This document provides information on medium voltage HRC fuses. It describes the key features of HRC fuse-links, which have high rupturing capacity and can limit short-circuit currents. The fuse-links are used to protect transformers, capacitor banks, cables, and overhead lines. The document discusses fuse-link and fuse-base types, specifications, applications, selection criteria based on rated voltage and current, installation guidelines, and compliance with various standards.
Cable sizing to withstand short circuit currentLeonardo ENERGY
In a cable a short circuit causes very extreme stresses which are proportional to the square of the current:
• A temperature rise in the conducting components subjected to current flow such as conductor, screen, metal sheath, armour. Indirectly the temperature of adjoining insulation and protective covers also increases,
• electro-magnetic forces between the current-carrying components.
The temperature rise is important for its effect on ageing, heat pressure characteristics etc., and should be limited to a permissible short-circuit temperature. The thermo-mechanical effects of the current shall also be considered.
For a given short-circuit duty therefore the short-circuit capacity of a cable installation is to be investigated with respect to all these parameters. For multi-core cables in most instances the thermal effect - related to the magnitude of fault current and clearance time - is the critical parameter, since the cable will normally have enough mechanical strength. With single-core cables however, in addition, the mechanical effect - related to the magnitude of the peak short-circuit current - is of such significance that, next to the thermal, the mechanical with- stand of both cable and its supports is to be investigated.
Also accessories must be rated with respect to thermal and mechanical short-circuit stresses.
The short-circuit withstand of a cable system is not quantitatively defined with regard to permissible number of repeated short circuits, degree of deformation or destruction or impairment quality. It is expected, however, that a cable installation will remain safe in operation and that any deformation remains within tolerable limits even after several short circuits.
Cable sizing to withstand short circuit currentLeonardo ENERGY
In a cable a short circuit causes very extreme stresses which are proportional to the square of the current:
• A temperature rise in the conducting components subjected to current flow such as conductor, screen, metal sheath, armour. Indirectly the temperature of adjoining insulation and protective covers also increases,
• electro-magnetic forces between the current-carrying components.
The temperature rise is important for its effect on ageing, heat pressure characteristics etc., and should be limited to a permissible short-circuit temperature. The thermo-mechanical effects of the current shall also be considered.
For a given short-circuit duty therefore the short-circuit capacity of a cable installation is to be investigated with respect to all these parameters. For multi-core cables in most instances the thermal effect - related to the magnitude of fault current and clearance time - is the critical parameter, since the cable will normally have enough mechanical strength. With single-core cables however, in addition, the mechanical effect - related to the magnitude of the peak short-circuit current - is of such significance that, next to the thermal, the mechanical with- stand of both cable and its supports is to be investigated.
Also accessories must be rated with respect to thermal and mechanical short-circuit stresses.
The short-circuit withstand of a cable system is not quantitatively defined with regard to permissible number of repeated short circuits, degree of deformation or destruction or impairment quality. It is expected, however, that a cable installation will remain safe in operation and that any deformation remains within tolerable limits even after several short circuits.
The Electrical Installation Guide has been written for electrical professionals who must design safe and energy efficient electrical installation, in compliance with international standards such as the IEC 60364
�The sample calculations shown here illustrate steps involved in calculating the relay settings for generator protection.
�Other methodologies and techniques may be applied to calculate relay settings based on specific applications.
Transformer vector group_test_conditionsSARAVANAN A
Test Conditions for various vector groups commonly under use are listed along with pictorial representation. Assuming the reader has sufficient exposure to transformer winding connections.
Transformer Vector Group Test conditions
YNd1, YNd11, Dyn11, YNyn0and more
A fuse is a short piece of metal, inserted in the circuit, which melts when excessive current flows through it and thus breaks the circuit. The fuse element is generally made of materials having low melting point, high conductivity and least deterioration due to oxidation e.g., silver, copper etc. It is inserted in series with the circuit to be protected. Under normal operating conditions, the fuse element is at a temperature below its melting point. Therefore, it carries the normal current without overheating. However, when a short-circuit or overload occurs, the current through the fuse increases beyond its rated value. This raises the temperature and fuse element melts (or blows out), disconnecting the circuit protected by it. In this way, a fuse protects the machines and equipment from damage due to excessive currents.
High Voltage On-Site Testing with Partial Discharge Measurement (Cigre 502)AHMED MOHAMED HEGAB
During the life cycle of high voltage (HV) apparatus or systems many tests and measurements are performed to characterize the insulation condition. The results of these tests and
measurements should be compiled in a “life data record”, which supplies information on trends of diagnostic indicator values. The HV on-site test with partial discharge (PD) measurement has an intermediate position between routine tests and in-service monitoring measurements (on-line or offline)
The Electrical Installation Guide has been written for electrical professionals who must design safe and energy efficient electrical installation, in compliance with international standards such as the IEC 60364
�The sample calculations shown here illustrate steps involved in calculating the relay settings for generator protection.
�Other methodologies and techniques may be applied to calculate relay settings based on specific applications.
Transformer vector group_test_conditionsSARAVANAN A
Test Conditions for various vector groups commonly under use are listed along with pictorial representation. Assuming the reader has sufficient exposure to transformer winding connections.
Transformer Vector Group Test conditions
YNd1, YNd11, Dyn11, YNyn0and more
A fuse is a short piece of metal, inserted in the circuit, which melts when excessive current flows through it and thus breaks the circuit. The fuse element is generally made of materials having low melting point, high conductivity and least deterioration due to oxidation e.g., silver, copper etc. It is inserted in series with the circuit to be protected. Under normal operating conditions, the fuse element is at a temperature below its melting point. Therefore, it carries the normal current without overheating. However, when a short-circuit or overload occurs, the current through the fuse increases beyond its rated value. This raises the temperature and fuse element melts (or blows out), disconnecting the circuit protected by it. In this way, a fuse protects the machines and equipment from damage due to excessive currents.
High Voltage On-Site Testing with Partial Discharge Measurement (Cigre 502)AHMED MOHAMED HEGAB
During the life cycle of high voltage (HV) apparatus or systems many tests and measurements are performed to characterize the insulation condition. The results of these tests and
measurements should be compiled in a “life data record”, which supplies information on trends of diagnostic indicator values. The HV on-site test with partial discharge (PD) measurement has an intermediate position between routine tests and in-service monitoring measurements (on-line or offline)
Underground Cable Accessories
Elastimold® offers the industry's most complete package for managing underground cable connections.
Broad Product Range..
Elastimold accessories, available from 5kV to 138kV, connect, ground, splice, terminate and protect underground cable.
Elastimold Innovation
Elastimold’s long, innovative history includes pioneering such products as extended and repair elbows, jacket seal elbows, and shrink-fit joints.
CIRCUIT BREAKER
A circuit breaker is an automatically-operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high voltage circuits feeding an entire city.
ABB MV Medium Voltage Transformers - Voltage Transformers VT's
Up to 40.5kV Medium Voltage MV Indoor Transformers VT's
ABB Power Products
ABB MV Medium Voltage Transformers - Voltage Transformer Features
Indoor dry type, cast resin insulated transformers for medium voltages (MV). ABB transformers are suitable for measuring and protection of MV medium voltages with up to 2 secondary windings.
ABB MV Medium Voltage Transformer : Unearthed Double-Pole Voltage Transformer ABB KGUG
ABB KGUG voltage transformer for medium voltage systems has all parts of its primary winding, including terminals, insulated from the earth at a level corresponding to its rated insulation level. ABB KGUG voltage, double-pole insulated transformers are casted in epoxy resin and designed mostly for insulation voltages of 24kV to 36kV.
ABB KGUG Voltage Transformer
ABB MV Medium Voltage Transformer : Indoor Voltage Transformer Double Pole ABB TDC
ABB TDC voltage transformer for medium voltage systems has all parts of its primary winding, including terminals, insulated from the earth at a level corresponding to its rated insulation level . Indoor dry type, cast resin insulated medium voltage (MV) transformer for measuring and protection with up to 2 secondary windings.
ABB TDC Voltage Transformer
ABB MV Indoor Voltage Transformer : Indoor Voltage Transformer ABB TJP
ABB TJP voltage transformer is a single phase voltage transformer which is intended to have one end of its primary winding directly earthed. Indoor dry type, cast resin insulated medium voltage transformer for measuring and protection with up to 2 secondary windings. With or without fuses. Most electrical standards available. Reconnectable MV medium voltage versions available.
ABB TJP Voltage Transformer
ABB MV Indoor Voltage Transformer : Indoor Voltage Transformer Single Pole ABB KGUGI
ABB KGUGI voltage transformer is 36kV indoor dry type, cast resin insulated medium voltage transformers for measuring and protection with up to 2 secondary windings. With or without fuses. Most electrical standards available. Reconnectable versions available.
ABB KGUGI Voltage Transformer
ABB MV Indoor Voltage Transformer : Indoor Voltage Transformer Single Pole ABB TJC
ABB TJC is a single phase voltage transformer which is intended to have one end of its primary winding directly earthed. Indoor dry type, cast resin insulated medium voltage transformer for measuring and protection with up to 2 secondary windings. With or without fuses. Most electrical standards available. Reconnectable MV medium voltage versions available.
Isolation Procedures for Safe Working on Electrical Systems and Equipment by the JIB | solation Procedures for Safe Working on Electrical Systems and Equipment
This chart shows the safe isolation procedure that you should use when working on electrical systems and equipment.
You'll receive a printed copy of this from your Training Provider, but it's also here as a handy reference to keep electronically.
THE RULES OF SAFE ISOLATION ARE:
Obtain permission to start work (a Permit may be required in some situations)
Identify the source(s) of supply using an approved voltage indicator or test lamp
Prove that the approved voltage indicator or test lamp is functioning correctly
Isolate the supply(s)
Secure the isolation
Prove the system/equipment is DEAD using an approved voltage indicator or test lamp
Prove that the approved voltage indicator or test lamp is functioning correctly
Put up warning signs to tell other people that the electrical installation has been isolated
Once the system/equipment is proved DEAD, work can begin
Uploaded by THORNE & DERRICK LV HV Jointing, Earthing, Substation & Electrical Eqpt | Explosive Atmosphere Experts & ATEX IECEx.
THORNE & DERRICK based in the UK are international distributors of LV, MV & HV Cable Installation, Jointing, Substation & Electrical Equipment.
Since 1985, T&D have established an international reputation based on SERVICE | INTEGRITY | TRUST.
Contact us for 3M, ABB, Alroc, AN Wallis, CATU, Cembre, Centriforce, CMP, CSD, Elastimold, Ellis Patents, Emtelle, Euromold, Filoform , Furse, Lucy Electric & Zodion, Nexans, Pfisterer, Polypipe, Prysmian, Roxtec, Sicame, WT Henley.
Software Delivery At the Speed of AI: Inflectra Invests In AI-Powered QualityInflectra
In this insightful webinar, Inflectra explores how artificial intelligence (AI) is transforming software development and testing. Discover how AI-powered tools are revolutionizing every stage of the software development lifecycle (SDLC), from design and prototyping to testing, deployment, and monitoring.
Learn about:
• The Future of Testing: How AI is shifting testing towards verification, analysis, and higher-level skills, while reducing repetitive tasks.
• Test Automation: How AI-powered test case generation, optimization, and self-healing tests are making testing more efficient and effective.
• Visual Testing: Explore the emerging capabilities of AI in visual testing and how it's set to revolutionize UI verification.
• Inflectra's AI Solutions: See demonstrations of Inflectra's cutting-edge AI tools like the ChatGPT plugin and Azure Open AI platform, designed to streamline your testing process.
Whether you're a developer, tester, or QA professional, this webinar will give you valuable insights into how AI is shaping the future of software delivery.
Connector Corner: Automate dynamic content and events by pushing a buttonDianaGray10
Here is something new! In our next Connector Corner webinar, we will demonstrate how you can use a single workflow to:
Create a campaign using Mailchimp with merge tags/fields
Send an interactive Slack channel message (using buttons)
Have the message received by managers and peers along with a test email for review
But there’s more:
In a second workflow supporting the same use case, you’ll see:
Your campaign sent to target colleagues for approval
If the “Approve” button is clicked, a Jira/Zendesk ticket is created for the marketing design team
But—if the “Reject” button is pushed, colleagues will be alerted via Slack message
Join us to learn more about this new, human-in-the-loop capability, brought to you by Integration Service connectors.
And...
Speakers:
Akshay Agnihotri, Product Manager
Charlie Greenberg, Host
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Search and Society: Reimagining Information Access for Radical FuturesBhaskar Mitra
The field of Information retrieval (IR) is currently undergoing a transformative shift, at least partly due to the emerging applications of generative AI to information access. In this talk, we will deliberate on the sociotechnical implications of generative AI for information access. We will argue that there is both a critical necessity and an exciting opportunity for the IR community to re-center our research agendas on societal needs while dismantling the artificial separation between the work on fairness, accountability, transparency, and ethics in IR and the rest of IR research. Instead of adopting a reactionary strategy of trying to mitigate potential social harms from emerging technologies, the community should aim to proactively set the research agenda for the kinds of systems we should build inspired by diverse explicitly stated sociotechnical imaginaries. The sociotechnical imaginaries that underpin the design and development of information access technologies needs to be explicitly articulated, and we need to develop theories of change in context of these diverse perspectives. Our guiding future imaginaries must be informed by other academic fields, such as democratic theory and critical theory, and should be co-developed with social science scholars, legal scholars, civil rights and social justice activists, and artists, among others.
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
JMeter webinar - integration with InfluxDB and GrafanaRTTS
Watch this recorded webinar about real-time monitoring of application performance. See how to integrate Apache JMeter, the open-source leader in performance testing, with InfluxDB, the open-source time-series database, and Grafana, the open-source analytics and visualization application.
In this webinar, we will review the benefits of leveraging InfluxDB and Grafana when executing load tests and demonstrate how these tools are used to visualize performance metrics.
Length: 30 minutes
Session Overview
-------------------------------------------
During this webinar, we will cover the following topics while demonstrating the integrations of JMeter, InfluxDB and Grafana:
- What out-of-the-box solutions are available for real-time monitoring JMeter tests?
- What are the benefits of integrating InfluxDB and Grafana into the load testing stack?
- Which features are provided by Grafana?
- Demonstration of InfluxDB and Grafana using a practice web application
To view the webinar recording, go to:
https://www.rttsweb.com/jmeter-integration-webinar
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
2. 1. FEATURES
− High rupturing capacity
− Short−circuit current limiting
− Low rated minimum breaking current (Imin)
− Low switching overvoltages (Um)
− Can be used with switch disconnector (it is fitted with
a medium−size striker pin)
− Dimensions acc. to DIN and IEC Standards.
2. APPLICATIONS
The HRC (high rupturing capacity) fuse−links are used
to protect transformers, capacitor banks, cable and
overhead lines against short−circuits. They protect
switchgears from thermal and electromagnetic effects of
heavy short−circuit currents by limiting the peak current
values (cut−off characteristic) and interrupting the currents
in several milliseconds.
The type BWMW fuse−links interrupt overload
currents greater than Imin (for the Imin values refer to Table 1).
In situations where overloads lower than Imin are to be
interrupted by the protective system, a switch−
disconnector fitted with an overcurrent protecting device
is to be used together with the type BWMW fuse−links.
BWMW fuse−links can be used with type BWMP,
BWMPE, BWMPNS, BWMPNW and BPS−01 fuse−bases
as well as type OR5 or NALF switch−disconnectors.
3. ENVIRONMENTAL OPERATING
CONDITIONS
BWMW fuse−links can be operated under the following
environmental conditions:
− on indoor and outdoor equipment,
− at ambient temperatures of −30oC to +40oC,
− at relative humidity of ambient air of 100% at
a temperature of +20oC.
4. DESIGNATIONS VERSIONS
4.1 BWMW−fuse−links numbering system
The numbering system for the BWMW fuse−links has
four alphanumerical sections as shown in the diagram
below.
4.2 BWMP−fuse−base numbering system
The numbering system for the BWMP fuse−base has
four alphanumerical sections as shown in the diagram
below.
BWMW − 7,2 / 100 – 1
Fuse−link Rated Rated Additional
type voltage current designation:
BWMW 7,2−7,2 kV 3,15 A
12−12 kV 6,3 A
24−24 kV 10 A
36−36 kV 16 A
20 A
25 A
31,5 A
40 A
56 A
63 A
80 A
100 A
Type BWMW 7,2
/63;80;100 A
Fuse−links
version that
is 292 mm long
BWMP E − 7,2 / 56
Fuse base Insulator Rated Rated
type type voltage current
BWMP E − resin 7,2−7,2 kV 40 A
NS − outdoor 12−12 kV 50 A
porcelain 24−24 kV 56 A
standing−insulator 36−36 kV 63 A
NW − outdoor 100 A
porcelain (Refer to Table 2)
suspented insulator
No designation − indoor
porcelain insulator
A fuse−link when mounted on its fuse−base makes
a complete fuse. For a list of fuse bases refer to Table 2.
5. COMPLIANCE WITH
STANDARDS
The fuse−links meet the requirements of the
following Standards:
− Polish Standard PN−92/E−06110
− Polish Standard PN−86/E−06114
− International Standard IEC 282−1: 1994
− International Standard IEC 644 of 1979
− German Standard DIN 43625
− Russian Standard GOST 2213: 1979
The fuse−bases meet the requirements of the
following Standards:
− Polish Standard PN−77/E−06110
− International Standard IEC 282−1: 1994
− German Standard DIN 43625
6. HOW TO ORDER
Order by specifying the product name, type symbol,
rated voltage, rated current and quantity.
All additional demands which are not listed in this
Catalogue should be agreed with the manufacturer by
means of an Inquiry where the sources of requirements
(regulations, standards, etc.) are to be specified.
6.1 Order example
1. Type BWMW−7.2/100 High Rupturing Capacity Fuse−
link for a rated voltage of 7.2 kV, a rated current of
100 A
2. Type BWMPNW−12/56 Outdoor Fuse−base for a rated
voltage of 12 kV, a rated current of 56 A. − 20 pcs
3. Type BWMW−36/20 High Rupturing Capacity Fuse−
link for a rated voltage of 36 kV, a rated current of 20 A
4. Type BWMPNS−36/40 Outdoor−Standing Fuse−base
for a rated voltage of 36 kV, a rated current of 40 A. −
20 pcs.
2 ABB
3. 7. SPECIFICATIONS
7.1 Fuse−links specifications
Table 1.
10%
The resistance are to be measured by a electrical bridge method or technical metod using measuring instrument
with accuracy class not worse than 0.5% at an ambient temperature of t = 20oC ±2oC.
ABB 3
5. Type BWMW high−rupturing−capacity fuse−link
F−L Striker Pin Characteristic
Striker Pin free stroke is 4 mm
Notes:
1. Contact End Caps: silver−plated brass
2. Deviations of dimensions with no tolerance specified shall be within ±3%.
ABB 5
6. 8. CONSTRUCTION AND
OPERATION
8.1 Construction and operation of fuse−links
A fuse−link consists of an insulation tube whose both
ends are terminated with end caps. Fuse elements are
made from specially profiled silver wire and are helically
wound on a porcelain winding stick. Additional fusible
element intended to control operation of the striker pin
is located in a coaxial hole of the stick. The fuse interior
is filled with arc−quenching material whose chemical
composition and granularity have been appropriately
chosen. The fuse−link is sealed at its both ends.
A spring−type striker pin is located in one end−cap
and its forced movement can be employed to trip an
operating mechanism of a switch−disconnector or to
trigger alarm and auxiliary circuits.
The fuse operation depends on automatic one−off
interruption of the fault current in the protected circuit
by melting of the fuse element and quenching the
electric arc produced in the fuse−link interior. The
operation is indicated by the striker pin which has now
moved to its tripped position.
The fuse−link limits the peak value of the short−circuit
current and in consequence effectively protects the
circuit against thermal and electromagnetic effects of
short−circuits.
8.2 Construction of fuse bases
The fuse−base consists of a steel beam fitted with
a protective earthing terminal and two indoor support
insulators. Two sets of contacts are mounted on the
upper side of the insulator. The set of contacts consists
of a contact spring, compression spring, and terminals.
9. PRINCIPLES OF FUSE−LINKS
SELECTION
9.1 Selection of rated voltage
The rated voltage for a fuse−link is to be selected in the
following way:
− if the fuse−link is to be operated in an earthed neutral
three−phase network, the rated voltage for the fuse−link
is to be equal to at least line−to−line voltage in the circuit
to be protected,
− if the fuse−link is to be operated in a single−phase
network, the rated voltage for the fuse−link is to be equal
to at least 115% of the highest voltage in the circuit to be
protected,
− if the fuse−link is to be operated in an insulated neutral
three−phase network or a network compensated by means
of earth fault neutraliser, the rated voltage for the fuse−
link is to be equal to at least 115% of the line−to−line
voltage in this network as double earth faults are possible.
It should be however noted that in situations where a
fuse−link featuring an excessive rated voltage has been
selected, excessively high voltages for the circuit under
consideration might occur. Refer to Table 1 for the limiting
overvoltage values for this family of fuse−links. Should it
be necessary to obtain more detailed data on the
overvoltages, please call the fuse manufacturer.
9.2 Selection of rated current
The rated current of a fuse−link is usually greater than
a long−term load for the circuit under consideration. While
selecting the rated current, the following should be taken
into account.
− long−term current load and operating overloads for
the circuit under consideration,
− transient overloads involved into such actions as
switching power on and off for such equipment as
transformers, electric motors, and capacitor banks,
− co−ordination with other devices intended to protect
the circuit under consideration.
The rated current is determined by heating of a single
fuse−link under free air conditions at an ambient
temperature of +10oC to +40oC.
In situations where the fuse−links are to be used in
enclosures, cabinets and at places and in a manner
making heat transfer more difficult or if the fuse−links are
to operate at an ambient temperature higher than +35oC,
lowering of the rated current value can be required to take
the actual conditions of heat transfer into account.
Refer to Table 3 for selection of fuse−links rated current
recommended for protecting transformers.
The selection presented above has been developed for a
transformer overloaded up to 1.5 In when a condition of
if01 > 12 In, is met, where:
i f01 − minimum current value corresponding to a pre−arcing
time of 0.1 sec.
I n − rated voltage of the transformer
12 In; 0,1 sec. − parameters of the assumed making current
for the transformer.
However, in situations where actual making current value
and waveform are known the fuse−link is to be selected
individually. Besides, when a transformer protecting system
is designed, the recommendations of IEC 787 Publication
of 1983 is to be taken into consideration.
It is suggested to test warm the equipment with fuses at
a load of 1.5 In for the transformer to be protected
particularly in cases where the correct selection is doubtful
or the fuses are installed in a manner and at places
(enclosures, cabinets, partitions, neat other heat sources,
at higher ambient temperatures, and etc.) worsening the
heat transfer. Section can be accepted as satisfactory if
the produced steady state temperature−rise limits do not
exceed the values permitted by respective standards.
6 ABB
7. Table 3. Selection of fuse−links rated current for transformers
Rated voltage of the transformer [kV]
Transformer
rated power
[kVA]
6 10 15 20 30
Rated voltage for the fuse−link
7,2 12 17,5 24 36
Fuse−link rated current [A]
20 6,3 6,3 3,15 3,15 ¾
30 6,3 6,3 6,3 3,15 3,15
50 10 6,3 6,3 6,3 3,15
75 16 10 6,3 6,3 6,3
100 20 16 10 6,3 6,3
125 20 or 25 16 10 or 16 10 6,3
160 25 20 16 10 10
200 40 20 16 16 10
250 56 31,5 20 16 10
315 56 31,5 or 40 25 20 16
400 63 40 or 56 25 or 31,5 20 16
500 80 56 40 25 25
630 100 63 56 31,5 25
800 ¾ 80 63 40 31,5
1000 ¾ 100 63 50 40
1250 ¾ ¾ ¾ 63 ¾
9.3. Selection of the fuse−link rated current for electric
motors – protection coordination principles
9.3.1 Selection of the fuse−link rated current for
electric motors in a direct−on−line starting
arrangement
Electric motors by protected with switches (contactors,
switch disconnectors) fitted with operating mechanisms
and are additionally protected by fuses of specially selected
characteristics. The fuse−link must be fitted with striker
pin whose mechanical energy is used to trigger the switch
disconnector.
Difficulty with selection of the rated current for fuse−links
intended to protect electric motors in a direct−on−line
starting arrangement consists in the necessary immunity
of fuses to consecutive overload pulses of the motor−
starting−up current.
For the fuse selection requirements, tests, and
regulations concerned with motor protection systems refer
to IEC 644 Standard: 1979 and its Polish equivalent PN−
86/E−06114.
The Types BWMW for rated voltages of 7.2 kV and 12
kV and rated current range of 63 A to 100 A meet the
requirements of the Standards mentioned above with
respect to their time−current curves and are featured by
their k−factors determined by tests for a pre−arcing time
of 10 sec. with characteristic accuracy taken into
consideration according to these Standards. For the values
of k−factors refer to Table 4. The k−factor is to be used for
determining the overload curve of fuse−link.
According to these Standards, the k−factor values
determined for a pre−arcing time of 10 sec. is valid for
motor starting−up periods of 5 to 60 sec if the rate of motor
starts is not greater than 6 per hour and no more than two
consecutive starts per hour are made provided that the
peak value of the starting−up current is not greater than
the full−load value multiplied by a factor of 6.
ABB 7
8. Table 4. k−factor Values
Fuse−link
Fuse type
Un Dimension“L” k−factor for particular In
kV mm 63 A 80 A 100 A
BWMW − 7,2 7,2 292 0,56 0,55 0,56
442 0,60 0,60 0,60
BWMW − 12 12 537 0,60 0,59 0,59
According to these Standards, the k−factor values
determined for a pre−arcing time of 10 sec. is valid for
motor starting−up periods of 5 to 60 sec if the rate of motor
starts is not greater than 6 per hour and no more than two
consecutive starts per hour are made provided that the
peak value of the starting−up current is not greater than
the full−load value multiplied by a factor of 6.
Thus,
‰ ‰
k · IIk · Iand If10
r f10 ns 6
where:
I− motor starting−up current,
r Table 5. if and irmax, values against s−up periods
Ins − motor full−load current
if01 − fusing current as read in the fuse−link time−current
characteristic for a pre−arcing time of 10 seconds.
If the actual starting−up period differs from 10 seconds,
a value of if is to be read in the fuse−link time−current
characteristic for a pre−arcing time equal to the actual
starting−up period (within a range of 5 to 60 seconds)
and substituted in the formula.
To make the selection of fuse easier, Table 5 lists fusing
current values, if, and corresponding motor starting−up
current values, irmax against starting−up periods 5, 10, 20,
30, 40, and 60 seconds.
Un In Dimension“L” Starting−up periods in seconds
kV A mm A 5 10 20 30 40 60
63 I f 210 190 170 160 155 145
I r max =k×If 118 106 95 90 87 81
80 292 I f 300 270 240 230 215 205
I r max 165 148 132 126 118 113
100 I f 400 360 320 300 285 270
7,2 I r max 224 201 179 168 159 151
63 I f 220 200 180 170 165 160
I r max 132 120 108 102 99 96
80 442 I f 300 270 240 230 215 205
I r max 180 162 144 138 129 123
100 I f 370 330 300 280 265 250
I r max 222 198 180 168 159 150
63 I f 220 200 180 170 165 160
I r max 132 120 108 102 99 96
12 80 I f 300 270 240 230 215 205
557 I r max 177 159 142 136 127 121
100 I f 380 340 305 285 275 260
I r max 224 200 180 168 162 153
8 ABB
9. Example
„Select a fuse−link of 12 kV rated voltage to protect
a motor having a starting−up current of Ir = 190 A and
a starting−up period tr = 12 seconds for a rate of motor
starts not greater than 6 per hour".
First, you should compare the value of Ir to respective
ones listed in Table 4. In our case these are 10 s and 20 s.
By comparing the respective values it can be seen that the
proper fuse−link is that having a current rating of 100 A
because
Ir max 10(200) > Ir (190) > Ir max 20(180)
Accurate check can be done by calculating:
Ir
k
If = = = 322 A
(Where the value of k−factor has been read in Table 2
for 12 kV/100 A)
and reading the pre−arcing time amounting to 14 s (thus,
greater than tr = 12 s) from the appropriate time−current
curve (here 12 kV/100 A).
The full−load of the motor for the selected fuse−link
should not exceed a value of
Ir
6
190
0,59
190
6
Ins ‰ ‰ ‰ 31,7 A
Note: The Types BWMW−7,2 kV / 63−100 A are available
in two sizes of dimension „L” = 292 mm and 442 mm. Those
longer ones (442 mm) should be selected if smaller rated
minimum fusing current I min offers a special attraction
while by selecting the shorter ones (292 mm) the fuses
can be installed at a location of smaller space.
The fuse−links selected in this way are intended for
operating under standard environmental conditions
specified for the types BWMW. Should it be necessary to
install the fuse−links together with other devices in a closed
enclosure it is necessary to check whether the ambient
temperature of the enclosure interior does not exceed the
permissible value of +35oC and, if necessary, a fuse−link
of successive higher level of the rated current should then
be selected.
9.3.2 How to select the rated current of fuse−link
Intended to protect electric motors in an
indirect starting arrangement
Because the fuse−links intended to protect electric
motors in an indirect starting arrangement are overloaded
with excessive pulses of the motor−starting−up current,
their rated current may be lower than that for the motor
protection in a direct−on−line starting arrangement.
Provision for keeping fuse−link temperature permanently
within the permissive temperature−rise limits in long−term
duty of the motor to be protected irrespectively of the
operating overloads is a decisive selection factor.
To provide satisfactory operation without simultaneous
fast deterioration of the fuse−links in the motor circuit in
an indirect starting arrangement, the fuse−link rated
current should be always greater than the most severe
load with operating overloads being taken into account.
Therefore, it is recommended to select a rated current
equal to the motor full−load current multiplied by a factor
of 1.5 to 2.
9.4 How to select the rated breaking current (Iws) of
a fuse−link
The rated breaking current (Iws) of a fuse−link is to be
equal to at least an initial fault current (Ip) at the location
the fuse−link is installed.
9.5 How to Select the Rated Peak Current
(determining the required electromagnetic
strength of the devices protected by means of
fuse−links)
According to the requirements of Polish Standard
PN−74/E−05002, the rated peak current insz should fulfil the
following inequality condition
insz Š iu
where: iu − (prospective) impulse short circuit current.
In situations where the fuse limits the value of prospective
impulse short circuit current, a product Iogr × h is to be substituted
instead of iu in the relation presented above.
Where:
Iogr − fuse cut−off current for the prospective impulse short
circuit current.− Iu corresponding to the largest designed fuse−
link.
h − a factor depending on the fuse cut−off current characteristic
band width. In situations where no accurate data is available, a
h−factor = 1.5 is to be accepted.
ABB 9
10. Fig. 1 Cut−off current characteristics for the types BWMW−7,2; 12; 24; 36 kV
high rupturing capacity fuse−links
10 ABB
11. time
current
Fig. 2 Time−current characteristics for the types BWMW−7,2/3.15−100 A
(63 A excluded; dimension L = 292 mm); BWMW−12/3,15−40A and 63 A and 80 A Fuse−links
I3 Current Designations:
❍ − BWMW−7.2 kV Fuse−links
● − BWMW−12 kV Fuse−links
time
current
Fig. 3 Time−current characteristics for the types BWMW−7,2/63A (dimension L = 292 mm);
BWMW−24/3,15−63A; BWMW−12/56 and 100 A; and BWMW−36/3,15−40 A Fuse−links
I3 Current Designations:
❍ − BWMW−7.2 kV Fuse−links − BWMW−24 kV Fuse−links
● − BWMW−12 kV Fuse−links − BWMW−36 kV Fuse−links
ABB 11
12. Type BWMP indoor high−rupturing−capacity fuse−base
Two 15 mm dia. holes
Notes:
1. Earthing Terminal; tinned steel.
2. Connections: silver−plated brass
3. Contact Springs: silver−plated brass
4. Deviations of dimensions with no tolerance specified shall be within ±3%.
Fuse−base Dimensions
type A3 A2 A1 B2 B1 C1 ÆD
BWMP−36/40
380±1 688±1 538±1
329±1 394±1
BWMP−24/63
BWMP−24/50 300±1 593±1 443±1 239±1 304±1
BWMP−12/100 380±1 688±1 538±1
0
105
85
75
BWMP−7,2/100 300±1 593±1 443±1
BWMP−12/56 180±1 445±1 293±1 159±1 224±1
BWMP−7,2/56 55±1 345±1 193±1 35±1
12 ABB
13. Type BWMPE indoor high−rupturing−capacity fuse−base
Two 15 mm dia. holes
Notes:
1. Earthing Terminal; tinned steel.
2. Connections: silver−plated brass
3. Contact Springs: silver−plated brass
4. Deviations of dimensions with no tolerance specified shall be within ±3%.
ÆD
70
56
Fuse−base Dimensions
type A3 A2 A1 B2 B1 C1
BWMPE−36/40 380±1 688±1 538±1 326±1 398±1
BWMPE−24/63
BWMPE−24/50 300±1 593±1 443±1 236±1 308±1
BWMPE−12/100 380±1 688±1 538±1 0
BWMPE−7,2/100 300±1 593±1 443±1
156±1 228±1
BWMPE−12/56 180±1 445±1 293±1
BWMPE−7,2/56 55±1 345±1 193±1 35±1
ABB 13