault reaction time of the safety system
• the SFF value (Safe Failure Fraction)
• the HFT architecture (Hardware Fault Tolerance)
3.1.3 Safe Failure Fraction
The safe failure fraction describes the ratio of all safe failures and dangerous detected failures
to the total failure rate.
SFF = (s+ dd) / (s+ dd + du)
A safe failure fraction as defined in IEC/EN 61508 is only relevant for elements or (sub)systems
in a complete safety loop. The device under consideration is always part of a safety loop
but is not regarded as a complete element or subsystem.
For calculating the SIL of a safety loop it is necessary to evaluate the safe failure fraction
of elements, subsystems and the complete system, but not of a single device.
Nevertheless the SFF of the device is given in this document for reference.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Planning
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3.2 Assumptions
The following assumptions have been made during the FMEDA:
• Failure rate based on the Siemens standard SN29500.
• Failure rates are constant, wear is not considered.
• External power supply failure rates are not included.
• The devices are not protected against power supply failures. It is within the responsibility
of the user to ensure that low supply voltages are detected and adequate reaction on
this fault is implemented.
• The safety-related device is considered to be of type Adevice with a hardware fault
tolerance of 0.
• The device will be used under average industrial ambient conditions comparable to
the classification "stationary mounted" according to MIL-HDBK-217F.
Alternatively, operating stress conditions typical of an industrial field environment similar
to IEC/EN 60654-1 Class C with an average temperature over a long period of time
of 40 ºC may be assumed. For a higher average temperature of 60 ºC, the failure rates
must be multiplied by a factor of 2.5 based on experience. A similar factor must be used
if frequent temperature fluctuations are expected.
• The HART function is only used for configuration, calibration and diagnostics, not during
operation.
• The indication of a dangerous failure (via fault bus) is detected within 1 hour by the
programmable logic controller (PLC).
SIL 2 Application
• The device shall claim less than 10 % of the total failure budget for a SIL 2 safety loop.
• For a SIL 2 application operating in low demand mode the total PFDavg value
of the SIF (Safety Instrumented Function) should be smaller than 10-2, hence the
maximum allowable PFDavg value would then be 10-3.
• For a SIL 2 application operating in high demand mode the total PFH value of the SIF
should be smaller than 10-6 per hour, hence the maximum allowable PFH value would then
be 10-7 per hour.
• Since the safety loop has a hardware fault tolerance of 0and it is a type Adevice,
the SFF must be > 60 % according to table 2 of IEC/EN 61508-2 for a SIL 2 (sub) system.

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Planning
3.3 Safety Function and Safe State
Safety Function
The device transfers analog signals from the input to the output with a tolerance of 2 % related
to the full signal range.
Use the following DIP switch settings for safety-relevant applications:
DIP Switch Settings KCD2-STC-(Ex)1(.SP)(-Y1)
DIP Switch Settings HiC2025(Y1)
Safe State
In the safe state, the following values must be reached at the output:
• < 3.6 mA or > 21.5 mA,
• < 0.9 V or > 5.375 V,
Reaction Time
The reaction time for all safety functions is < 20 ms.
Function S1 S2 S3 S4
Current source 4 mA to 20 mA II II III
Voltage source 1 V to 5 V II II I I
Current sink 4 mA to 20 mA II III II
Table 3.1
Function S1 S2 S3 S4
Current source 4 mA to 20 mA OFF OFF ON OFF
Voltage source 1 V to 5 V OFF OFF ON ON
Current sink 4 mA to 20 mA OFF ON OFF OFF
Table 3.2
Note!
See corresponding datasheets for further information.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Planning
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3.4 Characteristic Safety Values
The characteristic safety values like PFD, SFF, HFT and T1are taken from
the SIL report/FMEDA report. Observe that PFD and T1are related to each other.
The function of the devices has to be checked within the proof test interval (T1).
Parameters Characteristic values
Assessment type Full assessment
Device type A
Mode of operation Low demand mode or high demand mode
HFT 0
SIL 2
Safety function Signal transfer
s122 FIT
dd 172 FIT
du 45 FIT
no effect 122 FIT
total (safety function) 338 FIT
not part 72 FIT
SFF 86.8 %
MTBF 1
1acc. to SN29500. This value includes failures which are not part of the safety function/MTTR = 8 h.
278 years
PFH 4.45 x 10-8 1/h
PFDavg for Tproof = 1 year 1.95 x 10-4
PFDavg for Tproof = 2 years 3.90 x 10-4
PFDavg for Tproof = 5 years 9.74 x 10-4
Reaction time 2
2Time between fault detection and fault reaction
< 20 ms
Table 3.3

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Planning
3.5 Useful Lifetime
Although a constant failure rate is assumed by the probabilistic estimation this only applies
provided that the useful lifetime of components is not exceeded. Beyond this useful lifetime,
the result of the probabilistic estimation is meaningless as the probability of failure significantly
increases with time. The useful lifetime is highly dependent on the component itself and
its operating conditions –temperature in particular. For example, the electrolytic capacitors
can be very sensitive to the operating temperature.
This assumption of a constant failure rate is based on the bathtub curve, which shows
the typical behavior for electronic components.
Therefore it is obvious that failure calculation is only valid for components that have this
constant domain and that the validity of the calculation is limited to the useful lifetime of
each component.
It is assumed that early failures are detected to a huge percentage during the installation and
therefore the assumption of a constant failure rate during the useful lifetime is valid.
However, according to IEC/EN 61508-2, a useful lifetime, based on general experience,
should be assumed. Experience has shown that the useful lifetime often lies within a range
periodofabout8to12years.
As noted in DIN EN 61508-2:2011 note N3, appropriate measures taken by the manufacturer
and plant operator can extend the useful lifetime.
Our experience has shown that the useful lifetime of a Pepperl+Fuchs product can be higher
if the ambient conditions support a long life time, for example if the ambient temperature
is significantly below 60 °C.
Please note that the useful lifetime refers to the (constant) failure rate of the device.
The effective life time can be higher.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Mounting and Installation
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4 Mounting and Installation
Mounting and Installing the Device
1. Observe the safety instructions in the instruction manual.
2. Observe the information in the manual.
3. Observe the requirements for the safety loop.
4. Connect the device only to devices that are suitable for this safety application.
5. Check the safety function to ensure the expected output behavior.
4.1 Configuration
Configuring the Devices with DIP Switches on the Device Side
The device is configured via DIP switches. The DIP switches for setting the safety functions
are on the side of the device.
1. De-energize the device before configuring the device.
2. Remove the device.
3. Configure the device for the required safety function via the DIP switches, see chapter 3.3.
4. Secure the DIP switches to prevent unintentional adjustments.
5. Mount the device.
6. Connect the device again.
Configuring the Devices with DIP Switches on the Front Side
The device is configured via DIP switches. The DIP switches for setting the safety functions
are on the front of the device.
1. De-energize the device before configuring the device.
2. Open the cover.
3. Configure the device for the required safety function via the DIP switches, see chapter 3.3.
4. Close the cover.
5. Secure the DIP switches to prevent unintentional adjustments.
6. Connect the device again.
Note!
See corresponding datasheets for further information.

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Operation
5Operation
Operating the device
1. Observe the safety instructions in the instruction manual.
2. Observe the information in the manual.
3. Use the device only with devices that are suitable for this safety application.
4. Correct any occurring safe failures within 8 hours. Take measures to maintain
the safety function while the device is being repaired.
5.1 Proof Test Procedure
According to IEC/EN 61508-2 a recurring proof test shall be undertaken to reveal potential
dangerous failures that are not detected otherwise.
Check the function of the subsystem at periodic intervals depending on the applied PFDavg
in accordance with the characteristic safety values. See chapter 3.4.
It is under the responsibility of the plant operator to define the type of proof test and the interval
time period.
Equipment required:
• Digital multimeter with an accuracy better than 0.1 %
Use for the proof test of the intrinsic safety side of the device a special digital multimeter
for intrinsically safe circuits.
If intrinsically safe circuits are operated with non-intrinsically safe circuits, they must
no longer be used as intrinsically safe circuits.
• Power supply set to nominal voltage of 24 V DC
• Process calibrator with current source and current sink function with an accuracy better
than 20 µA
Danger!
Danger to life from missing safety function
If the safety loop is put out of service, the safety function is no longer guaranteed.
• Do not deactivate the device.
• Do not bypass the safety function.
• Do not repair, modify, or manipulate the device.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Operation
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Proof Test Procedure
The proof test reveals almost all possible dangerous faults (diagnostic coverage > 90 %).
1. Put out of service the entire safety loop. Protect the application by means of other measures.
2. Prepare a test set-up, see figures below.
3. Test the devices. Verify the current values as given in table below.
4. Set back the device to the original settings for the application after the test.
Figure 5.1 Proof test set-up for KCD2-STC-(Ex)1(.SP)(-Y1)
Usage in Zone 0, 1, 2/Div. 1, 2 only for KCD2-STC-Ex1(.SP)(-Y1)
For Y1 version only connect the multimeter to terminals 1 and 2.
Step No. Input Output
Input value (mA) Output value (mA) Output value for
2-wire Tx (V)
Output value for
4-wire Tx (V)
120.00 20.00 ±0.4 15.2 ±0.4 4.7 ±0.5
212.00 12.00 ±0.4 17.0 ±0.4 4.7 ±0.5
34.00 4.00 ±0.4 18.9 ±0.4 4.7 ±0.5
4 1
1The output shall detect a fail high or fail low condition.
23.00 23.00 ±0.4 14.1 ±0.4 4.7 ±0.5
5 10< 0.2 22.5 ±0.5 n. a.
612.00
Table 5.1 Steps to be performed for the proof test
KCD2-STC-Ex1(.SP)
6+
5-
3+
4-
1+
2-
Multimeter
(V)
Zone 0, 1, 2
Div. 1, 2
Zone 2
Div. 2
Multimeter
(V)
Multimeter
(V)
9+
10-
I
supply
Passive
input
Input sensor
(4-wire Tx
externally
powered)
Active
input
Input sensor
(2-wire Tx
loop powered)
24 V DC
Power
supply
Logic
solver
analog
input
Current source or
Voltage source or
Current sink
Supply
4 mA to 20 mA
4 mA to 20 mA
I
supply

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Operation
Figure 5.2 Proof test set-up for HiC2025(Y1)
For Y1 version only connect the multimeter to terminals 1 and 4.
Termination Board
HiC2025
Zone 0, 1, 2
Div. 1, 2
Zone 2
Div. 2
Multimeter
(V)
Multimeter
(V)
1a, 1b
2a, 2b
-
+
11
14
+
-
-
+
5
1
-4
I
supply
1b
SL2
5a
5b
SL1
8a
7a
Multimeter
(V)
Passive
input
Input sensor
(4-wire Tx
externally
powered)
Active
input
Input sensor
(2-wire Tx
loop powered)
Logic
solver
analog
input
Current output or
Voltage output or
Current sink
24 V DC
Power
supply
4 mA to 20 mA
4 mA to 20 mA
Tip
The easiest way to test HiC devices is by using a stand-alone HiCTB**-SCT-***-**-**
termination board. In this test, it is not necessary to disconnect the wiring of the existing
application. Faults in a subsequent wiring can be avoided.

Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
Maintenance and Repair
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6 Maintenance and Repair
Maintaining, Repairing or Replacing the Device
In case of maintenance, repair or replacement of the device, proceed as follows:
1. Implement appropriate maintenance procedures for regular maintenance of the safety loop.
2. While the device is maintained, repaired or replaced, the safety function does not work.
Take appropriate measures to protect personnel and equipment while the safety function
is not available.
Secure the application against accidental restart.
3. Do not repair a defective device. A defective device must only be repaired by
the manufacturer.
4. If there is a defect, always replace the device with an original device.
Danger!
Danger to life from missing safety function
Changes to the device or a defect of the device can lead to device malfunction.
The function of the device and the safety function is no longer guaranteed.
Do not repair, modify, or manipulate the device.

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Functional Safety KCD2-STC-(Ex)1(.SP)(-Y1), HiC2025(Y1)
List of Abbreviations
7 List of Abbreviations
ESD Emergency Shutdown
FIT Failure In Time in 10-9 1/h
FMEDA Failure Mode, Effects, and Diagnostics Analysis
sProbability of safe failure
dd Probability of dangerous detected failure
du Probability of dangerous undetected failure
no effect Probability of failures of components in the safety loop that have
no effect on the safety function. The no effect failure is not used for
calculation of SFF.
not part Probability of failure of components that are not in the safety loop
total (safety function) Probability of failure of components that are in the safety loop
HFT Hardware Fault Tolerance
MTBF Mean Time Between Failures
MTTR Mean Time To Restoration
PCS Process Control System
PFDavg Average Probability of dangerous Failure on Demand
PFH Average frequency of dangerous failure
PLC Programmable Logic Controller
PTC Proof Test Coverage
SFF Safe Failure Fraction
SIF Safety Instrumented Function
SIL Safety Integrity Level
SIL (SC) Safety Integrity Level (Systematic Capability)
SIS Safety Instrumented System
T1Proof Test Interval