Web site Information on Circuit Breaker 2

[Carl221]

Can any one provide any good web sites on Circuit Breaker design? I would prefer a tutorial web site as it would assist me in my project design.

Thank you.

Carl

 

[nihar]

Dear Carl 221,

It is very good to know and appreciate your interest in the subject of CB design. You can go on

http://www.abb.com

to find some details. Basically the primary thing you need for the design is the voltage level and the short circuit current. You also need to design your CB to see whether it withstands wind pressure (i.e basically cantilever strength of the CB insulator is to be checked)After doing the short circuit analysis you need to know that whether the cantilever strength is sufficient to withstand that force also.
Contactors of CB, the method of arc quenching, Transient recovery voltage, Rate of rise of recovery voltage of the arc quenching medium are also some of the factors needed to be taken into account. Hope some of these primary information is helpful to you. Best of Luck.
Bye.
Regards,
Nihar S. Raj

 

[nihar]

In addition to my mail above do keep in mind whether the system in which you are going to install your breaker is earthed or not. As the insulator height and the first pole to clear factor depends on it. If there is solidly grounded system we generally take first pole to clear factor as 1 or 1.1 but if the soil resistivity is high and earthing is not proper we take it as 1.5.
Bye.

 

[tgott]

You didn't say whether you were looking for power circuit breakers or household breakers. For household

http://www.howstuffworks.com/circuit-breaker2.htm.

Also see

http://www.tpub.com/neets/book3/8i.htm

http://search.barnesandnoble.com/booksearch/isbnInquiry.asp?userid=290H28L7L2&btob=Y&isbn=082479821X

 

[cuky2000]

In general, all circuit breakers are design to interrupt current. They could be design base on voltage range (low voltage, medium voltage high voltage), Interrupting technology (Thermomagnetic, Vacuum, Gas, Oil, electronic, etc), Construction (Live tank, dead-tank), etc.

If you could be more specific, you will increase your chance to get more help.

 

[Carl221]

Thank you guys,

The information provided has been very helpful. I appreciate all your tips.

Carl

 

[GRPatel]

Carl,
Circuit breaker design has two aspects.
1. You can be aprt of the circuit breaker manufacturer and developing a new circuit breaker. In that case you need to know the arcing phenomenon and its interruption, the mechanism design and lot of mechanical as well as dielectric issues.
2. You could be a user of a circuit breaker. In that case CB design is whay type of circuit breaker you may use for your typical application. In that case to know what could be your problem and for that what Cb is to be used, you need expertise. What is generally known as application engineering. For example, if you need to use Cbs at altitude higher than 1000m, a standard circuit breaker may not be suitable. In such case you may select one which can meet those requirements of higher altitudes. The important factor is that you should know that altitude is a point to be considered while selecting a CB. In absence of that knowledge, you may miss this point and may not select (design) a correct CB.

You have to tell what is your interest?

 

[jbartos]

Suggestion: Visit

http://www.doble.com/services/cservices3.htm#technical reference guide

for "Other reference material available includes tutorials held at Doble Conferences, such as the Circuit Breaker Tutorial (1992)"

 

Nothing much is being said about earthing of MV and LV switchgears, why? In most cases CBs are enclosed in some cushion or insulator kind of a structure with some metal components inside for switching whenever there is a fault. How are these metal structures inside the breaker earthed.

 

[cuky2000]

Dear Palafala,

There are several European breakers designed for MV and HV that integrate the circuit breaker and grounding switches in the same structure. For MV application often and enclosed with SF6 in a single pole per phase arrangement with common grounding bus is the switchgear chassis that required to be solidly grounded. I am not aware of ANSI manufacturer that have similar product.

Even thought there are progress in the ANSI/IEC harmonization, there are national issues and practices that require more time too be accepted. One of those combos (breaker/SW) MV Air-Insulated Switchgears is the AX-1 manufactured in Sweden and recently promoted in the US. For additional reference see the enclose site.

http://195.84.253.57/ax1/

[sub]NOTE:
I would like to share few experiences and general though that may explain why the silent on grounding related with circuit breakers.

1- Many engineers are used to different earthing practices such as ANSI and IEC. Even though there is universal similarities, there are also major differences in this matter as follow:

2- Switches status (including grounding devices) in the US must be visually inspected while in the IEC marketplace external position indicator for the switch status is acceptable.

3- Utilities in the US have jurisdiction to operate interconnected breaker and the disconnect switch in owner own substation and have to be installed in accordance with their typically ANSI specification and safety rules. Externally visually operated mechanism may have difficulty to be approved.

4- Manual operated mechanism in conventional grounding switch or jumper cable connected with clamps is widely accepted in the US in AIS substations, but not often used in MV metalclad switchgear assembly.

5- It is very common in EIC use grounding switches in MV, HV AIS and extensively used in GIS installation.

6- New devices and technologies may experience difficulty of acceptance probably for conflict of interest with local manufacturer, technological risk and concern associated with potential law suit in case of failure without any backup other than the manufacturer test report and manufacturer liability typically limited to 10% of the cost of the equipment purchase order.

 

Dear Cuky

If circuit breakers have to be earthed internally, how do you think this can be achieved especially LV and MV breakers.

 

[cuky2000]

Dead tank breakers are manufactured for high voltage. LV and MV could be installed in dead-front enclosure and that could be observed in a typical manufacturer product catalog.

What is not too obvious is how the dead-tank are earthing internally. Dead thanks are build with external metallic vessel were the interrupting mechanism is hold for one or more insulator bolted to the metal vessel and filled with SF6. In addition the rod that operate the interrupting mechanism have a portion insulated to avoid accidentally connection to the line potential.

MV barkers consist in s vacuum or SF6 bottle supported and isolated to the metal parts.

I hope this could help your question

 

[GRPatel]

Palafala,
The dead tank circuit breakers are now being used to integrate the breakers with other components of the substation. They can be earth switches, disconnectors (isolator), CTs etc. Thay are similar to GIS. You may visit

http://www.abb.com.

They have product PASS which can be sen on their website.