Speciality Services (Busbars)

Busbars Specifications

What makes Powerbars and Control cc's busbars the most desirable in the industry is the precision and excellence by which the design, supply, manufacture (meticulous in cutting, drilling and welding procedures) customization and implementation (assembly on site, and custom fitting when alterations needs to be made on the standard shape because of external busbar frame and structure deviations) is executed.

Ferraz Switch before (left) and after switch installation (right).

Ferraz Switches.

The measures taken by Powerbars and Control cc which ensures the most sophisticated product are:

First and foremost A Pre Quote Site Assessment (during the open tender time) to ascertain what the prerequisite of the client is and if any further advice and alterations can be provided.

A. The Composition:

The design drawings specifically issued ‘For Construction’ will form the basis from which the Quality Management Plan will be developed in accordance with SABS1195-1978 section 5, and ‘Hold Points’ and ‘Witness Tests’ will be documented before the project commence. The purity and quality of the busbar material is the most important factor for Powerbars and Control cc in upholding an exceptional busbar standard and according to the SABS standards the coppers composition is as follow:

i.    Low Oxygen, High Conductivity, Tough Pitch, Electrical Copper busbars to exceptional standards of:

- BS EN 13601:2000 Cu-ETP CW004A

- BS EN 1652:1998 Cu-ETP CW004A

- BS 2870 : 1980 C101 (superseded by above Standards)

- DIN E-Cu (2.0060) 1787 17670


Metallurgical composition:

- Cu Min     99.9 %            - Ag Max     0.01 %

- O Max      0.04 %            - P Max       0.01%

- Zn Max     0.01 %            - Ni Max     0.01%

- As Max     0.01 %            - Sn Max     0.01%

- Pb Max     0.2 %              - Te Max     0.01%

**Please note that BS 1400 has been superseded before 1980.

ii.    All busbars rolled with width and thickness tolerances to SABS1195-1978 :

-  Width on 315mm wide and smaller segments         :    ±1.0mm

-  Width on 400mm wide and smaller segments         :    ±1.5mm

-  Thickness on 5mm thick segments                          :    ±0.2mm

-  Thickness on 15mm thick segments                        :    ±0.5mm

-  Thickness on 20mm thick segments                        :    ±0.5mm

-  Thickness on thicker segments                               :    ±5%

iii.    Busbars are ordered from the rolling mills in 6m lengths.

- There are also specific stacking and packing procedures to minimize deformations and deviations and will be accompanied by a laboratory certified metallurgical certificate.

- Lengths are stencil stamped on receival for quality plan purposes.

Powerbars student team working on the Re-installation of busbars on an epoxy type fiberglass frame at Luita, DRC in January 2011.

 

Transformer room with new transformers and cleaned busbars on a new non corrosive non conductive frame (left), anode and cathode to the plant (right).

B. During the manufacturing of the busbars:

i.   All busbar items are cut to length, while the material is sufficiently clamped and full length supported on a speed controlled, liquid cooled, radial saw, with a tungsten tipped blade for which the tooth pitch are specifically selected for copper within the following tolerances :


- Length to max. 3000mm long segments     :    ±1.0mm

- Length to max. 6000mm long segments     :    ±1.5mm

- All cuts 90° perpendicular to length          :    ±0.25°

ii.    The connection edges of busbar items are welded, machined on a ‘Turret Milling Machine’, 90° perpendicular to length, and angled according to specific welding procedure for the particular joint.

All this will be done to a fine finish.

iii.    Holes are only drilled while the material is sufficiently clamped and full length supported on a liquid cooled, ‘Vertical Borer’ with fluted ‘Carbide End Mills’, of which the cutting edges are specifically ground for copper.


-  Hole locations are marked with a collared template/parallel cylinder punch,

-  All holes larger than 18mm diameter will be 3-staged drilled,

-  All holes are centred within 1.0 mm from any reference on drill pattern,

-  All holes will be de-burred and chamfered to a fine finish.

iv.    All bends in busbar items are done on a 70T fixed installation, hydraulic bender with a stationary bending radius and vertical moving mandrill, from a horizontal position and full length support:


-  Angular speed adjustable to eliminate any surface cracks,

-  No pre-heating or material softening to disturb molecular structures or pitch -characteristics,

-  Replaceable bending radiuses to adapt to particular bend design,

-  All bends to withing ±.5°

Sanding of busbars before re assembly in transformer room to get rid of the copper corrosive and oxidation layer and to

increase surface area on a microscopic level to optimize conductivity.

C. The welding of copper busbar items :

i. All welding of busbars are according to AWS 5.6-ECu UNS W60189.

-  Welding procedures are developed for each type of weld depicted in the specific busbar design, and for every busbar thickness configuration as per ISO15614-6 part 6,

-  Each welding procedure is also documented and together with test-weld/s presented for testing by a certified laboratory as prescribed by the ISO15614-6 and ISO9606-3 (1999),

-  Each welding procedure is certified by an ECSA registered, Pr. Eng., with recognition from the S.A. Welding Institute,

-  Each operator/welder involved with a welding procedure is coded and certified by an ECSA registered, Pr. Eng., with recognition from the S.A. Welding Institute,

 

ii.    All materials to be welded are machined prepared :

-  All material edges to be welded are machined with a carbide milling bit.

-  V-groove angles will be to fine finish and angles within 0.5° tolerance

-  V-grooves are provided with temporary end-stop blocks, from BS EN 13601:2000 Cu-ETP CW004A material, and will be removed by machining.

-  If needed, in very rare conditions, if manual alterations are needed, then only a clean metal file will be used, not to allow contamination of the material with any metallurgical elements from abrasive materials, such as grinding disks, or sandpaper, to reduce the risks of welding defects.

 

iii.    All materials to be welded are sufficiently clamped in a prepared weld frame :

-  All materials are structurally aligned and clamped for effective distortion control.

-  Distortion control be within 0.5° tolerance when all mechanical restrains has been removed, and no clamps will be removed unless the workpiece has naturally cooled to ambient temperature.

-  All materials are positioned for welding in a horizontal position with the weld-pool at a maximum incline of 5° in both X-axis and Y-axis.

-  The welding frame allows for backing plates on every weld-joint, and are flush and in direct pressure contact to each joint to allow sufficient eddy current paths on all weld runs, but particularly on a root run.

-  All backing plates are of 20mm BS EN 13601:2000 Cu-ETP CW004A copper to ensure no contamination of parent material during welding fusion.

 

iv.    All materials to be welded are pre-heated :

-  The point area is pre-heated to at least 700°C as per the standard procedure for low oxygen copper : AWS 5.6-ECu UNS W60189, but specific temperatures for the certified welding procedure for the particular joint will be adhered to.

-  Pre-heating is rapid with direct heating from an oxygen induced LP-gas burner, and no mechanical contact (brushes, cloth, etc.) is made to the weld area when pre-heating has commenced to ensure no contamination of the weld surfaces.

-  Temperature cycles will never be allowed to drop below 350°C, unless procedure has ended and workpiece naturally cool to ambient temperature.

-  Temperature readings are direct, central to the weld-joint, repeated to the same spot, and with a contact type, k-type thermocouple probe. ( Fluke 80PK-27 Suregrip K-type Sensor ). Temperature display is on a multi function process calibrator/display . ( Fluke 725 )

-  No optic measurement will be done due to emissivity errors and the time such a measurement takes to settle in an acceptable sample.

Temperature recordings are done with reference to time and procedure.

 

v.    All welding of busbars are robotic controlled :

-  To ensure absolute repeatability of the welding procedure for each joint, all welding is executed with a 6-axis, welding robot.

-  Each weld-run is specifically ‘taught’ and executed with exact precision in terms of nozzle approach angle, nozzle traveling speed, filler wire speed, start/stop pausing and crater control.

 

vi.    All welding is done with Gas Metal Arc Welding (GMAW) :

-  The arc is controlled by an micro-processor controlled invertor, specifically selected for welding power control ( constant kW with reference to set current and voltage control ),

-  The filler metal is deposited with straight stringer beads using spray transfer.

-  The shielding gas is then selected by the welding procedure for the particular joint, but we have different mixtures of Argon and Helium available as prescribed by the standard procedure for low oxygen copper : AWS 5.6-ECu UNS W60189.

-  Welding conditions and specific parameters are monitored and logged with reference to time and procedure and will reflect : Welding Amps, Welding Volts, filler wire feed speed in m/min, shielding gas flow in L/min.

-  Each weld run will be documented in terms of physical properties and a profile will be drawn of each deposit and volume of deposit, shape, exact position of electrode and nozzle tilt will be reflected, as part of the weld quality management plan.

 

vii.    Post- Welding activities :

-  The workpiece will be left in the welding frame to cool down naturally to ambient temperature, and will only be released when cooled down to below 30°C.

-  The endstop blocks, will be removed by machining.

-  The joint area will be cleaned, with a copper brush, and a dyepen test with activator will be performed on all welds, and results documented, together with a photo as part of the weld quality management plan.

-  If the joint area will be installed in direct contact with another element, then the weld joint will be machined with carbide milling bits, to the parent material dimensions, to ensure a flush finish which will not be under mechanical strains caused by ‘high points’

Precision markings for precision welding (left), Automated mechanical welding robot (right).

Perfection (right).

D.    Managing the manufacture quality  :

i.    Our in-house Quality Management Plan will be followed in accordance with SABS1195-1978 section 5, and all materials and assemblies will be traceable via papertrail as well as hard, stencil stamped, identification on each item.

ii.    We accomodate inspections by the client and/or 3rd party quality management services, and the quality plan will specifically be drawn up with the specific preferences of the client.

iii.    We have a well established quality management department, with a draughtsman assigned to each project to ensure constant clarity on drawing and specification issues.

iv.    All manufacturing procedures are well documented and the ‘Methodology Statements’ are thourougly briefed and acknowledged in writing by all our staff involved with the manufacturing.

v.    Weekly ‘toolbox’ talks ensure the correct application of our equipment, as we are especially proud of our busbar assembly/manufacturing

vi.    We have an excellent busbar project quality history with blue chip clients like, Impala Platinum – Springs Refinery, as well as Anglo Platinum – Rustenburg Refinery

 

E.    Analysing the performance  :

i.    The most important aspect of busbars are the current carrying capability. In this application, the designed current densities are conservative, but the implicating factor are the number and nature of the copper welds.

ii.    To establish the performance of the busbars, it will be neccessary to do tests on the busbars when they are in service. Besides the tests required during installation which should ensure a sound installation :

- Insulation tests,

- Continuity of the individual phase connections,

- Micro-Ohm tests on all joints,

 

iii.    We offer the tests required for analysing the performance of the busbars after installation :

- Current Density Tests on all busbar laminations.

- Voltage Loss Tests on entire busbar installation.

 

F.    Performance guarentee  :

i.    We guarentee that the busbars as manufactured, with special reference to the welds, will perform within the following losses :

- Any welded area will not operate higher than 5°C above the solid material in the same ambient environment for every 5kA conducted by that individual lamination,

- Any welded area will have a loss of not higher than 0.25V rms ac above the solid material in the same ambient environment for every 5kA conducted by that individual lamination.

2.    The delivery of items as per the design drawings to the clients premises :

- Delivery includes for the insurance of goods in transit for the value of replacement.

- Delivery includes for the labor to off-load and assist with stacking in the prescribed area of storage.

- Delivery includes for the SHE requirements involved with the activity.

- Delivery does not include for the services of forklifts and/or crane to off-load.

 

References :

 

Impala Platinum Ltd – Springs Refineries


•    Design, supply and installation of 140T Busbars :  2007 Financial Year
o    Very, very stringent chemical environment,
o    Very, very high quality ensurance conditions,
o    30% of installation 11m from ground level,
o    Installation while plant in full production ( less than 8 hrs downtime )

•    Supply and installation of 40T Busbars : 2009 Financial Year
o    Very, very stringent chemical environment,
o    Very, very high quality ensurance conditions,
o    Very close liason with other contractors to ensure tight schedule.

Engineering Manager :    Mr. Joseph Roux     ( Pr. Eng Electrical & Mechanical & Metalurigal )

The product that the client specified will be meticulously made to exactly the last detail, just as the client has required, with no reservations on excellence and quality.

Samples of any Cu materials, whether segments are applicable to the particular project, or not, may be taken from our factory without prior warning, for analysis to confirm that only BS EN 13601:2000 Cu-ETP CW004A copper busbars are processed in our works.

For a more detailed account on our busbar specifications, or further information please contact Izak Nel at This e-mail address is being protected from spambots. You need JavaScript enabled to view it