Hazards Analysis, Code Compliance & Procedure Development

Services to identify process safety hazards and facilitate compliance with established standards and codes.

Combustible Dust Testing

Laboratory testing to quantify dust explosion and reactivity hazards

Flammable Gas & Vapor Testing

Laboratory testing to quantify explosion hazards for vapor and gas mixtures

Chemical Reactivity Testing

Laboratory testing to quantify reactive chemical hazards, including the possibility of material incompatibility, instability, and runaway chemical reactions

ISO Accreditation and Scope
Fauske & Associates fulfills the requirements of ISO/IEC 17025:2017 in the field of Testing
DIERS Methodology

Design emergency pressure relief systems to mitigate the consequences of unwanted chemical reactivity and account for two-phase flow using the right tools and methods

Deflagrations (Dust/Vapor/Gas)

Properly size pressure relief vents to protect your processes from dust, vapor, and gas explosions

Effluent Handling

Pressure relief sizing is just the first step and it is critical to safety handle the effluent discharge from an overpressure event

Thermal Stability

Safe storage or processing requires an understanding of the possible hazards associated with sensitivity to variations in temperature

UN-DOT

Classification of hazardous materials subject to shipping and storage regulations

Safety Data Sheets

Develop critical safety data for inclusion in SDS documents

Biological

Model transport of airborne virus aerosols to guide safe operations and ventilation upgrades

Radioactive

Model transport of contamination for source term and leak path factor analysis

Fire Analysis

Model transport of heat and smoke for fire analysis

Flammable or Toxic Gas

transport of flammable or toxic gas during a process upset

OSS consulting, adiabatic & reaction calorimetry and consulting

Onsite safety studies can help identify explosibility and chemical reaction hazards so that appropriate testing, simulations, or calculations are identified to support safe scale up

Mechanical, Piping, and Electrical

Engineering and testing to support safe plant operations and develop solutions to problems in heat transfer, fluid flow, electric power systems

Battery Safety

Testing to support safe design of batteries and electrical power backup facilities particularly to satisfy UL9540a ed.4

Hydrogen Safety

Testing and consulting on the explosion risks associated with devices and processes which use or produce hydrogen

Spent Fuel

Safety analysis for packaging, transport, and storage of spent nuclear fuel

Decommissioning, Decontamination and Remediation (DD&R)

Safety analysis to underpin decommissioning process at facilities which have produced or used radioactive nuclear materials

Laboratory Testing & Software Capabilities

Bespoke testing and modeling services to validate analysis of DD&R processes

Nuclear Overview

Our Nuclear Services Group is recognized for comprehensive evaluations to help commercial nuclear power plants operate efficiently and stay compliant.

Severe Accident Analysis and Risk Assessment

Expert analysis of possible risk and consequences from nuclear plant accidents

Thermal Hydraulics

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Environmental Qualification (EQ) and Equipment Survivability (ES)

Testing and analysis to ensure that critical equipment will operate under adverse environmental conditions

Laboratory Testing & Software Capabilities

Testing and modeling services to support resolution of emergent safety issues at a power plant

Adiabatic Safety Calorimeters (ARSST and VSP2)

Low thermal inertial adiabatic calorimeters specially designed to provide directly scalable data that are critical to safe process design

Other Lab Equipment and Parts for the DSC/ARC/ARSST/VSP2 Calorimeters

Products and equipment for the process safety or process development laboratory

FERST

Software for emergency relief system design to ensure safe processing of reactive chemicals, including consideration of two-phase flow and runaway chemical reactions

FATE

Facility modeling software mechanistically tracks transport of heat, gasses, vapors, and aerosols for safety analysis of multi-room facilities

Blog

Our highly experienced team keeps you up-to-date on the latest process safety developments.

Process Safety Newsletter

Stay informed with our quarterly Process Safety Newsletters sharing topical articles and practical advice.

Resources

With over 40 years of industry expertise, we have a wealth of process safety knowledge to share.

Recent Posts

Next Generation Cable Testing Using LIRA®

Posted by The Fauske Team on 03.09.16

 

Introduction
Electric cables are essential to all industrial processes. They serve several functions, including power transmission and supply, instrumentation and control. Despite their importance, cables typically receive little attention — they are considered passive, enduring components that are very reliable. In reality, like most other components, cables are susceptible to degradation. Cable aging may lead to increased electrical noise, worsened electrical properties, and eventually cable failures. Cable failures have caused safety concerns, resulted in accidents, lost revenue, and even lead to power loss and plant shutdowns.

In general, cables are often composed and specified by three key parameters: the conductor, insulation, and jacket. The primary component of concern in regards to cable degradation is the insulation material around the metallic conductor. The insulation is protected by the jacket (or outer material) of the cable. Additionally, depending on the voltage and application, cable construction can also include other components such as shields and semiconductor tape.LIRA Testing of an Underground Electrical Transmission Circuit

Cable reliability is a growing concern in industry, and is both economic and regulatory driven. Cable related requirements have resulted from a fairly recent shift in regulatory compliance. Specifically, there are new cable related requirements for nuclear power plant life extensions where aging has become a factor for cables in safety-critical applications. This issue is discussed in the Nuclear Regulatory Commission (NRC) report Generic Aging Lessons Learned (NUREG 1801). Cable aging continues to be an important research topic for the NRC and EPRI. A key question for cable users regarding cable reliability is how can we evaluate cable health based upon non-destructive field measurements?

There are several test methods available to evaluate cable performance. Some methods stress the cable beyond their normal operating conditions — sometimes to failure. Other methods provide an indication of the overall performance of the cable, but do not identify localized damage. Most testing methods also require the cables under test to be de-terminated.

The LIne Resonance Analysis (LIRA®) cable condition monitoring test overcomes these obstacles and provides both an indication of the overall cable health as well as locally degraded areas. LIRA is a nondestructive evaluation tool that does not over-stress the cable; it uses a low 5 volt DC peak-to-peak (Vpp) signal to perform its’ evaluation. Unlike most traditionally used testing techniques, LIRA performs both global and local assessments of the test cable. Additionally, the test cable does not need to be disconnected from its source to perform LIRA testing and the test is completed in minutes. Leaving the cable connected eliminates a step that could result in issues with cable performance after the test during normal operation: the cable termination or re-termination.

How Does LIRA Work?

LIRA is based on transmission line theory. A transmission line can be viewed as any two conductors with an applied voltage. A common type of transmission line is overhead cables lining many streets which transmit power from a generator to various loads. Another type of transmission line is a coaxial cable or two strips on a printed circuit board.

LIRA transmits a variable frequency wave (signal) and calculates the line impedance as a function of the frequency; this technology is commonly referred to as frequency domain reflectometry or FDR. As the transmitted signal encounters changes in impedance resulting from changes in the type of cable insulation, splices, degraded insulation, or other, a reflected signal is returned to LIRA. The magnitude of the reflected signal determines the relative severity of the identified impedance change(s) while the phase angle of the reflected signal corresponds to the location of the identified impedance change(s). Combined, these two measurements characterize the localized impedance change.

The identified localized impedance changes can be normal (i.e., well installed splices) or not. Abnormal impedance changes are due to certain cable stressors. Cable stressors include: higher than normal thermal conditions, mechanical damage, water/humidity, chemical interactions, and radiation among others. An assessment of the identified impedance change can then be performed to determine what, if any actions are required. For example, The test results may indicate that local cable repairs are warranted rather than requiring complete cable replacement.

In addition to localized insulation damage, LIRA also provides an overall assessment of the cable’s global condition by an established LIRA Health Index (LHI). With this information, a, assessment of the condition of the cable under test can be established.

Lira Testing Setup
Testing a cable with LIRA is quick and simple. The only requirement for operation is for the cable to be deenergized. The cable does not need to be de-coupled or de-terminated. For example, a breaker can be opened and the test leads connected to the stabs. Then the two LIRA test leads are connected to two metal cores of the cable (for example, two conductors or one conductor and a shield) using alligator clips, a coaxial cable connector or similar devices. Depending on the length of the test cable, a typical LIRA test will take about three minutes.

Example LIRA Testing Results
The following is an example of LIRA testing results. These test results are from a short (150 ft) low voltage twisted pair cable system with thermal damage to the cable insulation at 78 feet. This damage location is clearly seen when observing the LIRA Signature Plot, as shown in the following graph.

LIRA Signature Plot – Thermal Damage Identification

The LIRA Signature plot is a normalized trend that shows LIRA signal strength (labeled as “Gain (dB)”) as a function of the length of the cable (labeled as “Distance (ft)”). For LIRA, it is typical to have a signal peak at the start of a cable and a similar peak at the end of the cable. The peak at 78 feet represents the location of the thermal damage. This relationship is used to determine areas of potential impedance related performance issues based upon the magnitude of the peak. The X-axis is used to identify the location of the area of interest using the X-axis scale, where 0 is the location of where the LIRA test unit was attached to the cable under test.

Insight into the cause of the impedance change can be found in the DNORM relationship. The following is the DNORM plot for the example LIRA test case.

LIRA DNORM Plot – Thermal Damage identificationThe LIRA DNORM plot compliments the LIRA Signature plot by providing additional information about identified impedance changes along the cable. The DNORM plot provides a normalized graphical interpretation of the finding along the measured cables length, without the start and end terminations shown. The direction of the severity can be used to further determine the cause in some cases. A negative impedance variation, for example, could mean water ingression in cables exposed to water environments and positive impedance could be due to mechanical or thermal damage.

To determine the health of the cable under test, the LIRA Health Index (LHI) is used. LHI provides a classification of the Health of the cable and actions:

1) Green (good) – No actions required
2) Yellow (caution) - Further study advised
3) Red (warning) - Action required

A key indicator of the LIRA Health Index (LHI) is the LIRA Delta-G (LDG) parameter. The following graph is the LDG for the example test cable discussed above.

LIRA Delta-G (LDG) Plot – Thermal Damage IdentificationBased upon the type of insulation of the cable for this example, a a LDG value of 24 x 10-3 corresponds to a cable health of “Yellow” and a classification of “Further study required”. It should be noted that the LHI is currently under development.

For more information or to discuss further, please email us at info@fauske.com, (630) 323-8750.  www.Fauske.com

Subscribe to FAI's "Nuclear Technical Bulletins"

#cable testing

 

 

 

Topics: cable health, cable aging, cable failure, lira, electric cable, cable test, cable reliability, testing

cta-bg.jpg

Is My Dust Combustible?

A Flowchart To Help You Decide
Download Now