bus bar type tests
TRANSCRIPT
Total 4730 registered membersLog in .. ..Translate RSS Feed
Home•Sitemap
Power Electric Directory
Power Electric Links
Advertise With Us
Sponsorship
ePlusMenuCAD™•F.A.Q.
Order Your Licence
Screenshots
Download•Design Documentation
Electrical Software
Electric Power Books
Electrical Engineering
General Knowledge LV-HV
Technical Guides
Basics of Energy
Relays
Heating Systems
Learning AutoCAD
Power Substations
College Records
AutoCAD Video Training
Knowledge
Theorems And Laws
Page 1 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Electrical Formulas
Electrical Machines
Technical Articles•Submit Article
Categories
About Us•
Search our website... GO
15
Share
Email It!Posted by ecsanyi on Tuesday, March 9, 2010 at 8:00 pm | Technical Articles | Categories | Submit Article
Busbar Technical Specification
5,461 views
Page 2 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Busbar Technical Specification
Copper busbars are normally part of a larger generation or transmission system. The continuous rating of the main components such as generators, transformers, rectifiers, etc., therefore determine the nominal current carried by the busbars but in most power systems a one to four second short-circuit current has to be accommodated.
The value of these currents is calculated from the inductive reactances of the power system components and gives rise to different maximum short-circuit currents in the various system sections.
. Performance under Short-circuit Conditions
Busbar trunking systems to BS EN 60439-2 are designed to withstand the effects of short-circuit currents resulting from a fault at any load point in the system, e.g. at a tap off point or at the end of a feeder run. .
Rating under Short-circuit Conditions
The withstand ability will be expressed in one or more of the following ways:
short-time withstand rating (current and time)1.
Page 3 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
peak current withstand rating2.conditional short-circuit rating when protected by a short-circuit protective device (s.c.p.d.)3.
These ratings are explained in more detail:
1. Short-time Withstand Rating
This is an expression of the value of rms current that the system can withstand for a specified period of time without being adversely affected such as to prevent further service. Typically the period of time associated with a short-circuit fault current will be 1 second, however, other time periods may be applicable.
The rated value of current may be anywhere from about 10kA up to 50kA or more according to the construction and thermal rating of the system.
2. Peak Current Withstand Rating
This defines the peak current, occurring virtually instantaneously, that the system can withstand, this being the value that exerts the maximum stress on the supporting insulation.
In an A.C. system rated in terms of short-time withstand current the peak current rating must be at least equal to the peak current produced by the natural asymmetry occurring at the initiation of a fault current in an inductive circuit. This peak is dependent on the power-factor of the circuit under fault conditions and can exceed the value of the steady state fault current by a factor of up to 2.2 times.
3. Conditional Short-circuit Rating
Short-circuit protective devices (s.c.p.ds) are commonly current-limiting devices; that is they are able to respond to a fault current within the first few milliseconds and prevent the current rising to its prospective peak value. This applies to HRC fuses and many circuit breakers in the instantaneous tripping mode. Advantage is taken of these current limiting properties in the rating of busbar trunking for high prospective fault levels. The condition is that the specified s.c.p.d. (fuse or circuit breaker) is installed up stream of the trunking. Each of the ratings above takes into account the two major effects of a fault current, these being heat and electromagnetic force.
The heating effect needs to be limited to avoid damage to supporting insulation. The electromagnetic effect produces forces between the busbars which stress the supporting mechanical structure, including vibrational forces on A.C. The only way to verify the quoted ratings satisfactorily is by means of type tests to the British Standard. .
Page 4 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Type Testing
Busbar trunking systems are tested in accordance with BS EN 60439-2 to establish one or more of the short circuit withstand ratings defined above. In the case of short-time rating the specified current is applied for the quoted time. A separate test may be required to establish the peak withstand current if the quoted value is not obtained during the short-time test. In the case of a conditional rating with a specified s.c.p.d. the test is conducted with the full prospective current value at the trunking feeder unit and not less than 105% rated voltage, since the s.c.p.d. (fuse or circuit breaker) will be voltage dependent in terms of let through energy. .
Application
It is necessary for the system designer to determine the prospective fault current at every relevant point in the installation by calculation, measurement or based on information provided e.g. by the supply authority. The method for this is well established, in general terms being the source voltage divided by the circuit impedance to each point. The designer will then select protective devices at each point where a circuit change occurs e.g. between a feeder and a distribution run of a lower current rating. The device selected must operate within the limits of the busbar trunking short-circuit withstand.
The time delay settings of any circuit breaker must be within the specified short time quoted for the prospective fault current. Any s.c.p.d. used against a conditional short-circuit rating must have energy limitation not exceeding that of the quoted s.c.p.d. For preference the s.c.p.d. recommended by the trunking manufacturer should be used. .
Voltage Drop
The requirements for voltage-drop are given in BS 7671: Regulation 525-01-02. For busbar trunking systems the method of calculating voltage drop is given in BS EN 60439-2 from which the following guidance notes have been prepared.
Voltage Drop
Figures for voltage drop for busbar trunking systems are given in the manufacturer’s literature.
The figures are expressed in volts or milli-volts per metre or 100 metres, allowing a simple calculation for a given length of run.
The figures are usually given as line-to-line voltage drop for a 3 phase balanced load.
The figures take into account resistance to joints and temperature of conductors and assume the system is fully loaded.
Page 5 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Standard Data
BS EN 60439-2 requires the manufacturer to provide the following data for the purposes of calculation, where necessary:
R20
the mean ohmic resistance of the system, unloaded, at 20ºC per metre per phase
X the mean reactance of the system, per metre per phase
For systems rated over 630A:
RT the mean ohmic resistance when loaded at rated current per metre per phase
Application
In general the voltage drop figures provided by the manufacturer are used directly to establish the total voltage drop on a given system; however this will give a pessimistic result in the majority of cases.
Where a more precise calculation is required (e.g. for a very long run or where the voltage level is more critical) advantage may be taken of the basic data to obtain a more exact figure.
Resistance – the actual current is usually lower than the rated current and hence the resistance of the conductors will be lower due to the reduced operating temperature. . Rx = R20 [1+0.004(Tc - 20)] ohms/metre and Tc is approximately Ta + Tr
1.
where Rx is the actual conductor resistance
Ta is the ambient temperature
Tr is the full load temperature rise in ºC (assume say 55ºC)
Power factor – the load power factor will influence the voltage drop according to the resistance and reactance of the busbar trunking itself. The voltage drop line-to-line ( ∆v) is calculated as follows:
2.
∆v = √ 3 I (R x cos Φ + X sin Φ) volts/metre
where I is the load current
Page 6 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Rx is the actual conductor resistance (Ω/m)
X is the conductor reactance (Ω/m)
Cos Φ is the load power factor
sin Φ = sin (cos-1 Φ )
Distributed Load – where the load is tapped off the busbar trunking along its length this may also be taken into account by calculating the voltage drop for each section. As a rule of thumb the full load voltage drop may be divided by 2 to give the approximate voltage drop at the end of a system with distributed load. .
3.
Frequency – the manufacturers data will generally give reactance (X) at 50Hz for mains supply in the UK. At any other frequency the reactance should be re-calculated. . Xf = x F/50
. where Xf is the reactance at frequency F in Hz
4.
.
Source: Siemens Barduct Busbar Specification
.
Related articles
Line Protection With Distance Relays•Short Circuit Parameters in Low Voltage AC Circuits•Arc-resistant low voltage switchgear•General about motors•The Power Factor•
Be nice and share this article with others! How to use all these nice buttons?
Page 7 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Recommend 6 people recommend this.
Posted by: ecsanyi on Tuesday, March 9, 2010 at 8:00 pm Tagged with: busbar, busbar trunking, distributed load, en 60439-2, fault current, frequency, insulation, peak current, Power factor, reactance, resistance, rms, short circuit, type testing, voltage drop, withstand rating
Turn Your Thoughts Into Words
Tell us what you're thinking... we care about your opinion! and oh, not to forget - if you want a picture to show with your comment, go get a free Gravatar!
Name (required)
Mail (will not be published) (required)
Website
Page 8 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
CAPTCHA Code *
Submit Comment
Comments RSS Feed
Comments
One Response to “Busbar Technical Specification”
atiq says:29 September, 2011 at 12:07
I need a formula that how can i select the copper bus bar size according to the ampere ,for example i am having 630 amp/phase
Reply
1.
SUbscribe To Technical Articles•
7 Reasons to subscribe and receive
technical articles and updates via email:
Subscribe
Delivered via Google Feedburner
Page 9 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Electrical Engineering | Ads•
Electrical Engineering | Sponsors•
Electrical Engineering Articles•
Recent
Most Read
Comments
Superconducting transformers
Largest Tesla Coil Ever Built
ePlusMenuCAD 10 RC1 – New Release
ABB Power Transformers – A guide to manufacturing
Light Pollution
Line Protection With Distance Relays
UPS design criteria and selection
The New ETS4: Easy, Fast, Open
Arc-resistant low voltage switchgear
What is PowerLogic System?
Comparison Between Vacuum and SF6 Circuit Breaker viewed 25,517 times
ANSI standards for protection devices viewed 21,451 times
ANSI/IEC Relay Symbols viewed 19,689 times
Transformer heating and cooling viewed 14,042 times
Protection relays – important informations viewed 8,728 times
Maintenance Of SF6 Gas Circuit Breakers viewed 8,253 times
PLC-Based Monitoring Control System for Three-Phase Induction Motors Fed by PWM Inverter viewed 8,195 times
Gas-Insulated Switchgear Type 8DN8 viewed 7,710 times
Page 10 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Substation, Its Function And Types viewed 7,069 times
Air Insulated Substations – Bus/Switching Configurations viewed 7,063 times
Are Variable Frequency Drives Useful? - WATTS NEW
[...] PLC-Based Monitoring Control System for Three-Phase Induction Motors Fed by PWM Inverter (csanyigroup.com) [...]
mumbi masase
thank so much for your explanation.i think it has answered all my question.
Dattatraya
Its nice. I got several information. I have one request for u.. Can U pls send me some Electrical & Electronics books to my mail id.
Dattatraya
I like it... want more electrical details can u send to my mail id pls..
Wilson
Treba mi teorija, radim zavrsni iz frekventnih regulatora (:
Article Categories•
ANSI Standards AutoCAD Cables Energy And Power ePlusMenuCAD High Voltage Hydropower IEC Standards
Page 11 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
KNX Lighting Low Voltage Medium Voltage Motors Power Substations Programmable Logic Controller Protection Relays SCADA Solar Energy Tips & tricks Transformers Updates And Announcements Variable Speed Drives Wind Power
Links•
Direktorijum Kvalitetnih Srpskih Sajtova
Visitors•
Page 12 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Live Traffic Feed•
See your visitors in RealTime! Get the Free Live Traffic Feed Get Feedjit Now!
A visitor from Dubai viewed "Busbar Technical Specification | CsanyiGroup" 0 secs ago
A visitor from Dar Es Salaam, Dar es Salaam viewed "AutoCAD Video Training | CsanyiGroup" 1 min ago
A visitor from Muscat, Masqat viewed "Motor Operation Efficiency Under Abnormal Conditions | CsanyiGroup" 7 mins ago
A visitor from Brisbane, Queensland left "ANSI/IEC Relay Symbols | CsanyiGroup" via std.iec.ch 9 mins ago
A visitor from Svrljig left "Nothing found for Vesti" via elektroenergetika.info 11 mins ago
A visitor from Svrljig viewed "Nothing found for Vesti" 12 mins ago
A visitor from Seoul, Seoul-tukpyolsi viewed "Gas-Insulated Switchgear Type 8DN8 | CsanyiGroup" 13 mins ago
A visitor from Hyderabad, Andhra Pradesh viewed "Comparison Between Vacuum and SF6 Circuit Breaker | CsanyiGroup" 15 mins ago
A visitor from Fredrikstad, Ostfold viewed "SIEMENS: Short Circuit Calculations | CsanyiGroup" 16 mins ago
A visitor from Mumbai, Maharashtra viewed "ANSI code 50BF - Breaker failure |
Page 13 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification
Portal Content•
ePlusMenuCAD | Development
Electric Power Books
Technical Articles
Electrical Design Software & Tools
AutoCAD | Video Training
Engineering Knowledge
Translate to your language•
Hindi
Arabic
Filipino
Spanish
EEP - Electrical Engineering Portal•
EEP is engineering portal dedicated to electrical science and education and it's core purpose is to spread knowledge and educate power engineers in fields of power substations, industrial automation, low voltage, medium voltage and high voltage applications etc.
EEP - Electrical Engineering Portal
Support Us•
Make a small donation, show us that you care about our work! Make a donation
Copyright © 2003-2010 Csanyigroup - Electrical Engineering Portal • Privacy Policy
Page 14 of 14Busbar Technical Specification | CsanyiGroup
4/10/2012http://www.csanyigroup.com/busbar-technical-specification