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Quality Control (Q.C) – Checks

In QC department there are three sections to check the products staring from the raw material used to produce the cable and during all various process of production till the final stage to ensure the quality of the products and they are confirming to the required specification before it shipped to customer

In Process Test Final Stage TestRaw Material

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1st Stage – Raw Material Test

•All raw materials are brought into the stores “to be tested” area and placed into the warehouse for QC to process and test according to materials book & work instruction for each material. These are then reported on and either accepted or rejected as below chart explains in detail.

2nd Stage – In Process Test

The purpose of the “In Process Checks” is to maintain production standards and ensure the compliance of product under manufacture is falling within the tolerances set out & manufacturing specification

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Wires Drawing Process

Here following parameters have to be checked during this process to ensure a quality wires are produced

1. Elongation test for 10 % of the drawn wires 2. Tensile Strength. for 10 % of the drawn wires 3. Wire Diameter for 10 % of the drawn wires 4. Ovality (roundness) for 10 % of the drawn

wires

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Stranding Process

Here the tests carried out are to check both the actual cross section area of particular size as specified by standard & customer requirements through.

1. Resistance measurement 2. Weight measuring: One meter sample of the stranded conductor

shall be taken from the end of every drum & weighing for cross check purpose only.

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Conductor (CU – AL )

Insulation (PVC – XLPE )

Metal Sheath ( Lead Alloy)

Inner Covering (PVC – XLPE)

Armoring

Outer Sheath (PVC – PE)

Insulation

Here a number of tests are carried out to measure the compliance of a conductor’s insulation,

(1) Insulation thickness(2) Spark Test(3) Colour of Insulation(4) Hot Set test for XLPE insulation

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Conductor (CU – AL )

Insulation Tipple layer (XLPE )

Outer Sheath (PVC – PE)

Inner Covering (PVC – XLPE)

Copper Screen

Armouring

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Medium Voltage (MV) & High Voltage (HV) Insulation (1) Insulation Thickness (2) Hot Set test (3) Measuring the eccentricity of the insulation (4) Measuring the Strippability of the insulation screen (for MV cables only) (2.5) check the transparent of the insulation (not required by the standard)

Here a number of tests are carried out to measure the compliance of a conductor’s insulation,

Insulation

Cu Tape

Screened Cable

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there are two types of screening(1) Copper Tape – thickness of tape and the % overlap of the tape after being wound onto the cable.(2) Copper Wire – actual number of wires and the diameter of each copper strand

Screening

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Assembling

here are again a number of tests carried out to measure the following

1) Overall physical diameter of assembled cable 2) Assembling Lay length of the cores 3) Filler (Polypropylene) – area of the filler

Inner Sheath

This is to measure the physical dimensions of a cut sample taken from a manufactured cable, prior to final acceptance.1. The thickness of the inner sheath

Armouring

This deals with the physical (mechanical) protection of the cables, this is done in three different methods. Here the physical properties of the armouring are tested.1. Steel Wire – actual number of strands of the wires armour and wires

diameter2. Steel Tape – the physical thickness of the tape and % overlap of tape3. Aluminium Wire – actual number of strands of the wire armour and diameter

of wire

Final Sheathing

Here the physical properties are measured to check compliance1. Thickness of outer sheath2. Cable marking (Embossing) or printing3. Spark test (e.g. for every 1mm thickness, this relates to a 6kV

electrical charge)4. Colour of outer sheath5. Length marking – stamped physically onto every 1 meter of length

sequentially

*Hot Set test

This is a test comprising of the following procedure, to test the cross linkable (or curing) properties of the XLPE insulation,

1. A sample is cut from cable under test2. The insulation is then stripped from the cable (XLP part)3. Shaved down into a set thickness (i.e. 0.8 – 1.7 mm thickness)

4. A “dumbbell” sample is stamped out for further testing.5. Then a standard measured distance of 20 mm is marked off6. When the total surface area is calculated and weight of 20N/cm2 is selected7. Then weighted load is attached to the sample and then placed in an oven at 200’C for fifteen (15) minutes8. Then the elongation (stretched) is measured and the elongation percentage calculated a maximum of 175% is the maximum is allowed.

Note: For easy & fast procedures of performing the hot set test, loads for all expecting thickness were calculated and prepared as weights pieces & kept ready for using for this test as follows:

9.807 Newton = 1000 g 1.000 Newton = 101.98 g 0.640 Newton = 65.26 g

CALCULATION OF LOAD FOR DUMBBELL TEST PIECES

Specified mechanical stress = 20 N/cm² according to IEC 60811-2-1 clause 9 Width of the specimen = 4.0

Load (Totally) (GR)

Actual Mechanical Stress (Newton)

Area (cm²)

Thickness (mm)

Stress x 101.98 Area x 20 Thick. x Width Given65.27 0.64 0.032 0.80

69.35 0.68 0.034 0.85

73.43 0.72 0.036 0.90

77.51 0.76 0.038 0.95

81.59 0.80 0.040 1.00

85.67 0.84 0.042 1.05

89.75 0.88 0.044 1.10

93.83 0.92 0.046 1.15

97.91 0.96 0.048 1.20

101.99 1.00 0.050 1.25

106.07 1.04 0.052 1.30

110.15 1.08 0.054 1.35

114.23 1.12 0.056 1.40

118.31 1.16 0.058 1.45

122.39 1.20 0.060 1.50

126.47 1.24 0.062 1.55

130.54 1.28 0.064 1.60

134.62 1.32 0.066 1.65

138.70 1.36 0.068 1.70

Size of Core (mm²)

Outer Dia. of Piece (mm)

(D)

Thick. of Insulation

(mm)

Area of Cross Section (mm²)

Area (cm²) (A) Actual Mech. Stress (N)

Total Load

(g)

1.5 2.96 0.70 4.97 0.0497 0.994 101.36

2.5 3.41 0.70 5.96 0.0596 1.192 121.55

4.0 3.95 0.70 7.14 0.0714 1.428 145.70

6.0 4.52 0.70 8.396 0.0840 1.68 171.30

Table # 2

CALCULATION OF LOAD FOR TUBULAR TEST PIECES

VOLTAGE TESTPARTIAL DISCHARGE (FOR MV/HV CABLES) CONDUCTOR RESISTANCE TAN δ MEASUREMENT (FOR HV CABLES

MADE IN EGYPT

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3rd Stage – Final test

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)A (High Voltage Test 3500Volts (3.5kV) for 5 minutes A voltage of 3500 volts is passed between a single conductor and the neutral (or earth), for a period of 5 minutes respectively. A voltage of 6.2kV is also passed between the phases to test the insulation between the different phases respectively.

Low Voltage Cables

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If this process of testing the individual core are successful passed and there are no indication of any breakdown then the cable proceed to the next test, which is

)B (Measuring the Conductors Resistance:The conductor resistance of each cutting length on drum shall be measured to verify the length of the cable as well as

1. HV test 3.5Uo voltage test is applied between the conductor & metallic screen of each core for 5 minutes

2. Conductor resistance measurement (same as explained in LV cables)3. Partial Discharge Test (PD test)

)B (Medium Voltage Cables

Partial Discharge test

The partial discharge phenomenon is known as a partial breakdown of insulation. There are three type of PD which are:1. Internal PD2. Voids PD3. Surface PD

The partial discharge is leakage charges from the conductor to the earth through weak point in the insulation such as Voids, Contaminations in the

insulation, cavities in insulation or surface damage .The purpose the PD test is to test if the minutist particles or voids are present inside the XLPE insulation. This process is to measure the leakage of the charge (Q) from the conductor to the metallic screen, through these weak points. This test is measured in Pico-Column; the international standard is

anything ≤10 pC (10-12 Columns)

Conductor Insulation Insulation’s Screen

Prepared cable end length

C=

dtdQ

Q = Charge t = time

For testing MV or HV cables electrically, cable terminals must be prepared as shown in the above figure.

U is referred to any one of the following terms: 1 .Line Voltage

2 .Line to Line Voltage 3 .Phase to Phase Voltage

U0 is referred to any one of the following terms:

1. Phase Voltage2. Phase to neutral Voltage3. Line to neutral Voltage

Voltage test for MV cables is 3.5 x U0, of the subject cables rated voltage

For example an 11kV cable, this means that U of this cable is 11kV, therefore the U0 for this cable is :

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11kV =6.35kV

Thus the test voltage is 3.5x 6.35kV = 22kV test voltage rating to be applied for 5 minutes

S U M M A R YQUALITY CONTROL CHECKQUALITY CONTROL CHECK

PointPoint

IN-PROCESS PRODUCTIN-PROCESS PRODUCTCOPPER & ALUMINIUM WIRE DRAWINGCOPPER & ALUMINIUM WIRE DRAWING CONDUCTOR STRANDINGCONDUCTOR STRANDING INSULATION PROCESSINSULATION PROCESSELECTRICAL SCREENELECTRICAL SCREEN LAYING UP (ASSEMBLING)LAYING UP (ASSEMBLING)FILLINGFILLINGARMOURINGARMOURING OUTER SHEATHOUTER SHEATH

IN-PROCESS PRODUCT TESTIN-PROCESS PRODUCT TESTSURFACE ( VISUAL )SURFACE ( VISUAL ) DIMENSIONDIMENSION TENSILE STRENGTHTENSILE STRENGTH ELONGATIONELONGATION SPARK TEST ON INSULATION LINESPARK TEST ON INSULATION LINE HOT SET FOR XLPE INSULATIONHOT SET FOR XLPE INSULATION CABLE MARKINGCABLE MARKING PARTIAL DISCHARGE PARTIAL DISCHARGE

))For screened Cores of MV / HV CableFor screened Cores of MV / HV Cable

Function/ Function/ DeptDept.. ProcessProcess ProcedureProcedure

Tech. Dept./ Prod. Planning Dept.

According to spec. identified through sales (contract review).

QC Engineer Issue plan to QC supervisor/ Inspector.

QC Supervisor For each manufacturing stage (as per inspection & test plan).

Production Supervisor

QC Inspector Attach tag to indicate status.

QC supervisor/ Inspector

- Sample frequency as specified in In-Process Inspection.- Continuous feedback about the trend of the result to the operator.

QC Supervisor/ Inspector

- Identify rejected products as per nonconformity procedure.- Identify the accepted product.

QC Engineer

Quality Trends to be reviewed and published in MRM and action plan to be established to reduce nonconformities.

IN-PROCESS INSPECTION & TESTINGIN-PROCESS INSPECTION & TESTING

CABLE FINAL TESTINGCABLE FINAL TESTING

11 . .ROUTINE TESTROUTINE TEST

Tests made on every finished length of cable or during manufacture to ensure compliance with construction requirements

and demonstrate the integrity of the cable .

• Sampling criteria : 100 % of finished product

Tests made on samples of cable to represent production batches and provide a periodic check on manufacturing consistency.

• Sampling criteria: 10% of total quantity order as per IEC 60502.

22 . .SAMPLE TESTSAMPLE TEST

33 . .TYPE TESTTYPE TESTTests made during the development of a new grade of cable design to establish performance characteristics.• Sampling criteria: 1 sample of new design product.

FINISHED PRODUCT ROUTNE TEST FINISHED PRODUCT ROUTNE TEST (100% TEST)(100% TEST)

VISUAL INSPECTION OF CABLES DRUMSVISUAL INSPECTION OF CABLES DRUMSCONDUCTOR RESISTANCE CONDUCTOR RESISTANCE VOLTAGE TESTVOLTAGE TEST PARTIAL DISCHARGE FOR MV & HV PARTIAL DISCHARGE FOR MV & HV CABLESCABLESINSULATION RESISTANCE (IF REQUIRED)INSULATION RESISTANCE (IF REQUIRED)TAN δ FOR HV CABLES (10 % OF CUTTING TAN δ FOR HV CABLES (10 % OF CUTTING LENGTH)LENGTH)

Function/ Function/ Dept.Dept. ProcessProcess ProcedureProcedure

QC Inspector

From production Department

Check cable marking/ embossing

According to applicable Test instructions

According to work order no.

QC Lab Non- electrical tests.

QC Engineer Stamp "Passed QC"

QC Manager

To be reviewed and published in MRM

FINAL INSPECTION & TESTINGFINAL INSPECTION & TESTING

QUALITY CONTROL DEPARTMENT

QUALITY OBJECTIVEES (1)Date of setting: 01-03-2006Date of implementation: 9/03/2006

1 (CONDUCTOR RESISTANCE:

A. COPPER CONDUCTORS:•From 1.5 mm² to 6 mm² -1.5 % + 0.0% from the maximum specified value•From 10 mm² to 35 mm² -1.0 % + 0.0% from the maximum specified value •From 50 mm² to 630 mm² -0.8 % + 0.0% from the maximum

specified value

B. ALUMINUM CONDUCTORS:•From 10 mm² to 35.0 mm² -1.50% + 0.0% from the

maximum specified value•From 50 mm² to 630 mm² -1.00% + 0.0% from the

maximum specified value

2 (INSULATION:

A) XLPE Insulation:•From 0.0 mm to 1.0 mm, maximum allowed +8.0% from the

average required•From 1.1 mm to 1.5 mm, maximum allowed +6.0% from the average required•From 1.6 mm to 2.5 mm, maximum allowed +5.0% from the average required•More than 2.50 mm, maximum allowed +4.0% from the average required

B) NYA & Flex Insulation: • From 1.5 to 16 MM² conductor sizes, maximum insulation thickness allowed is +6% from the average required• From 25 to 70 MM² conductor sizes, maximum insulation thickness allowed is +5% from the average required

3 (INNER SHEATHOnly the minimum value has to be achieved & the maximum value shall be 95% of the nominal value .

Unless otherwise for some special specification or agreement between the El Sewedy & customer to achieve both value (average & minimum), so in this case the maximum allowed value should be +6 % from the average required

4 (OUTER SHEATH

A) Sheath over Armouring or Direct sheath:

Only the minimum value is required to be achieved & the maximum value shall be 95% of the nominal one.

B. Sheath over smooth surface or sheath for flex cables:

The maximum allowed value should be +8.0 % from the average required

5 (CCV LINE (MV & HV Cables)

Conductor screen: The maximum thickness allowed +10 % from the average required Insulation screen: The maximum thickness allowed +3 % from the average required Insulation: The maximum thickness allowed +4 % from the average required

InsulationInsulation AssemblyAssembly Inner sheathingInner sheathing

StrandingStranding

DrawingDrawing

Lead SheathingLead Sheathing ArmouringArmouring

Outer SheathingOuter Sheathing

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- CABLE COST 90 % MATERIAL COST 10% PRODUCTION COST - MATERIAL COST MATERIAL PRICE MATERIAL CONSUMPTION

- MATERIAL PRICE

REDUCE CABLE COST

How you can reduce the Material Price?

Look always for additional supplier.Replace the actual material with a cheaper solution

MATERIAL CONSUMPTION

IN PRODUCTION IN DESIGN DEPARTMENT

IN PRODUCTION:

MATERIAL OVERUSAGE

* Look for the tolerance –range for each production step, also for different machine. (Quality Department). If the tolerance-range is too high, look for the reason (bad material, old machine, bad measurement-equipment…and “make it better” * Reduce set-up-length * It will be helpful, that all necessary process data are written down for the personal at the machine. * Reduce scrap.

IN DESIGN DEPARTMENT: * Design department is one of the important departments to influence the cable cost. *The design engineer must create cheapest cable design solution in accordance with the customer specification. * Look for “gaps” in the specification, it means, what is not required in the specification.

During our 2 weeks discussion with many colleagues from Production, quality, technical, planning and financial,

We found many points you can change it.

80% of your orders are with 8 Types: The last 2 days we have made a cable re-design with the designer colleagues in accordance the new points, Also 2 offers for 220 kV-cables.

1) Reduce nominal thickness for inner and outer semiconductor layer. 2) Change the copper tape screening from 1 tape to 2 tapes. 3)Reduce the filler material in 3-core-cable with round conductor. 4)Fix the assembled cores with a tape as open helix. 5)In many specifications there is no average thickness required for bedding, separation sheath. Therefore reduce the thickness.

6) Indicate in design sheet the different value: Nominal, Minimum, Average & Practical Value. 7) Copper wire screen in mostly cheaper than copper tape screen. 8) Produce conductor for XLPE cable =10 kV only with dies. 9) Remove all fillers in 1 kV sector conductor – cables.10) Reduce master batch colour in 1 kV cable with skin insulation 11)Manufacturing insulation for 1kV cable only in tube extrusion.12) Try to use for 1kV cable as bedding a tape (instead extruded bedding).13) Flat wire armouring is less in cost than round wire armouring. Check to improve your armouring machine for flat wire.14) Check your PVC- compound to increase the filler

It is really a great pleasure for me to work together with the very friendly and well experience people in EL SEWEDY CABLES

THANKS

Eng’r. Mohsen Al TandiQuality Control ManagerArab Cables Company