ECL Power System Standards
01020‐DPR‐3304
MV Switchgear – SF6
Ergo Consulting
01020 / 1020‐DPR‐3304 / Revision 1 / 16‐Jul‐2022
Document history and status
Revision
Date
Author
Reviewed by
1
16‐Jul‐22
Chris Turney
Chris Turney
Revision details
Revision
Details
Approved by
Status
`
Table of Contents
1.
MV/HV switchgear insulation: greenhouse gases – is SF6 a problem? ............................................. 1
1.1
Introduction ....................................................................................................................................... 1
1.2
Concrete ............................................................................................................................................. 1
1.3
Conclusion .......................................................................................................................................... 2
2.
Appendices ...........................................................................................................................................i
Appendix 1
Switchroom Sizes ...................................................................................................................... iv
Index of Tables
Table 1 GWP (kg) .......................................................................................................................................... 1
ECL Power System Standards / SF6
16‐Jul‐22
01020‐DPR‐3304 ‐ Revision 1
Page | iii
1. MV/HV switchgear insulation: greenhouse gases – is SF6 a problem?
1.1 Introduction
There is a move to limit the amount of SF6 used in switchgear because of its large Global Warming
Potential (GWP). One kilogram of SF6 has the same GWP100 (GWP for 100 years) as 23,500 kg of CO2. To
put it in perspective 100 g of SF6 is the same as driving a Toyota Corolla 16,000 km
Apart from the manufacture of the switchgear which requires resources and energy regardless of its
insulation, leakage of SF6 has the most GWP. For the switchgear to be sealed for life (which may be
between 30 and 50 years) the leakage rate must be minimal. Standards require that it must be less than
0.1% leakage per year. In practice, manufacturers achieve 0.01%. For a typical 11 panel switchboard, this
is 4 g of SF6 per year, equal to 94 kg of CO2 or 650 km in a Toyota Corolla.
SF6 is bad for the environment but while other products are in development nothing replaces it for:



Compactness
Safety
Reliability
While there are some choices of insulation at lower voltages (11 kV and 33 kV) there is significantly less
choice at higher voltages where AIS requires large air‐gaps for insulation.
Like all harmful products, SF6 this must be monitored for leakage and regularly audited. At end‐of‐life,
SF6 is extracted from the switchgear and recycled.
1.2 Concrete
When considering SF6 it is important to recognise the contribution that concrete makes to global
warming.
Wikipedia
The cement industry is one of the two largest producers of carbon dioxide (CO2), creating up to
8% of worldwide man‐made emissions of this gas, of which 50% is from the chemical process and
40% from burning fuel. The CO2 produced for the manufacture of structural concrete (using
~14% cement) is estimated at 410 kg/m3
At 33 kV, the size of a switchroom (11 panel) using Air Insulated Switchgear (AIS) is approximately 90 m2
while a Gas Insulated Switchgear (GIS) switchroom is approximately 30 m2. This results in the following
lifetime GWP:
Table 1 GWP (kg)
Lifetime (30 Years)
GIS
AIS
Unit
Switchgear leakage
2,831
0
kg (CO2 Eq.)
Concrete*
13,530
40,590
kg (CO2)
Total (GWP)
16,361
40,590
kg (CO2)
Toyota Corolla
111,296 276,122
km
*1 m2 of switchroom uses app 1.1m3 of concrete.
ECL Power System Standards / SF6
01020‐DPR‐3304 ‐ Revision 1
16‐Jul‐22
Page | 1
1.3 Conclusion




SF6 is bad for the environment – 23,500 times worse than CO2
Its annual leakage rate (11 panel board) is equivalent to a Toyota Corolla driving just 650km per
year; and can be monitored.
Proper end of life handling eliminates any discharge to atmosphere.
The environmental impact of using more concrete for an AIS switchroom outweighs the impact
of SF6 over the lifetime of the switchgear.
Considering the lifecycle impact on global warming, SF6 can be a better choice than AIS.
ECL Power System Standards / SF6
01020‐DPR‐3304 ‐ Revision 1
16‐Jul‐22
Page | 2
2. Appendices
Appendix 1
Switchroom Sizes .................................................................................................................. iv
ECL Power System Standards / Design Manual
01020‐DPR‐0001 ‐ Revision 1
21‐Jan‐22
Page | i
ECL Power System Standards / Design Manual
01020‐DPR‐0001 ‐ Revision 1
21‐Jan‐22
Page | iii
Appendix 1 Switchroom Sizes

01020‐DPR‐3304 Switchgear ‐ 33kV SF6 Design Practice
ECL Power System Standards / Design Manual
01020‐DPR‐0001 ‐ Revision 1
21‐Jan‐22
Page | iv
1
3
2
4
5
6
7
8
A
N
LY
A
B
600
600
600
=H04
=H07
600
600
800
1340
=H08
=H09
=H10
=H11
600
600
600
600
600
180
C
AL
180
=H06
U
C
=H05
3140
=H03
1700
=H02
SE
=H01
100
1000
O
1000
B
1500
N
9160
TOTAL AREA: 28.76m²
SCALE:1:50
D
IN
TE
R
D
E
E
GHA
Rev
1
Amendments
ISSUED FOR INFORMATION
Date
Name
14/02/21
O Duncan
Project No.
01020
Ergo
O Duncan
27/10/20
C Turney
Design
Drawn
Date
Check
Approved
01020-DRG-3362-2-1
File Name
1
2
3
Reference Designation:
DESIGN PRACTICE
SWITCHGEAR - 33KV
INDOOR - GIS - GHA
LAYOUT
www.ergo.co.nz
© Copyright Ergo Consulting Ltd
All rights reserved, unauthorised
reproduction prohibited
4
5
Scale at A2:
AS SHOWN
Drawing Number:
01020-DRG-3362
6
7
Drawing Function:
Document Type:
Sheet:
2
8
of
2
Rev:
1
1
3
2
4
5
6
7
8
A
180
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
B
=H01
=H02
=H03
=H04
=H05
=H06
=H06A
=H07
=H08
281201
3074
=H09
=H10
=H11
C
AL
87500
U
C
SE
O
B
800
N
1100
LY
A
1500
N
15760
D
R
D
TOTAL AREA: 88.60m²
IN
TE
SCALE:1:50
E
E
F400
Rev
1
Amendments
ISSUED FOR INFORMATION
Date
Name
14/02/21
O Duncan
Project No.
01020
Ergo
O Duncan
27/10/20
C Turney
Design
Drawn
Date
Check
Approved
01020-DRG-3363-2-1
File Name
1
2
3
Reference Designation:
DESIGN PRACTICE
SWITCHGEAR - 33KV
INDOOR - AIS - F400
LAYOUT
www.ergo.co.nz
© Copyright Ergo Consulting Ltd
All rights reserved, unauthorised
reproduction prohibited
4
5
Scale at A2:
AS SHOWN
Drawing Number:
01020-DRG-3363
6
7
Drawing Function:
Document Type:
Sheet:
2
8
of
2
Rev:
1