BEV – Bundesamt für Eich- und Vermessungswesen
Dissemination Meeting „Power & Energy“, Noordwijk M.Garcocz, BEV Austria
The development and performance of high current shunts(> 20 A....100 A / 100 kHz)
for power measurement
BEV – Bundesamt für Eich- und Vermessungswesen
Page 2 of 14
Outline
Start April 2008: existing shunts for ac-dcexisting measurement methods
development of new measurement methods
BEV part:development of foil shunts for power measurement
mechanical modificationmeasurements
BEV – Bundesamt für Eich- und Vermessungswesen
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April 2008: starting point
SP: Cage Design
ac-dc ~ - 50 µA/A
SP BEV
BEV: Foil Design
ac-dc ~ + 50 µA/A
BEV – Bundesamt für Eich- und Vermessungswesen
Page 4 of 14
measurement capabilities:
existing:
BEV: ac-dcSP: ac-dc, dc, phase up to 1.500 Hz calculated from L and C
new developed measurement methods:
INRIM: phase angle errorCMI: TCR (temperature coefficiant of resistance)
PCR (power coefficient of resistance)
work in progress:SP: expanding L to pH and 100 kHz
PXI phase comparatorCMI: impedance
ISTITUTONAZIONALEDI RICERCAMETROLOGICA 5
Phase comparator
A phase comparator was built for the measurements of phase differences between two shunts.
Basic circuit of the phase comparator. SH1 and SH2
denote the two shunts being compared. Two active
guarded transformers (AGTs) are employed as wideband
decoupled precision transmitters.
The current generator was assembled by
connecting a calibrator in the ac voltage
function that supplies a transconductace
amplifier.
6Voltage source
Transconductanceamplifier
Oil bath with reference standard
oil bath temperaturecontrol
Dual channel DMM
Air box Air box temperature controlshunt
DC characterization of the shunts
• Method: measurement of ratio of output voltages of the tested and the reference standard by dual channel multimeter
• PC measured and calculated in current range of 50% - 100% of nominal current
• TC measured in temperature range from 18 °C up to 28(30) °C at 1/10 of nominal current
• Typical values for foil shunts:
PC < ± 4 ppm TC from -2.8 ppm to +8 ppm
Set up for TC measurement
E
E
X
XR
U
UR ⋅=
BEV – Bundesamt für Eich- und Vermessungswesen
Page 7 of 14
motivation for new foil shunts
„Old design“
– very heavy units (28.5 kg for 100 A)
– long warmup time (~ 2 hours)
– dc properties not satisfying
– very time- consuming fabrication
„New design“
– reduced weight (2.9 kg for 100 A)
– warmup time ~ 10 min
– dc property?
BEV – Bundesamt für Eich- und Vermessungswesen
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foil shunt - principle
OUTIN
BEV – Bundesamt für Eich- und Vermessungswesen
Page 9 of 14
mechanical modification
currentIN
voltageOUTventilator
BEV – Bundesamt für Eich- und Vermessungswesen
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temperature distribution forcerd air cooled foil shunts
54
56
58
60
62
0 1 2 3 4 5 6 7 8
Temperature distribution foil shuntfan position: centered
B50-1; 100 A
Position Pt 100
temp
[°C]
BEV – Bundesamt für Eich- und Vermessungswesen
Page 11 of 14
EMRP Coaxial Foil Shunts
BEV – Bundesamt für Eich- und Vermessungswesen
Page 12 of 14
coaxial foil shunts ac-dc values
-20.0
0.0
20.0
40.0
60.0
80.0
100.0
120.0
140.0
160.0
1 10 100
BZ1 30µ 42.28 mΩΩΩΩ nom. 16 A
BZ2 45µ 24.29 mΩΩΩΩ nom. 20 A
BZ3 30µ 8.64 mΩΩΩΩ nom. 100 A
BZ4 45 µ 5.28 mΩΩΩΩ nom. 100 A
BM1 23µ 15.20 mΩΩΩΩ nom. 50 A
BM2 70µ 5 mΩΩΩΩ nom. 100 A
BM3 70µ 5 mΩΩΩΩ nom. 100 A
EMRP foil shunts BEV
ac-d
c c
urr
en
t tr
an
sfe
r d
iffe
ren
ce
[µ
A/A
]
frequency [kHz]
BEV – Bundesamt für Eich- und Vermessungswesen
Page 13 of 14
DC - Power Coefficient
-200
-150
-100
-50
0
50
0 10 20 30 40 50 60 70 80 90
BZ3
BZ4
BM1
BM2
BM3
B20-3
B40-2
B80-2
CMI measurements on BEV shunts
Power [W]
relative change of
dc- resistance
[µΩ/Ω]
all curves referenced to 1% nominal power
Power Coefficient Resistance
ZERANIN 30 µm
ZERANIN 45 µm
MANGANIN 70 µm
MANGANIN 23 µm
old design 23 µm
BEV – Bundesamt für Eich- und Vermessungswesen
Page 14 of 14
DC - Temperature Coefficient 20...30°C
-60
-40
-20
0
20
40
60
80
100
17 20 23 26 29
B80-2
BZ3
BZ2
BZ4
BM1
BM2
BM3
B40-2
B50-1
B20-3
Temperature Coefficient Resistance
temperature [°C]
relative change of
dc- resistance
[µΩ/Ω]
ZERANIN 45 µm
ZERANIN 30 µm
MANGANIN 23 + 70 µm
MANGANIN 23 µm
TC with full power
CMI measurements on BEV shunts
all curves referenced to 18°C
meas. current = 1/10 of nominal
BEV – Bundesamt für Eich- und Vermessungswesen
Page 15 of 14
Temperature Coefficient 20...70°C
-1600
-1400
-1200
-1000
-800
-600
-400
-200
0
200
20 25 30 35 40 45 50 55 60 65 70 75
MANGANIN 23µm
MANGANIN 70µm
ZERANIN 45µm
Temperature [°C]
change of resistance
relative to start
[µΩ/Ω]
startday 1 day 2
day 3
day 4
BEV – Bundesamt für Eich- und Vermessungswesen
Page 16 of 14
thermal treatment
-3500
-3000
-2500
-2000
-1500
-1000
-500
0
500
20 30 40 50 60 70 80 90 100
Temperature [°C]
change of resistance
relative to start
[µΩ/Ω]
180 °C
MANGANIN 23µm
ZERANIN 45µm
MANGANIN 70µm
BEV – Bundesamt für Eich- und Vermessungswesen
Page 17 of 14
cage design versus foil design (>20 A...100 A)
ac-dc dc phase
Cage Design
Foil Design
Measurements performed:BEV: ac-dc; some dc
CMI: dc temperature + power coefficient; impedance measurementsINRIM: phase angle error measurementsSP: ac-dc; inductance; phase
