IEEE Power Electronics Magazine - June 2022 - 59

■ The most unique property is the transient
related peak appearing at the
load is always less than the MOV's
clamping voltage.
Table 3 provides a comparison of number
of components for differential mode
section in two commercial version (sold
in New Zealand) and the number of components
in the SCASA based commercial
product. This clearly shows, that SCASA
uses much lower number of components,
than a high-end commercial SPD.
Table 4 depicts another key performance
related characteristic of SCASA
technique. By the introduction of the coupled
inductor into the SCASA technique,
with a SC based sub-circuit, it increases
the lifetime of the varistors used inside
the circuit significantly. Table 4 compares
the cases of failures of MOVs used
as Varistor 1 and Varistor 2 [Figure 14
(b)] and the required number of repeated
surges to destroy them. For 6 kV surges
both versions (when individually tested)
failed even before 40 repeats, whereas
overall SCASA system could withstand
much above 100 repeated surges, without
any degradation of the components.
Appendix B1 in Ref [1] is a summary
of commercial test report on Smart TVIQ2
product subjected to UL 1449 3rd Edition
recommendation. It also gives an overview
of how to interpret test data created
by the test procedure, utilizing a commercial
lightning surge simulator (LSS) of the
type Noiseken LSS 6230 and Tektronix
TPS 2014 oscilloscope.
Figure 15 depicts the measured perTable
4. Destructive Varistor Tests on the Commercial Product.
Varistor
(Ref:figure 14(b))
Varistor 1
(431KD14)
Varistor 2
(431KD10 )
Rated energy (J)
(Based on 10/1000 µs
test waveform)
66
Rated AC
Voltage (V)
275
Test result
Sample 1-Failed after
7 surges of 6 kV peak
Sample 2-Failed after
10 surges of 6 kV peak
132
275
Sample 1-Failed after
34 surges of 6 kV peak
Sample 2-Failed after
27 surges of 6 kV peak
1,200
1,000
800
600
400
200
Commercial 1
Commercial 2
SCASA With Two Varistors
01234
LSS Output Voltage Setting (kV)
(a)
1,000
900
800
700
600
500
vvar
56 7
vload
01234
LSS Output Voltage Setting (kV)
(b)
formance of the SCASA implementation,
where Figure 15(a) compares its performance
with two common commercial
products and Figure 15(b) depicts the unique property of
load seeing a lower transient related peak voltage than the
clamping voltage of the varistors used.
Ongoing Developments
SCASA's commercial success has led us to develop the
basic technique further to absorb high transient joules
and also to have significant surge-repeat-endurance. One
area where significant ongoing research is in the selection
of magnetic cores including the gapped ferrite cores of
high relative permeability, with lower costs than powdered
alloys. The other area will be the advanced versions
of SCASA topology based on complex core combinations.
References [17], [18] provide our early results, in ongoing
Ph.D projects.
56 7
FIG 15 Performance of SCASA technique (a) comparison with traditional SPDs
(b) lower load peak voltage than the varistor voltage.
Conclusion
Supercapacitor assisted surge absorber (SCASA) technique
is a new technique useful for surge protectors where a SC
based sub-circuit is effectively combined with traditional
surge absorber devices such as MOVs. This work proves the
capability of SC based long time constants in surge absorbers,
as a unique new family of surge protectors adhering to
UL 1449 3rd Ed standard. A unique property of the SCASA
technique is to achieve a lower transient related peak voltage
at the load, compared to the Varistor's clamping voltage
in a commonly used SPD techniques. With repeated surge
applications, as per UL 1449, the MOVs in SCASA protectors
do not deteriorate with the applied number of surges.
Proper selection of a magnetic core is key requirement for
the successful implementation in a commercial SPD.
June 2022 z IEEE POWER ELECTRONICS MAGAZINE 59
Voltage (V)
Voltage (V)
IEEE Power Electronics Magazine - June 2022

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