26-04-2012, 10:24 AM
High Temperature Superconducting Generator
e_ge_peer_review_2004_ornl.pdf (Size: 670.88 KB / Downloads: 72)
Areas of Emphasis
• Emissivity –Assessment of radiation heat load to HTS
rotor coil
• Quench and Stability – Characterization of HTS
tapes in order to predict coil performance during and
after transients and overload conditions
• Dielectrics – Performance of coil winding when
voltages are applied during normal operation of the
coil and from changes in the operating conditions of
the rotor
Emissivity Measurements
− Characterization of sample emissivity through the
calibration of background heat load w/o sample and
measurement of heat load with sample
• Quench and Stability
− Flux flow resistivity measured using short current
pulses (< 0.1 s) as sample warms up from 20 K to Tc.
• Dielectrics
− Conduct impulse breakdown, partial discharge and
aging studies for electrical insulation materials
selected by GE through the application of
representative high voltage DC impulses and AC
voltages
Characterization of SS BSCCO in progress
• Motivation: To give a
more accurate
description of
distribution of current
in the composite
superconductor during
and after disturbances
− Modified existing HTS
test apparatus to test
single tape and coils
at elevated fields up to
3 T) and currents up to
1 kA
− Preliminary data for
SS BSCCO at 2 T
perpendicular field
shown here
Pulsed aging characteristics predict lifetime of insulation system at rated voltage
Motivation – Dielectric
performance under pulsed
aging is key parameter for
insulation selection and
lifetime
• Lifetime relation is:
where n is a measure of
insulation lifetime
performance
• High voltage DC pulses
applied at or above PDIV
• Change in slope indicates
change in mechanism
• Aging data needed at
cryogenic temperature
Research Integration
• Weekly teleconferences with GE has lead to efficient use of
resources of ORNL and GE and ensures R&D objectives, efforts,
and results are in accord with project objectives
− Exchange of information between LANL and ORNL has lead to
productive discussion as to the role of materials within rotor vacuum
space and their impact on vacuum quality and calculations of heat
loads
• Presentations and publications during the year
− Emissivity poster presented at the Cryogenic Engineering
Conference in September 2003
− Panel session presentation on cryogenic insulation for coil
applications at Summer Power Meeting in June 2004
− Papers will be presented at the 2004 Applied Superconductivity
Conference and 2004 Conference on Electrical Insulation and
Dielectric Phenomena (both Oct. 2004)
• Web Sites
− ORNL Superconductivity Web Site includes Annual Reports,
Peer Review presentations and other project information
• www.ornl.gov/HTSC/htsc.html