1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite...
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![Page 1: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/1.jpg)
1
Erik Nordlund, Dept. of Electrical Engineering
Testing of Silver-, Copper- and Electro-Graphite Brush
Materials for Slip Ring Units
![Page 2: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/2.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Why slip rings?
The Four Quadrant Transducer (4QT) system
![Page 3: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/3.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Slip ring topology
![Page 4: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/4.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Test setup
Integral motor
Torque meter
Slip rings
ACCurrent
Signal slip rings
A UTo data logger for temperatures
Brushes
![Page 5: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/5.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Test setup
PT-100 temperature sensors
Signal slip rings
Measurement instruments
![Page 6: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/6.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Losses in slip rings
1000 1500 2000 2500 3000 3500 4000 4500 500050
100
150
200
250
300
350
400
Speed [rpm]
Fri
ctio
n l
oss
es
[W]
2.6 A/cm2
5.2 A/cm2
7.8 A/cm2
10.4 A/cm2
13 A/cm2
Friction losses
1000 1500 2000 2500 3000 3500 4000 4500 50000
50
100
150
200
250
Speed [rpm]
Ele
ctri
cal
Loss
es
[W] 2.6 A/cm 2
5.2 A/cm 2
7.8 A/cm 2
10.4 A/cm 2
13 A/cm 2
Electric losses
![Page 7: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/7.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
The different brushes
Material• Brush 1 Silver – Graphite• Brush 2 Copper – Graphite• Brush 3 Electro – Graphite• Slip ring Brass• Holder Brass
![Page 8: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/8.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Speed dependency
Temperature rise
Electrical lossesFriction losses Contact voltage drop losses
Total losses
![Page 9: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/9.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Current dependency
Friction losses Electric losses
Total losses Temperature rise
![Page 10: 1 Erik Nordlund, Dept. of Electrical Engineering Testing of Silver-, Copper- and Electro-Graphite Brush Materials for Slip Ring Units.](https://reader035.fdocuments.in/reader035/viewer/2022070401/56649f1c5503460f94c32f56/html5/thumbnails/10.jpg)
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Erik Nordlund, Dept. of Electrical Engineering
Conclusions
• A strong correlation is shown “as expected” between the total losses and the temperature rise
• The temperature rise is mostly dependent of the current density in the brushes.
• The temperature rise with constant current and different speed is small
• The most suitable brush for the specified application is the copper-graphite brush.
• Due to:• Lowest total losses• Low temperature rise• Cheaper material than the silver-graphite brush with the
most common behavior• The electro-graphite brush performed inefficiency for this type of
operation
Temperature rise constant speed different currents
Temperature rise constant current different speedTotal losses Total losses