Bus-bar System

Message from jimwkm@gmail.com. The following article may help you:

Ampacities and Mechanical Properties of Rectangular Copper Busbars

Introduction

"Busbar systems" refers to conductors that take the form of a bar or bars of copper conductor. The bars may be exposed or enclosed. The system may have one or more joints to assure proper length and configuration and one or more take-off points connected to end-use equipment.

The tables that follow provide ampacity of copper busbar conductors for sizes typically found in the USA under the temperature-rise conditions specified in the table, along with physical and mechanical properties. Also included are DC ampacity tables provided by ATIS (Alliance for Telecommunications Industry Solutions) for sizes and configurations typically found in the telecommunications industry.

For energy-efficiency considerations, the design of the busbar system should be based on a 30°C rise above ambient, or less. Temperature rises above 65°C are not recommended and are not energy-efficient.

A more complete guide to busbars and design considerations can be found in the U.K. Copper Development Association's Publication No. 22, Copper for Busbars. The book can be ordered in print form through our Energy Efficiency Publications List (UK22).

The ampacity tables presented here are for rectangular busbars of Copper No. 110 whose surface condition is similar to that of busses at typical installations. Ampacities were calculated using a nominal conductivity of 99% IACS and should also be applicable to other coppers with the same electrical conductivity. Listed for 60 Hz at temperature rises of 30, 50, and 65°C above ambient, they were determined from accurate emissivity coefficients measured by calorimetric techniques. The methods are described in "Electrical Coils and Conductors", by H.B. Dwight (McGraw-Hill Publishing Co., New York, 1945, Chapter 19).

Ampacity Calculations - Accurate emissivity is essential because it is used to calculate the heat dissipated by radiation, a factor in the general equation for ampacity:

where I is ampacity (amp), WR is heat dissipated by radiation (watts), WC is heat dissipated by natural convection (watts), and R is resistance (ohms) at operating temperature and 60 Hz.

Table 1. Ampacities of Copper No. 110 Busbars - Ampacities in this table are for busbars having an emissivity of 0.4.

This was observed on samples exposed for 60 days in an industrial environment, and it is probably identical to that of busbars in service.

Direct-current ampacities may differ from AC ampacities because of AC skin effect: where I_DC is DC ampacity (amp), I_AC is AC ampacity at 60 Hz (amp), and S is the skin effect ratio at 60 Hz.

Table 2. Mechanical Properties of Copper No. 110 Busbars - This table lists properties useful in calculating such characteristics as stiffness and deflection that are often required by designers of busbar systems.

Table 3. Quick Busbar Selector - Knowing the ampacity, designers and estimators can get the approximate busbar size. Ampacity of the busbar selected must then be verified by checking table 1.

Table 4. Effect of Emissivity and Number of Busses on Ampacity - Data here show how higher emissivities improve ampacity. Multiple busses also affect ampacity in a nonlinear relationship. Ampacity may be raised by increasing heat dissipation through the use of convection cooling or surface treatments. Surface treatments which emissivity are available.

DC Ampacity Tables - These tables list the DC ampacity of copper busbars in the sizes and configurations most often found in the telecommunications industry. They have been provided by the Alliance for Telecommunications Industry Solutions (ATIS) for the convenience of the reader.

CDA Busbar Economic Analysis Program

US Sources of Busbar

Typical Busbar Sizes

Another option is to present the problem to an electrical switchgear manufacturer and let them price for the work wanted. In this way, local regulations will be maintained and the liability rests with them upon delivery, assuming there is a receipt for the work paid for.

Hi

Generally there are tables supplied by the manufacturer of the basbar becuse due to working temperture, construction, Copper's alloy compositions, ... etc the rating will vary but for simple estimation you can use the data 2Amp per mm-squire current carrying capacity for cupper busbar. This can serve as starting point.

I am new to this forum, can you include on this discussion aluminum bus-bar. I am into thermography and have been conducting thermal scanning inspection on aluminum bus bar. Thanks.

hiee!! can you pl tell me which international standard you follow for inspection of bus bar by thermography test...

Dear,

u can visit MERLINGERIN.COM. It provides useful inf. regarding BUS BAR SYSTEM.

Tks.

can anyone suggest busbar voltage limitaions