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1C O M E T 2 0 1 7
C O M E T 2 0 1 7W E L C O M E T O A
T E C H N I C A L P A P E R P R E S E N T A T I O N
2C O M E T 2 0 1 7
B Y J A V I E R M A N T I L L A
“INSULATION ANDSWITCHING IN
ENVIRONMENTALLYFRIENDLY GASES
3C O M E T 2 0 1 7
J A V I E R M A N T I L L AP R I N C I P A L E N G I N E E R
A B B S W I T Z E R L A N D
A B O U T T H E A U T H O R
Principal Engineer at ABB Switzerland
Holds an M.Sc. in Mechatronics and an M.Sc. in Power Engineering from the
RWTH Aachen University
Ten years experience in high voltage circuit breaker R&D with ABB Switzerland.
Main focus on environmentally friendly technologies.
Expert in CIGRE WG A3.26 and WG A3.32
Senior Member of IEEE
BRIEFBIO
4C O M E T 2 0 1 7
PILOT INSTALLATIONEWZ ZÜRICH
F irs t H igh -Vo l tage GIS (170 kV / 40
kA) with a l te rna t ive Insu l a t ion - and
Switch in g gas A irP lus™
HV and MV equ ipm ent w ith A irP lus™,
F law less opera t ion s ince August 2015
L E A R N M O R E
5C O M E T 2 0 1 7
Alternative Insulation and Switching GasesO v er v i ew f r om t h e « C u r r en t Z e r o C l u b » fo r C I G R E S C A 3 ( A u g u s t 2 0 1 6 )
A i r P l u s ™C5 Fluoroketones. Used as an additive to a background gas. Air
for insulation, CO2 for switching. Commercially available under
Novec 5110 from 3M
g 3C4 Nitriles. Used as an additive to a background gas.
Commercially available under Novec 4710 from 3M
6C O M E T 2 0 1 7
Insu lat ion- and Switch ing ga ses for H igh-Vol ta ge switchgear
G en er a l as p ec t s f o r t h e as s es s m en t o f I n s u l a t i on g as es
T r a d i t i o n a lTechnical functionality
Size / Footprint
Capital expenditure
Reliability and maintenance effort
F u t u r eEnvironmental impact / Global Warming Potential (GWP)
Operational costs due to regulations
Different regulations in different countries / regions
Environmental Impact Functionality
7C O M E T 2 0 1 7
Sca lab i l i ty
A p p l i c a t i on o f a l t e r n a t i v e g as es i n t h e w h o l e p or t f o l i o
B a s i c A s p e c t slThe insulation performance of alternative gases for AC and
impulse stresses is relative simple scalable
Especially the circuit breaker, but also disconnectors and
grounding switches have to be investigated experimentally due to
the complexity of the switching physics
Knowledge from decades of research with SF6 as Insulation- and
switching-medium have to be assessed for validity with respect to
the new gas mixtureU
n*
In
Product
8C O M E T 2 0 1 7
Insu lat ion- and Switch ing ga ses for H igh-Vol ta ge switchgear
A B B ’s A i r P l u s ™
P r o p e r t i e sC5-Fluorketones have a boiling-point of 26.5° C and have to be
mixed with a non-condensing buffer gas therefore a
mixture with N2 or CO2 (Circuit Breaker) is necessary
Additional admixture of O2 to avoid soot formation and toxic
decomposition products
Insulation- and switching performance close to SF6 today
achievable for minimum ambient temperatures of -5°C .. +5°C by
using only slightly modified SF6 - products
Typical mixing ratios in HV - applications:
C5-Ketones O2 N2 or CO2
4-7% 8-14% 79-88%
Typical minimum operating pressure around 6-7 bar
N2 or CO2
O2
C5F10O
9C O M E T 2 0 1 7
Example for new opt imiza t ion areas
T h er m od y n am i c P oy n t i n g E f f ec t [ 1 , 2 ]
D e w p o i n t s h i f tTests in climate chamber to confirm dewpoint
Buffer gas influences C5-vapor, shift of dewpoint
Effect strongly depends on gas properties
AirPlus™ : Shift of dewpoint around -0.7°C / bar
-> around +5-10 % better insulation performance
[1] R. Krishna and C. B. Panchal, “Condensation of a binary
vapour mixture in the presence of an inert gas,”
Chem. Eng. Sci., vol. 32, no. 7, pp. 741–745, 1977
[2] C. C. M. Luijten and M. E. H. van Dongen, “Nucleation at high
pressure. I. Theoretical considerations,”
J. Chem. Phys., vol. 111, no. 18, pp. 8524–8534, Nov. 1999
10C O M E T 2 0 1 7
D e c o m p o s i t i o n p r o d u c t s a f t e r e x t r e m e a r c i n g s t r e s s ( c i r c u i t b r e a k e r )G I S - B r e a k e r 2 4 5 k V / 5 0 k A a f t e r 8 x T 1 0 0 a , 3 . 1 M J a c c u m u l a t e d a r c i n g e n e r g y
C O N C L U S I O N 1
Gas analysis (EMPA, Switzerland)
C5-FK filling: 5.7 % at 7 bar , V = 380 Litres -> 6.8 Mol / 400 mbar
(partial pressure)
11C O M E T 2 0 1 7
AirP lus™ Consumpt ion Rate
F r o m n u m e r o u s d e v e l o p m e n tt e s t s
The measured decomposition products are not critical
Existing safety measures as known for SF6 are far on the safe
side when handling AirPlus
Decomposition rates of 0.14 mol/MJ (T10/T30) up to 0.5 mol/MJ
(T100a) have been measured
The «Aging» of the insulation gas by decomposition of the C5-
Fluorketones is not problematic for typical GIS breaker tank sizes
By correct dimensioning, the lifetime of the circuit breaker stays
determined by nozzle- and contact erosion
12C O M E T 2 0 1 7
Switch ing in A i rP lus
I n t r od u c t i on
G e n e r a l t o p i c sHigh-Voltage circuit breakers have to handle a large number of
switching gases safely (IEC 62271-100)
Today, the dominant technologies for SF6 - HV-interrupters are
self blast devices and for larger power the thermally supported
puffer breakers
All investigations have been performed with circuit breakers,
which originally were developed for SF6
Self blast interrupters as well as puffer unit with ratings up to 300
kV /50 kA were tested
No change of operating mechanism / linkage / contact speed
Only modifications were the new gas mixture, slightly increased
filling pressure and changes in the nozzle contour and flow cross
sections of the arc extinction system
13C O M E T 2 0 1 7
Switch ing performance 1/3
S m al l e r c u r r en t s - > c ap ac i t i v e / i n d u c t i v e / T 1 0 / T 3 0 / p h a s e op p os i t i o n
D e v e l o p m e n t t e s t s w i t h A i r P l u s ™Unmodified SF6 – Breaker: Problems at long arcing times (too
low no-load pressure), but already excellent interruption
performance for shorter arcing times
Modification of the flow cross section, adaptation to the changed
thermodynamic properties (density, sound velocity)
No modification of linkage and operating mechanism
Capacitive and inductive switching performance finally as good
as with SF6 (e.g. similar low chopping number)
14C O M E T 2 0 1 7
Switch ing per formance 2/3
S h or t l i n e f au l t s ( S L F, « t h er m al i n t e r r u p t i on » )
D e v e l o p m e n t t e s t s w i t h A i r P l u s ™With slightly modified nozzle contours around 80% of the thermal
interruption performance of the SF6-version can be achieved
Therefore the di/dt has to be down rated by 20%, if a short-line-
fault interruption capability is needed
«Decision time» for thermal interruption around 1 ms after
current zero, similar to SF6 -> SLF90 stays most critical case,
same as with SF6
Future improvements e.g. by providing higher blow pressure
15C O M E T 2 0 1 7
Switch ing per formance 3/3
H i g h s h or t c i r c u i t c u r r en t s T 6 0 – T 1 0 0 a / s
D e v e l o p m e n t t e s t s w i t h A i r P l u s ™General challenge for T100a - interruption: High temperature and
pressure, especially in self blast devices
With AirPlus the pressure build-up at long arcing times is lower
than with SF6, which is beneficial in this switching case
So far no problems by breakdowns to the tank due to hot exhaust
gases.
Nozzle contour and electric field in the arcing region, especially in
the so called diffusor area, has to be adapted
16C O M E T 2 0 1 7
Summary
C o n c l u s i o n a n d o u t l o o kCircuit Breakers with AirPlus™ reach the performance of the SF6-
version in most of the switching cases
For short-line-faults the maximum di/dt has to be downrated by
20% versus the SF6 – base version
Only minor modifications in the nozzle system in the breaker
Limitation today to indoor / warm climate installations
Technology is scalable for higher short circuit currents and
voltage ratings
Full compatibility for the unlikely case, that SF6 shall be used,
only exchange of the HV interrupter necessary in this case
Standard – products planned for 2020
Project-based installations possible on request