Question-   School Structural Characteristics

Solution-
      1. Classroom structure & incoming power line characteristics

The school structure characteristics are shown in Table 1.

Table 1: Palabek secondary school: environment and structural characteristics for the classroom and office

Input parameter

Comment

Symbol

Value

Reference (SANS63205)

 Ground flash density (1/km2/year)

 

NG

16

Stroke density map from Viasala

Structure dimensions (m)

 

Classroom( Block A, B or E)

Office( Block C or D)

 

 

 

 

L, W, H

 

 

47.19, 7.05, 2.7

20.61, 7.05, 2.7

 

Layout diagram of Palabek secondary school

Location factor of structure (classrooms are surrounded by tall trees)

Isolated structure surrounded by higher objects

CD

0.25

Table A.1

LPS

None

PB

1

Table B.2

Equipotential bonding

None

PEB

1

Table B.7

External spatial shield

None

KS1

1

Equation (B.5)

 

Table 2: Palabek secondary school: Classroom power line characteristics

Input parameter

Comment

Symbol

Value

Reference

Length (m) a

 

LL

1000

 

Installation factor

Buried

CI

0.5

Table A.2

Line type factor

LV line

CT

1

Table A.3

Environmental factor

Rural

CE

1

Table A.4

Shield of line

Unshielded

RS

Table B.8

 

Shielding, grounding, isolation

 

None

CLD

1

 

Table B.4

CLI

1

Adjacent structure

For classroom -

For office -

None

 

LJ, WJ, HJ

 

47.19, 7.05, 2.7

20.61, 7.05, 2.7

 

Location factor of structure

None

CDJ

0.25

Table A.1

Withstand voltage of internal system (kV)

 

UW

2,5

 

 

 

Resulting parameters

KS4

0,4

Equation (B.7)

PLD

1

Table B.8

PLI

0,3

Table B.9

aAs the length Lof  the line section is unknown, L =1000 m is assumed (Clause A.4 and Clause A.5)

    1. Determining of losses

As a school is an area whereby most of the day a lot of learners and teachers are found, the only loss that will be considered for this study is the loss of human life (L1).

    1. Definition of zones

The following zones are identified as marked on the layout diagram in Appendix A:

  • Zone 1 – outside the classrooms
  • Zone 2 – inside the classrooms
  • Zone 3 – inside the offices

It is assumed that during a thunderstorm there will be no person in Zone 1 thus the risk component of this zone is negligible. A safety precaution procedure which will be discussed in the latter part of this study will ensure that there are no persons in Zone 1 during a thunderstorm. The distribution of people in the different zones is shown in Table 3 below.

Table 3: Palabek secondary school: Distribution of people in zones

Zone

Number of people

Time of presence

Zone 1

0

-

Zone 2

50

1200 hrs

Zone 3

4

1200 hrs

Total

nt= 54

-

 

The factors valid for Zone 2 and Zone 3 are shown in Table 4 and Table 5 below.

Table 4: Palabek secondary school: factors valid for Zone 2

Table 5: Palabek secondary school: factors valid for Zone 3

 

 

 

Table 4: Palabek secondary school: factors valid for Zone 2

Input parameter

Comment

Symbol

Value

Reference

Type of floor

Concrete

rt

10-2

Table C.3

Protection against shock (flash to line)

None

PTU

1

Table B.6

Protection against shock (flash to structure)

None

PTA

1

Table B.1

Probability that a flash to a the structure will cause injury to living beings by electric shock

None

PA

1

Equation (B.2)

Probability that a flash to a line will cause injury to living beings by electric shock

None

PU

1

Equation (B.8)

Probability that a flash to a line will cause physical damage

None

PV

1

Equation (B.9)

Risk of fire

Low

rf

10-3

Table C.5

Fire protection

None

rp

1

Table C.4

Internal spatial shield

None

KS2

1

Equation (B.6)

 

 

Power

Internal wiring

Unshielded

(loop conductors

in the same conduit)

KS3

0,2

Table B.5

Coordinated SPDs

None

PSPD

1

Table B.3

 

 

 

 

 L1: Loss of human life

Special hazard: none

hz

1

Table C.6

D1: due to touch and step voltage

LT

10-2

 

 

 

Table C.2

D2: due to physical damage

LF

10-1

D3: due to failure of internal systems

LO

-

 Factors  for persons in zone

nz/ nt´ tz/ 8 760 = 50 /54´ 1200/8760

 

0.12

Page 51

 

Resulting parameters

LA

1.2 x 10-5

Equation (C.1)

LU

1.2 x 10-5

Equation (C.2)

LB = LV

1.2 x 10-5

Equation (C.3)

 

Table 5: Palabek secondary school: factors valid for Zone 3

Input parameter

Comment

Symbol

Value

Reference

Type of floor

Concrete

rt

10-2

Table C.3

Protection against shock (flash to line)

None

PTU

1

Table B.6

Protection against shock (flash to structure)

None

PTA

1

Table B.1

Probability that a flash to a the structure will cause injury to living beings by electric shock

None

PA

1

Equation (B.2)

Probability that a flash to a line will cause injury to living beings by electric shock

None

PU

1

Equation (B.8)

Probability that a flash to a line will cause physical damage

None

PV

1

Equation (B.9)

Probability that a flash near a structure will cause failure of internal system

None

PM

1

Equation (B.3)

Probability that a flash to a line will cause failure of internal system

None

PW

1

Equation (B.10)

Probability that a flash near line will cause failure of internal system

None

PZ

1

Equation (B.9)

Probability that a flash to the structure will cause failure of internal system

None

PC

1

Equation (B.4)

Risk of fire

Low

rf

10-3

Table C.5

Fire protection

None

rp

1

Table C.4

Internal spatial shield

None

KS2

1

Equation (B.6)

 

 

Power

Internal wiring

Unshielded

(loop conductors

in the same conduit)

KS3

0,2

Table B.5

Coordinated SPDs

None

PSPD

1

Table B.3

 

 

 

 

 L1: Loss of human life

Special hazard: none

hz

1

Table C.6

D1: due to touch and step voltage

LT

10-2

 

 

 

Table C.2

D2: due to physical damage

LF

10-1

D3: due to failure of internal systems

LO

-

 Factors  for persons in zone

nz/ nt´ tz/ 8 760 = 50 /54´ 1200/8760

 

10-2

Page 51

 

Resulting parameters

LA

1 x 10-6

Equation (C.1)

LU

1 x 10-6

Equation (C.2)

LB = LV

1 x 10-6

Equation (C.3)

 

  1.  
  2. Calculation of collection areas

 

The collection areas are calculated for the classroom and office block as shown in Table 6 and 7 below.

Table 6: Palabek secondary school: Classroom collection areas

 

Symbol

Result

m2

Reference

Equation

Equation

Structure

AD

Block B – 978

(A.2)

AD = L x W + 2 x (3 x H) x (L + W) + π x (3 x H)2

AM

(A.7)

Not relevant

Power line

AL/P

4,00 x 104

(A.9)

AL/P= 40 x LL

AI/P

4,00 x 106

(A.11)

AI/P= 4 000 x LL

ADJ/P

978

(A.2)

ADJ/P = L x W + 2 x (3 x H) x (L + W) + π x (3 x H)2

 

Table 7: Palabek secondary school: Office collection areas

 

Symbol

Result

m2

Reference

Equation

Equation

Structure

AD

Block C - 575

(A.2)

AD = L x W + 2 x (3 x H) x (L + W) + π x (3 x H)2

AM

(A.7)

Not relevant

Power line

AL/P

4,00 x 104

(A.9)

AL/P= 40 x LL

AI/P

4,00 x 106

(A.11)

AI/P= 4 000 x LL

ADJ/P

978

(A.2)

ADJ/P = L x W + 2 x (3 x H) x (L + W) + π x (3 x H)2

 

    1. Calculation of expected annual number of events

 

Table 8 : Pabalek secondary school: Expected annual number of dangerous events for the classroom

 

Symbol

Result1/year

Reference

Equation

Equation

 

Structure

ND

Block B – 3.9´ 10–3

(A.4)

ND= NG´ AD´ CD´ 10–6

NM

(A.6)

Not relevant

 

Power Line

NL/P

64´ 10–2

(A.8)

NL/P= NG´ AL/P´ CI/P´ CE/P´ CT/P´ 10–6

NI/P

16

(A.10)

NI/P= NG´ AI/P´ CI/P´ CE/P´ CT/P´ 10–6

NDJ/P

3.9´ 10-3

(A.5)

NDJ/T= NG´ ADJ/P´ CDJ/P´ CT/P´ 10–6

 

 

Table 9: Pabalek secondary school: Expected annual number of dangerous events for the office

 

Symbol

Result1/year

Reference

Equation

Equation

 

Structure

ND

Block D – 2.3´ 10–3

(A.4)

ND= NG´ AD´ CD´ 10–6

NM

(A.6)

Not relevant

 

Power Line

NL/P

64´ 10–2

(A.8)

NL/P= NG´ AL/P´ CI/P´ CE/P´ CT/P´ 10–6

NI/P

16

(A.10)

NI/P= NG´ AI/P´ CI/P´ CE/P´ CT/P´ 10–6

NDJ/P

3.9´ 10-3

(A.5)

NDJ/T= NG´ ADJ/P´ CDJ/P´ CT/P´ 10–6

 

    1. Calculation of Risk

 

Table 10: Calculation of risk components

Type of Damage

Source of Damage

Risk Component

Z1

Z2

Z3

Structure

D1

Injury

Lightning flash to a structure

RA=ND.PA.LA

-

4.6´ 10–8

2.3´ 10–9

4.8´ 10–8

Lightning flash to an incoming line

RU=(NL+NDJ).PU.LU

-

7.7´ 10–6

6.4´ 10–7

8.3´ 10–6

D2

Physical Damage

Lightning flash to a structure

RB=ND.PB.LB

-

4.6´ 10–8

2.3´ 10–9

4.8´ 10–8

Lightning flash to an incoming line

RV=(NL+NDJ).PV.LV

-

7.7´ 10–6

6.4´ 10–7

8.3´ 10–6

Total

R1= 1.6´10–5

 

BecauseR1= 1.6 x 10–5is higher than the tolerable risk value ofRT= 10–5 a suitable lightning protection system for the school structure is necessary.

 

Our happy customers

They are fast in responding to homework questions. they have the best technical writers. Thanks for helping me with my programming doubts.

studentDyana
5  stars image

I contact to disklib for homework, they help me out, despite there was some technical issue they gone through extra mile for me and provide me good quality work in first priority. 100% recommended.

studying on laptopAsif Waheed
5  stars image

Desklib's study resources are best & unique. Their study database is easy to access and easy to use.
100 % recommended.

library and studentsMike Taylor
5  stars image