installation and testing of helium gas cooled superconducting...
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Installation and Testing of Helium Gas Cooled
Superconducting DC Cable at FSU-CAPS
Sastry Pamidi, Chul Han Kim, Lukas Graber, Danny Crook, Steve Ranner,
Bianca Trociewitz, and Steinar Dale The Florida State University - Center for Advanced Power Systems
Tallahassee, Florida
David Knoll, Dag Willen, Carsten Thidemann, and Heidi Lentge Ultera
19-Pamidi
11th EPRI Superconductivity Conference, October 28-30, 2013,
Houston, TX
Team Members
Sastry Pamidi
Chul Kim
Steinar Dale
Superconductivity Cryogenics
Danny Crook
Sastry Pamidi
Chul Kim
Facilities/
Electrical
Steve Ranner
Bianca Trociewitz
CAPS
NSWCCD, Philadelphia
Brian Fitzpatrick
Advice on Navy needs & relevance
Ultera/Southwire
David Knoll
Cable Fabrication
Cryo Dielectrics
Lukas Graber
Horatio Rodrigo
Steinar Dale
Benefits of Helium Gas Cooled
Superconducting Power Devices
Flexibility in operating temperatures (30 K–80 K)
Enhanced superconducting properties at lower temperatures
Lower temperatures allow higher power densities when
necessary
Larger temperature gradients can be maintained without
accompanying a phase change
Easier to integrate with other superconducting devices
operating under helium gas cooling
Increased flexibility in power system design optimization
Helium Gas Based Systems - Challenges
Low heat capacity of helium gas – requires high
pressures and flow rates for efficient heat removal
Helium gas has low dielectric strength – dielectric design
has to depend on the solid dielectric medium
Little experience on helium gas cooled superconducting
power devices
Commercial cryocoolers are inefficient –technological
developments necessary
Current Phase – Validate cryogenic and thermal issues
Monopole
Current rating: 3 kA and @ 77 K (up to 10 kA @ 40 K)
Voltage rating: 1 kV
Long-term Goal
100 MW -10 kA @ 50 K; voltage rating: 5 kV
Superconducting DC Cable Nominal Specifications
2G HTS - Cryoflex insulation – Ultera Triax Cable Design
Cryogenic Helium Circulation Systems
Operating Pressure: up to 250 psi, Expected flow rate: up to 10 g/s
AL 330
1
4
3
2
Cryo Fan
Stirling System
340 W @ 50 K
Cryozone Bohmwind Fan
50 psi 300 psi
Design Validation Studies on 1 m Cable Sections
The prototype cables performed well in gaseous helium
At 300 psi, PDIV is 7.4 kV peak
He inlet
Vacuum LN2
T- Sensors Cable
Current
Terminal
Schematic of the Terminations
G10 bar Temperature Sensors
TS #1
TS #8
TS #2
TS #5 TS #7 TS #6
TS #3 TS #4
G10 bar
Temperature Sensors
TS #9 TS #10 TS #11
TS #12
Cryostat
GHe In GHe Out 1 m or 30 m
cryostat
T Across the Terminations and the Cryostat
Without The Cable
∆T
30 m cryostat
Estimated Heat Leak From The Termination Tanks
Temperature Sensors
TS #1
TS #8
TS #2
TS #5 TS #7 TS #6
TS #3 TS #4
G10 bar
Temperature Sensors
TS #9 TS #10 TS #11
TS #12
GHe In GHe Out
Pictures of Cable Installation
As mass flow rate increases, the T decreases; T < 4 K @ 8 g/s for 3 kA
@ 50 K inlet T
Temperature Gradients Across the 30–m Cable
Little resistance between clamshell and cable terminal. 10 µ between the
current lead and the clamshell – room for improvement
@ 55 K
Resistances of the Current Contacts
Voltages measured on each of the three HTS layers
Only white noise measured up to 3000 A
No Voltage Rise Up To 3 kA
A Screenshot During One of The Tests
Current Voltage – HTS
layers
Voltage –
Copper layers
Summary
Cryogenic helium circulation system maintains a T<4 K
from inlet to outlet of the 30 m cryostat
Thermal load tests using simulated cable did not create large
temperature gradients
Experimental data on temperature gradients matched with
that of the thermal model
30 m cable performed well in GHe up to 3 kA
What is next?
We will attempt 4-5 kA with modified current feed throughs
High voltage tests in November/December 2013
We will look for funding for ±5 kV, 10 kA cable design
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