Current Interrupter Tutorials

Current Interrupter Tutorials Facts, Definitions, Uses Etc.

Circuit Breaker
An electromagnetic device that opens a circuit automatically when current exceeds a predermined value. It is capable of interrupting large values of fault power MVA resulting from the faults on the power system. It consists of current carrying contacts called electrodes which, under predetermined conditions, separate to interrupt the circuit. An arc is struck between them when the contacts are separated. This arc is extinquished either by lengthening the arc, cooling the arc, or splitting the arc. Due to this, the arc resistance increases resulting in the system voltage becoming unable to maintain the arc and the arc gets extinguised.

HRC Fuse
High Rupturing Capacity cartridge fuse is a good interrupting device because it gives a fast fault clearing and exhibits property of cut-off. It is useful in low and medium voltage installation to provide overload and short-circuit protection. The fuse element is of copper alloyed with tin. Its characteristics vary with the type of material and the shape of fuse element. The rated current of the fuse is the current which it can carry continously without deterioration.

Switchgear
The name given to a family of devices covering a wide range of equipment concerned with switching and interrupting the currents during normal and abnormal conditions. The equipment associated with controlling, protecting, regulating and measuring also belong to the switchgear family. It includes switches, fuses, Circuit breaker, isolator, relays, Control panel, metering panels lighting arresters, Current transformer, Potential transformer, and other associated items. The circuit breakers are assited by other components of the protective scheme. A switch is used for opening and closing the circuit. Fuse is used for over-current protection. The purpose of switching and protection is served by the swithgear. A circuit breaker is the switching and interrupting device in a switchegear.

Reactors
The purpose, of reactors incorporated in circuit breakers is to limit the short-circuit current flowing to a safe value thus providing protection of instruments. The concist of large coils of high self-inductance and very low resistance. Main type of reactors are magnetically shielded reactor, and the shielded reactor.

Answer all Frequent Questions About Circuit Breaker
1. The function of protective relay in a circuit breaker is to close the contacts when the actuating quantity reaches a certain predetermined value.
2. Low voltage circuit breakers have rated voltages of less than 1000 volts.
3. When A high voltage Alternating current circuit breaker is tested for endurance, it is tested for at least 1000 opening closing operations.
4. For high voltage Alternating Current circuit breaker, the rated short circuit current is passed for 3 three second.
5. Vacuum is not a type of the contactor for circuit breaker.

Current Interrupter Tutorials

Ratings of a Circuit Breaker in and Outdoor

We need the ratings of a circuit breaker whether indoor or outdoor before the design done. All the designs is based on where you are located in the planet earth it is because of the voltage system mattered. Following below links is a free PDF file as requested in the previous articles I do hope it will answers all the request from the followers of this site.

circuit Breaker Standards
Preferred Ratings for Indoor Circuit Breakers with Voltage Range Factor K>1.0, Rating structure changes have caused some
concerns and misunderstandings because the
ratings assigned to circuit breakers, in accordance
with the 1987 ratings edition



Rating Structure of High Voltage Circuit Breakers
Considerations for selection of Circuit Breakers for Capacitive Current Switching and TRV
Ratings for capacitance current switching
1) Rated overhead line charging current;
2) Rated isolated cable and isolated shunt capacitor bank switching current;
3) Rated back to back cable and isolated shunt capacitor bank switching current;
4) Rated transient inrush current peak;
5) Rated transient inrush current frequency;




Generator Switchgear With IEEE
Gas Turbine Generators, Steam Turbine Generators,Diesel Electric Generators, Hydro Electric Generators,Combined Cycle Plants
Referring to the one-line representations above, there are important issues over safely interrupting short circuit faults in a
generator circuit which cannot be normally handled by distribution class circuit breakers.


Comparison between ANSI/IEEE and IEC
Voltage levels are different, standard current ratings are different, and system kA interrupting
levels are also quite different. It is common for European designers to keep continuous currents and kA levels lower by increasing the system voltage and allowing system impedance to be higher. In North America, the opposite theory seems to be often (but not always) applied.


Benefits of Enclosed Distribution Substations
Explore AIS Construction, Distribution Substation,Bus Design Considerations,  Necessary to connect remote power, control and sensing cables to outboard apparatus to control house.


METAL-CLAD VACUUM SWITCHGEAR
This advanced switchgear line is completely factory built, wired and assembled. Each cubicle may contain the circuit breaker, bus bars, primary
and secondary disconnecting devices, instrument transformers, instruments and relays, secondary
wiring and other necessary corn...


INTERNATIONAL STANDARD IEC and IEEE
Overhead, pad-mounted, dry vault, and submersible automatic circuit reclosers and fault interrupters for alternating current systems up to 38 kV

Free Tutorial : Circuit Breaker The Muscle of Electrical Power System

Electrical power system is like a human being having a heart and a muscle, we already knew that the heart of electrical power system is electrical power transformer, but on this article we will be focusing on the muscle of electrical power system called the electrical circuit breakers.

From well known scholar Electrical Engineer C.S.D. of our company said. A circuit breakers are almost present in all electrical installations for circuit protection, some are using fuses with equivalent function to save the circuitry from electrical faults and other abnormal conditions.

Faults are possible in tree branches touching a electrical power line causing short circuit can cause tremendous amount of electrons to flow on wires and other equipment that the later cannot carry without breakage, thus, the need to cut the supply is necessary to avoid sizable damage on the electrical system.

During a bad weather, a strong wind can blow an overhead power line causing it to swing and touch the other live electrical wires and thereby resulting to a large current to rush on both lines. The same may happen a branch of tree  comes in contact with a power line temporarily or permanently. On such abnormal conditions, an instrument capable of cutting and restoring electrical power within a very minimal time is badly needed.

This is a job for electrical circuit breakers and electrical fuses, it automatically opens the circuit when overloading and short circuit happens, therefore preventing large amounts of currents to continue and harm the equipment by fire, melting or disintegration.

Unlike Electrical fuses that can be utilized only once and must be replaced, circuit breakers can be used several times and can be reset manually or remotely using supervisory control and data acquisition or SCADA.

Electrical circuit breakers vary in sizes, constructions, structure, and more but has to be strong enough like a muscle to be able to disconnect the circuit during abnormal conditions without damaging itself. An example of which is the high voltage circuit breaker inside a electrical power substation.

On the other hand a mini circuit breaker is usually used on residential, commercial and also industrial buildings with low supply voltage.

More about Electrical Circuit breaker free pdf and tutorials found below

Fuses and circuit breaker


Circuit breaker sizing on faults calculations


 Definitions and its uses of Circuit breakers
Circuit breakers elements, types of circuit breakers, principles and operations, breakers requirements, particular of C.breakers, its ratings


CircuitBreakers for equipments
The overload sensing is done with the aid of a thermal bimetal which
has the advantage of being immune to high inrush currents and line
transients.

Free pdf Electronics Circuit Breaker and Circuit Design

Electronic circuit realization of the logistic map
An electronic circuit realization of the logistic difference equation is presented using analog electronics. The behaviour of the realized system is evaluated against computer simulations of the same. The circuit is found to exhibit the entire range of dynamics of the logistic equation: fixed points, periodicity, period doubling, chaos and intermittency. Quantitative measurements of the dynamics of the realized system are presented and are found to be in good agreement with the theoretical values. Some possible applications of such a realization are briefly discussed.
http://www.ias.ac.in/sadhana/Pdf2006Feb/PE1349.pdf



EECS 170D Integrated Electronics Circuit Design
Overview of design and fabrication of modern digital integrated circuits. Fabrication of CMOS process; transistor-level design simulation, functional characteristics of basic digital integrated circuits, different logic families including static and dynamic logic, layout and extraction of
digital circuits; automated design tools.
http://undergraduate.eng.uci.edu/documents/policy/publications/courseoutline/2007-2008/eecs/eecs%20170d.pdf



Ghost Stochastic Resonanec in an Electronics Circuit
This type of phenomenon is not possible within the framework of linear signal processing and deserves to be further explored experimentally. In this Letter we analyze the response of an nonlinearelectronic circuit which emulates the system in Chialvo et al., 2002 when it is driven by noise and by weak signals composed of multiple periodic tones.
http://www.chialvo.net/files/xx-2006-Calvo.pdf




Integrated Electronics Circuit Breaker IC
For hot-swap and power management applications. Today’s design engineers are faced with a variety of choices when selecting protection devices to meet their circuit or system’s design requirements Fuses, positive temperature coefficient (PTC) resistors, and electromechanical circuit breakers represent only a sampling of the technologies available to meet their needs. Each of these devices provides a different degree of security, ranging from simple short circuit protection to devices which offer active current limiting and remotely resettable operation.
http://focus.tij.co.jp/jp/lit/an/slua131/slua131.pdf



EE 310 – Electronic Circuit Design I
Prerequisites Topics are : Understanding and the ability to use linear algebra and complex variables in the solution of linear circuits, understanding of basic linear circuit constants and variables,
http://www.ee.psu.edu/acadaff/courses/ee_310_syllabus.pdf



EE 311 – Electronic Circuit Design II
Learning Outcomes: Develop an appreciation for different device properties and their use and limitations in circuit applications, understand the properties of different circuit and sub-circuit topologies and their appropriate use in amplifier design, understand the bandwidth constraints imposed by device and circuit capacitances, and the appropriate use of amplifier topologies to mitigate frequency response limitations. develop an appreciation for the analysis and design of different amplifiers such as basic onetransistor amplifiers, differential pairs, multistage amplifiers, and operational amplifiers.
http://www.ee.psu.edu/acadaff/courses/ee_311_syllabus.pdf

Grounding of industrial and Commercial Power system 2007, Harmonic Treatment in Industrial Power

Grounding of industrial and Commercial Power system 2007
how to select equipment for the ground of the neutral circuits. Connecting the frames and enclosures of electric apparatus, such as motors, switchgear, transformers, buses, cables, conduits, building frames, and portable equipment, to a ground system is addressed.
http://rapidshare.com/files/154859154/IEEEStd_142_2007_Grounding_of_Industrial_and_Commercial_Power_Systems.PDF


Grounding of Industrial and Commercial Power Systems 1991
This recommended practice has served electrical engineers seeking electrical system grounding information since the first edition in 1956. It reflects the experience and sound judgment of a working group made up of engineers active in the design and operation of electrical systems for industrial and commercial power systems.
http://rapidshare.com/files/154854801/IEEE_Std_142-1991_Grounding_of_Industrial_and_Commercial_Power_Systems.PDF




Harmonic Treatment in Industrial Power
When a voltage and/or current waveform is distorted, it causes abnormal operating conditions in a power system.
http://rapidshare.com/files/154862766/HARMONIC_TREATMENT_IN_INDUSTRIAL_POWER_.ppt



HIgh Voltage Circuit Breaker
This type of book is long overdue. For those of us who are involved in the design of these devices it has been a long road of learning.
http://rapidshare.com/files/154873328/High_voltage_circuit_breakers.pdf



Hands On ZigBee
Implementing with Microcontrollers, Its promise of providing a simpler, cheaper, more power-efficient WPAN (Wireless Personal Area Network) alternative to WiFi and Bluetooth has opened up new data collection possibilities in application areas from industrial controls to medical devices to intruder alarms. Yet, despite this widespread interest, there is still little information available that goes beyond detailing the spec itself.
http://go4link.com/lqfq2

CIRCUIT BREAKER SIZING ON FAULT CALCULATIONS

Prior to designing substation, you should have an anticipation plan before its to late one of the most important is the protective devices to your equipment transformer etc. So this articles content the definition of circuit breaker, the breaker rating based on the standard, its breaker sizing, and with example.

A. CIRCUIT BREAKER
Is a device :
- to open and close a circuit by non-automatic means
- to open the circuit automatically on a predetermined overload of current or during faults without damage to itself when properly applied within its rating.
- When the transformer primary reference current is equal or greater than 45 amperes or when there is more than one transformer in a substation, the protection will be by a power circuit breaker........................IEC











B. BREAKER RATINGS

1. Voltage Rating (Rated Maximum Voltage)
* the highest rms(root mean square) voltage, above nominal system voltage, for which the circuit breaker is designed, and is the upper limit of operation.
* 15 kV, 72.5 kV, 145 kV, 245 kV

2.Continuous Current Rating (Rated Continuous Current)
* Rated Continuous Current
* the designated limit of current in rms amperes at rated frequency w/c it shall be required to carry continuously without exceeding any of the limitations/conditions in a specified ambient temperature.
* Ambient temp. from -30 deg. C to 40 deg. C
* Altitude is not above 3300 ft (1000m)

3.KAIC Rating (Rated Short Circuit Current, K=1)
* Kilo-Ampere Interrupting Capacity (KAIC)
* the maximum amount of symmetrical current that the breaker can safely interrupt at rated maximum voltage -without injuring or damaging itself.

* KAIC = k X Rated Short-Circuit Current
where:
k = is the ratio of rated maximum voltage to the lower limit of the range of operating voltage.
= Vmax / Vmin

Modern Circuit Breakers, k = 1.0

KAIC = k X Rated Short Circuit Current
= Rated Short Circuit Current

Old Circuit Breakers, k>1.0
Condition 1: If RMV > OV > (1/k) x RMV
then,
KAIC = Rated Isc x (Rated Maximum Voltage / Operating Voltage)

Condition 2: If OV < (1/k) x RMV then, KAIC is limited to Rated Isc x k KAIC = Rated Isc x k Example: Consider an indoor oilless circuit breaker having a rated short-circuit current of 37,000 A at rated maximum voltage of 15kV and K = 1.30. What is the symmetrical interrupting capability at an operating voltage at a.)13.2 kV? b.)11.5 kV? C. BREAKER SIZING
E/X Simplified Method


- E/X simplified procedure result may be compared with 100% of the circuit breaker KAIC rating where
X/R < 15 (X1/R1 for 3-phase faults) ((2X1 + Xo)/(2R1 + Ro) for SLG-faults) - If X/R is unknown, the E/X does not exceed 80% of the KAIC rating of the breaker. - For SLG – Faults, where it is greater than the 3-Phase Faults or Xo less than X1

C. SAMPLE PROBLEM

A SUBSTATION



1. Solve for the maximum fault duties at the 3-phase fault points.

2. Specify the Voltage Ratings, Continuous Current Ratings & KAIC Ratings of the circuit breakers.