1

ac electrification with dc clearancesRichard Stainton

Dr Paul Naylor

2

UK Railway

3

Typical Electrification Cost Breakdown

Overhead Contact System

Civils (Bridges, Tunnels,

Stations, etc.)

Other (Power, Signalling,

etc.)

4

Cardiff Intersection Bridge

Flashover Opportunities

1 Flashover from

Underbridge Arm to Bridge

270 mm

2 Flashover from Contact

Wire to Bridge

270 mm

3 Flashover from OLE to

Train Roof

270 mm –

150 mm

4 Flashover from Uplifted

Underbridge Arm to Bridge

150 mm

5 Flashover from Uplifted

Contact Wire to Bridge

150 mm

6 Flashover from Depressed

Pantograph to Pan Well

170 mm

7 Flashover from Pantograph

to Bridge

150 mm

6

Hazard Analysis

Energised OCL

Clearance

Compromised

by Debris

Clearance

Compromised

by Pantograph

Uplift

Damage to

OCL

Damage to

BridgeVoltage

Transient

Flash-

over

7

Transient Traces

7-May-19 7

Voltage

Transient

8

Transient TracesVoltage

Transient

9

Impulse protection level:

U10kA - 8/20µs = 75 kV

Voltage

TransientSurge Arrestor

10

Hazard Analysis

Energised OCL

close

Clearance

Compromised

by Debris

Clearance

Compromised

by Pantograph

Uplift

Damage to

OCL

Damage to

BridgeVoltage

Transient

Flash-

over

11

PTFE Contact Wire Cover (Kago)Clearance

Compromised

by Pantograph

Uplift

12

Polyurea Coating (GLS100R)Clearance

Compromised

by Pantograph

Uplift

13

Electrical Stress Graded Bridge ArmClearance

Compromised

by Pantograph

Uplift

14

Insulated Bridge Arm & Wire CoverClearance

Compromised

by Pantograph

Uplift

15

Clearance

Compromised

by Pantograph

Uplift

16

Clearance

Compromised

by Pantograph

Uplift

17

Clearance

Compromised

by Pantograph

Uplift

18

Insulated Bridge Arm ResultsClearance

Compromised

by Pantograph

Uplift

+ - + - + - + - + - + - + - + -

Contact Wire Only

Surge Arrestor ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓

Surge Arrester and contact

wire cover✓✓✓ ✓✓✓ ✓✓✓

Surge Arrester, contact wire

cover and insulated coating✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Contact Wire Only

Surge Arrestor ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Surge Arrester and contact

wire cover✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓

Surge Arrester, contact wire

cover and insulated coating✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓ ✓✓

Key

= Flashover

✓ = Pass

Mitigation70 mm 60 mm

Clearance

30 mm 20 mm 10 mm 0 mm50 mm 40 mm

Failed with both impulse

polarities

Passed with one impulse

polarity

Passed with both

impulse polarities

Dry

Wet

19

Bridge Arm Uplift MeasurementsLow Speed (<100 kmph)

Clearance

Compromised

by Pantograph

Uplift

20

Hazard Analysis

Energised OCL

close

Clearance

Compromised

by Debris

Clearance

Compromised

by Pantograph

Uplift

Damage to

OCL

Damage to

BridgeVoltage

Transient

Flash-

over

21

Hazard Analysis

Energised OCL

lower than

4165 mm

Clearance

Compromised

Pan – Pan Well

Clearance

Compromised

OCL - Staff

Damage to

Plant

Damage to

Train

Clearance

Compromised

OCL - Train

Roof

Flash-

over

Electric Shock

to Staff

Damage to

OCL

22

Clearance

Compromised

OCL - Train

Roof

W6a plate in environmental chamber

23

W6a flashover without surge arrestor

Clearance

Compromised

OCL - Train

Roof

24

W6a flashover - with surge arrestorClearance

Compromised

OCL - Train

Roof

25

100mm aerial flashover –without surge arrestor

Clearance

Compromised

OCL - Train

Roof

26

100 mm aerial flashover –with surge arrestor

Clearance

Compromised

OCL - Train

Roof

27

Contact Wire to Train Roof -with surge arrestor

Clearance

Compromised

OCL - Train

Roof

+ - + - + - + - + - + - + - + -

Shaped plate for W6a ✓✓✓ ✓✓ ✓✓✓ ✓

Shaped plate for W10 ✓✓✓ ✓✓ ✓✓✓ ✓

Shaped plate for W12 ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓

Shaped plate with simulated

aerial✓✓✓ ✓✓✓ ✓✓ ✓✓

Shaped plate for W6a ✓✓✓ ✓✓✓ ✓✓✓ ✓✓

Shaped plate for W10 ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓

Shaped plate for W12 ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Shaped plate with simulated

aerial✓✓✓ ✓✓ ✓✓✓ ✓✓ ✓✓

Key

= Flashover

✓ = Pass

Clearance

Test with Surge Arrester70 mm 60 mm 50 mm 40 mm 30 mm 20 mm 10 mm 0 mm

Failed with both impulse

polarities

Passed with both

impulse polarities

Passed with one impulse

polarity

Dry

Wet

28

Hazard Analysis

Energised OCL

lower than

4165 mm

Clearance

Compromised

Pan – Pan Well

Clearance

Compromised

OCL - Staff

Damage to

Plant

Damage to

Train

Clearance

Compromised

OCL - Train

Roof

Flash-

over

Electric Shock

to Staff

Damage to

OCL

29

Pantograph Horn Testing -

without surge arrestor

Clearance

Compromised

Pan – Pan Well

30

Pantograph Horn Testing -

with surge arrestor

Clearance

Compromised

Pan – Pan Well

31

Pantograph Horn to Train Roof with surge arrestor

Clearance

Compromised

Pan – Pan Well

+ - + - + - + - + - + - + - + - + -

Brecknell Willis HS-A Pan. Horn ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2)✓✓✓ ✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2) Low Stress✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Falverley CX Insulated Pan.

Horn✓✓✓ ✓✓✓

Brecknell Willis HS-A Pan. Horn ✓✓✓ ✓✓✓ ✓✓✓ ✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2)✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2) Low Stress✓✓✓ ✓✓✓ ✓✓✓ ✓✓ ✓✓✓ ✓

Falverley CX Insulated Pan.

Horn✓✓✓ ✓✓✓

Key

= Flashover

✓ = Pass

Clearance

Test with Surge Arrester80 mm 70 mm 60 mm 50 mm 40 mm 30 mm 20 mm 10 mm 0 mm

Dry

Wet

Failed with both impulse

polarities

Passed with one impulse

polarity

Passed with both

impulse polarities

32

Pantograph Horn to Infrastructure

without surge arrestor

Clearance

Compromised

Pan – Bridge

33

Pantograph Horn to Infrastructure

with surge arrestor

Clearance

Compromised

Pan – Bridge

34

Pantograph Horn to Infrastructure Clearance

Compromised

Pan – Bridge

+ - + - + - + - + - + - + - + - + -

Brecknell Willis HS-A Pan. Horn ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2)✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2) Low Stress✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Falverley CX Insulated Pan.

Horn✓✓✓ ✓✓✓

Brecknell Willis HS-A Pan. Horn ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2)✓✓✓ ✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2) Low Stress✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Falverley CX Insulated Pan.

Horn✓✓✓ ✓✓✓

Key

= Flashover

✓ = Pass

Dry

Wet

80 mm

Clearance

Failed with both impulse

polarities

Passed with one impulse

polarity

Passed with both

impulse polarities

Test with Surge Arrester70 mm 60 mm 50 mm 40 mm 30 mm 20 mm 10 mm 0 mm

35

Electrical Clearances Clearance

Compromised

Pan – Object

36

Survey of Handheld Objects at StationsClearance

Compromised

Pan – Object

37

Pantograph Horn to

Handheld Object without

surge arrestor

Clearance

Compromised

Pan – Object

38

Pantograph Horn to

Handheld Object

with surge arrestor

Clearance

Compromised

Pan – Object

39

Pantograph Horn to Handheld Object with surge arrestor

+ - + - + - + - + - + - + - + - + -

Brecknell Willis HS-A Pan. Horn ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2)✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓

Brecknell Willis HS-P Pan. Horn

(Mk2) Low Stress✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Falverley CX Insulated Pan.

Horn✓✓✓ ✓✓✓

Brecknell Willis HS-A Pan. Horn ✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓ ✓✓ ✓✓✓ ✓

Brecknell Willis HS-P Pan. Horn

(Mk2)✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Brecknell Willis HS-P Pan. Horn

(Mk2) Low Stress✓✓✓ ✓✓✓ ✓✓✓ ✓✓✓

Falverley CX Insulated Pan.

Horn✓✓✓ ✓✓✓

Key

= Flashover

✓ = Pass

Clearance

Test with Surge Arrester80 mm 70 mm 60 mm 50 mm 40 mm 30 mm 20 mm 10 mm 0 mm

Dry

Wet

Failed with both impulse

polarities

Passed with one impulse

polarity

Passed with both

impulse polarities

Clearance

Compromised

Pan – Object

40

25 kV ac

EN 50119

EN 15273:1

200 kV ac

EN 50124

Without

Mitigation

200 kV ac

EN 50124

With Mitigation

750 V dc

EN 50119

EN 15273:1

1 - Flashover from

Underbridge Arm to Bridge

270 mm 200 kV

(370 mm)

20 mm 100 mm

2 - Flashover from Contact

Wire to Bridge

270 mm 200 kV

(370 mm)

70 mm 100 mm

3 - Flashover from OLE to

Train Roof

270 mm –

150 mm

200 kV

(370 mm)

70 mm 100 mm –

50 mm

4 - Flashover from Uplifted

Underbridge Arm to Bridge

150 mm 200 kV

(370 mm)

20 mm +1.5

S0

50 mm

5 - Flashover from Uplifted

Contact Wire to Bridge

150 mm 200 kV

(370 mm)

70 mm 50 mm

6 - Flashover from Pan. to

Pantograph Well

170 mm 200 kV

(370 mm)

80 mm 100 mm

7 - Flashover from

Pantograph to Bridge

170 mm 200 kV

(370 mm)

80 mm 50 mm

8 – Flashover from Panto-

graph to Handheld Object

- 200 kV

(600 mm)

112 mm -

41

ac electrification with dc clearances

41

Improved electrical

performance

Less disruption Less expensive

Faster to install