Distribution Staking and Line Design Course

REA Tanzania

Welcome

During my 15 years of overseas experience I have designed and built more than 1,000 kilometers

of distribution line in 12 countries.

That is a lot of walking

Welcome

My name is Md Maruf Hasan

I will be your instructor for this course.

Welcome

Assisting me is Osman Hussein

&

Hussein Shamdas

Rules of the Course

• Attendance is taken daily

• No cell phone use - turn them off

• Phones may be used during breaks

• There will be quizzes/examinations

• There will be field exercises

Quizzes will be graded

• Points are given for correct answers

• Partial correct answers are awarded points

• Incorrect answers receive negative points (do not guess)

• Quiz points for the course are accumulative

What you will need

• Wear comfortable work shoes

• Bring a hat

• Bring a memory stick if you want copies of material

Pole Ground Line

Pole Length

m

Pole Class

Rated Breaking Strength*-

Nt

Ground line location**

m

9 Medium 6,300 1.5

11 Medium 7,700 1.8

12 Medium 8,000 2

13 Medium 10,000 2

* Load at 0.6m below pole top that breaks pole at the ground line**Distance from pole butt in meters.

Conductor Ruling Span

Ruling and Limit Spans for 33kV lines

Conductor Code Name

Ruling Spanm

Limit spansm

Hare 90 105Hare 50* 71Rabbit 120 145Rabbit 50* 71Gopher 120 145Gopher 50* 71Shrike 175 210Shrike 50* 71Periwinkle 50 71

Slide 10/82

* When used with underbuild LV line or in areas where LV underbuild may be anticipated in the near future.

Conductor Uplift

Conductor

ACSR

(Aluminum Conductor Steel Reinforced)

APPLICATIONS

Used as bare overhead transmission cable and as primary and secondarydistribution cable. ACSR offers optimal strength for line design. Variable steelcore stranding enables desired strength to be achieved without sacrificingampacity.

Conductor

AAAC

(All Aluminum Alloy Conductor)

APPLICATIONS

Used as bare overhead conductor for primary and secondary distribution.

Designed utilizing a high-strength aluminum alloy to achieve a high strength-to-weight ratio; affords better sag characteristics.

Aluminum alloy gives AAAC-6201 higher resistance to corrosion than ACSR.

LV Cables

Triplex

Conductor

Automatic splice

Conventional Meter

Meter

Line Material

These are galvanized washers

- Curved Square Washer

- Square Washer

- Round Washer

Line Material

Anchor Shackle

Line Material

Eyenut

Line Material

Curved Lock Nut

Line Material

Eyebolt (Oval Eyebolt)

Line Material

Machine Bolt

Line Material

Preformed Deadend

Line Material

Distribution Cutout

Line Material

Lightning/Surge Arrester

IntroductionPart I - Line Design

This course deals with Line Design in the field through the use of a methodology called ‘Staking’

What is Staking?

The process of staking takes the task of line design from the office to the field. Using tables, illustrations and guidelines the staking engineer is able to construct a safe, reliable, and economical distribution line.

Why is it called Staking?

Stakes, usually made of wood, are used to make the location of the structures.

Staking

The staking of a distribution line consists of the selection of the various physical components, including conductors, poles, pole-top assemblies, guys, anchors, etc. that comprise distribution structures.

Staking

Staking though, is not simply the placement of wooden stakes in the ground.

Staking is the a complete engineering evaluation of the choice of each structure and its location prior to driving the first stake

Staking

This is a Stake

Construction Unit

A construction or assembly unit is a specific component that is installed as part of the building block to construct an entire distribution structure. Each assembly drawing is made of materials and has stated limitations of design

Construction Drawing

• Dimensions of the components of the assembly.

• Design limits and recommendations.

• Bill of materials required for construction.

Construction Drawing• C1 0° - 5°• C2 5° - 30° Rabbit 50 mm2

• C2 5° - 15° Dog 100 mm2

• C2 5° - 10° Wolf 150 mm2

• C3 25° - 60°• C4/2C7 60° - 150°• C7 Horizontal Deadend• C8 Double Deadend

Construction Drawing

This is a 3Ø assembly. It is designed to support conductor from 0° to 5°. It is designated as C1.

The pole is not part of the unit

Construction as Built

Construction Drawing

This is a 3Ø vertical assembly. It is designed to support conductor from 30° to 60°. It is designated as C3.

Construction Drawing

This is a guy (stay) assembly. It is designed to support a pole at angles or deadends. It is designated as E1.

Construction Drawing

This is an anchor assembly. It is designed to work in conjunction with a guy (stay) at angles or deadends. It is designated as F1.

Construction Safety

• Adequate clearance & separation between conductors.

• Clearances to meet TANESCO requirements for jumpers, and climbing and working space.

• Clearances to permit safe hot line work.

Construction Safety

• High impulse strength for the outer phases through the use of wood crossarms.

• Minimal radio and TV interference by providing generous separation of phase associated hardware from grounded conductors and/or hardware.

Staking Sheet

• A staking sheet should be prepared to fully describe the construction for the proposed line.

• Typically, a staking sheet will include as a minimum the following data:

Staking Sheet

• Name of job

• Name of staking technician

• Date when staked

• Sheet number

• GPS points

• Construction Assemblies

• Span lengths

• Conductor size & type

• Line angle

Staking Sheet

Desingned by:

Substaton: Substation Feeder:

Date Ground

Map grid No(s) Lead Cap

Sheet No. of M. kVA

Column Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 18 19 20SKETCH OF WORK

Qty Qty Qty.

PROJECT: AREA Kilombero/Mbozi STAKING SHEETBuilt by:

GPS. No.

POLES PRIMARY SECONDARY GUYS ANCHOR Xfmr.Removal

UnitObservations

and notesSize/ Class

Angle Back Span

UnitCond Size

Back Span

Unit UnitCond Size

Unit Unit Qty. Unit Qty.

LCDP in Tanzania,

Misc Units

Unit Qty

Page Totals

Removal Units

Item

Condcutor

21

Item

New Units

New Units

Item

Poles

Staking SheetPole Numbering

Staking SheetPole Numbering

 Example: EC-EH-22-5-Bad

EC EH 22 5 B a d 

Substation Feeder Pole no. Tap LV lv lv

 Substation – A two-letter designation is assigned to all 11 kV and 33 kV substations.  Feeder – A two-letter designation is assigned to all 11 kV and 33 kV substation feeders. 

Staking SheetPole Numbering

Example: EC-EH-22-5-Bad

EC EH 22 5 B a d  Substation Feeder Pole no. Tap LV lv lv  Pole no. – The pole no. is the correlative number of the pole of a particular feeder . If two poles exist at the same location such as a transformer or equipment location where the two poles are physically connected by a platform, then a decimal point and number will be added i.e. EC-EH-22-2.1 and EC-EH-22-2.2. If a pole is inserted at a later date then a decimal point and number will also be added.

Tap (optional) – If there is a primary line tap from a feeder, then a number will be used after the corresponding Pole no. Otherwise the space will be blank. If there is a tap from a tap, again a number designation will be assigned after the corresponding Tap pole number designation.

Staking SheetPole Numbering 

Example: EC-EH-22-5-Bad EC EH 22 5 B a d

  Substation Feeder Pole no. Tap LV lv lv

 LV – An Upper-case letter will be used to designate the secondary feeds from a transformer. Facing north and moving clockwise, the first secondary LV feed will be ‘A’, the next in rotation will be ‘B’ and so forth. lv – A lower-case letter will be used to designate the pole position along the feed. Aa would be the first secondary pole on the A feed. Bb would be the second pole along the B feed, and so forth. lv - Additional lower-case letter(s) will be used to designate a secondary tap or derivation from a secondary feed. Bad indicates that from the third pole of secondary feed B there are four additional poles to arrive at Bad.

 

Staking SheetLine Sketch

• Route of the line to built

• Poles

• Guys and Anchors

• Transformers

• Taps

• Sectionalizing Devices

• Secondary Line

• Open Points

Staking SheetLine Sketch

These symbols are used when preparing the sketch on the staking sheet.

Staking Sheet

Staking Sheet

Staking Sheet

Staking Sheet to Material List

Use interactive UniCalc

Staking Crew Equipment

• Hammer, 1 kg. • Spray Paint

• Nails, 6” MS • Back Pack

• Nails, 3” Concrete • Theodolite & Tripod

• Bottle Caps • Tape 10 m & 100 m

• Pencils & Markers • Staking Template

• Traffic Cones • Staking Form Holder

• Safety Vests • Measuring Stick 10 m

• Hats • Hand Level

• Machete • Water Thermos