Thermal Analysis of Two Braze Alloys to Improve the Performance of a Contactor During the Temperature Rise Test - PowerPoint PPT Presentation


Title: Thermal Analysis of Two Braze Alloys to Improve the Performance of a Contactor During the Temperature Rise Test


1
Thermal Analysis of Two Braze Alloys to Improve
the Performance of a Contactor During the
Temperature Rise Test
G. Contreras1, E. Gutierrez-Miravete2 1 General
Electric, Plainville, CT 2 Rensselaer Polytechnic
Institute, Hartford, CT
2
Electrical Contactors
3
The Brazing Process for Contactors
  • Brazing
  • Metal Joining Process
  • Use of a filler metal (braze alloy)
  • Capillary action
  • Filler Metal with lower Melting Temperature
  • Melting Temperature above 450 C

Typical Contact Assemblies
4
Use of COMSOL
  • Determine the thermal response of the contact
    terminals
  • during the making and breaking process
  • during the temperature rise test
  • Joule Heating / Electro-Thermal Interaction
  • Heat Transfer by Conduction (ht)
  • Conductive Media
  • 2D Axis-symmetric Model ( Arc - Transient )
  • Overload Test Validation by comparison to prior
    work
  • 3D Model ( Joule Heating Steady State )
  • Steady State conditions are aimed during the
    temperature rise test Present work

5
Material Considerations
Contact Tip Silver Cadmium Oxide
(90/10) Carrier Brass Braze Alloys Braze750
Silfos
 

6
Geometry Temperature Rise Test
Contact Assembly - 3D Model
 
Tip Diameter 6 mm Arm Length 8 mm Width 6mm

7
Temperature Rise Test Details
  • Test Required per UL508
  • Standard for Safety for Industrial Control
    Equipment
  • Parameters
  • Under normal conditions
  • While carrying its rated current continuously
  • While device is mounted as intended in use
  • Until temperature readings are constant
  • No change after three consecutive readings

Determine the maximum stable temperature reached
by the contact terminals after passing the rated
current of the contactor.
8
TRT -Test Setup
  • Wire Size is 6 AWG ( 1.25 FLA )
  • Contacts are wired in Series.
  • Coil is energized to close contacts and pass the
    current.
  • The contactor is rated for 30 amps. The
    contactor is tested at 100 of the rated current.
  • Thermocouples are placed on the contact
    assemblies terminals.
  • Temperature Readings are taken every 15 minutes
    for 6 hours or until temperature readings are
    stable.

9
Temperature Rise (experimental)
10
Governing Equations
Joule Heating
Q resistive heating W/m3 J current density
Amp/m2 s electric conductivity S/m
  • The resistive heating Q is the Joule heat due
    to current flow.
  • Term is predefined as the source term when
    using the Joule-Heating predefined Multiphysics
    coupling.

11
Validation of Electro Thermal Model
Thermal-electric solid element from
ANSYS Analysis for a locked rotor test that is
rated 240 amps Joule Heating was imposed as
current coming into the model Arc Heating was
imposed on the model as heat flux Temperature
reached on the contact surface when arc heating
is applied for 3 milliseconds. Same model was
developed in COMSOL using the electro-thermal
module with triangular quadratic elements.
12
Validation of Simulation using Comsol
13
3D Model (Joule Heating-Steady State)
14
Analysis Results - temperature rise
Braze 750 with perfect bonding Max temperature
reached
Braze 750 with imperfect bonding Max temperature
reached
15
Analysis Results - temperature rise
Silfos with perfect bonding Max temperature
reached
Silfos with imperfect bonding Max temperature
reached
16
Conclusions
  • COMSOL proved to be a realiable tool as we were
    able to able to predict the same results from
    previous jobs ( locked rotor )
  • Same methodology was applied with a 3D model to
    predict the performance during a temperature rise
    test
  • Experimental data showed that Braze 750 had a
    better performance on the temperature rise test
  • Validation in COMSOL was in agreement with
    experimental data
  • Present evaluation was made for two braze alloys
    with contact tips using Silver Cadmium Oxide
  • New materials on contact tips ( RoHS requirements
    ) will require extensive testing
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Thermal Analysis of Two Braze Alloys to Improve the Performance of a Contactor During the Temperature Rise Test

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Title: Thermal Analysis of Two Braze Alloys to Improve the Performance of a Contactor During the Temperature Rise Test


1
Thermal Analysis of Two Braze Alloys to Improve
the Performance of a Contactor During the
Temperature Rise Test
G. Contreras1, E. Gutierrez-Miravete2 1 General
Electric, Plainville, CT 2 Rensselaer Polytechnic
Institute, Hartford, CT
2
Electrical Contactors
3
The Brazing Process for Contactors
  • Brazing
  • Metal Joining Process
  • Use of a filler metal (braze alloy)
  • Capillary action
  • Filler Metal with lower Melting Temperature
  • Melting Temperature above 450 C

Typical Contact Assemblies
4
Use of COMSOL
  • Determine the thermal response of the contact
    terminals
  • during the making and breaking process
  • during the temperature rise test
  • Joule Heating / Electro-Thermal Interaction
  • Heat Transfer by Conduction (ht)
  • Conductive Media
  • 2D Axis-symmetric Model ( Arc - Transient )
  • Overload Test Validation by comparison to prior
    work
  • 3D Model ( Joule Heating Steady State )
  • Steady State conditions are aimed during the
    temperature rise test Present work

5
Material Considerations
Contact Tip Silver Cadmium Oxide
(90/10) Carrier Brass Braze Alloys Braze750
Silfos
 

6
Geometry Temperature Rise Test
Contact Assembly - 3D Model
 
Tip Diameter 6 mm Arm Length 8 mm Width 6mm

7
Temperature Rise Test Details
  • Test Required per UL508
  • Standard for Safety for Industrial Control
    Equipment
  • Parameters
  • Under normal conditions
  • While carrying its rated current continuously
  • While device is mounted as intended in use
  • Until temperature readings are constant
  • No change after three consecutive readings

Determine the maximum stable temperature reached
by the contact terminals after passing the rated
current of the contactor.
8
TRT -Test Setup
  • Wire Size is 6 AWG ( 1.25 FLA )
  • Contacts are wired in Series.
  • Coil is energized to close contacts and pass the
    current.
  • The contactor is rated for 30 amps. The
    contactor is tested at 100 of the rated current.
  • Thermocouples are placed on the contact
    assemblies terminals.
  • Temperature Readings are taken every 15 minutes
    for 6 hours or until temperature readings are
    stable.

9
Temperature Rise (experimental)
10
Governing Equations
Joule Heating
Q resistive heating W/m3 J current density
Amp/m2 s electric conductivity S/m
  • The resistive heating Q is the Joule heat due
    to current flow.
  • Term is predefined as the source term when
    using the Joule-Heating predefined Multiphysics
    coupling.

11
Validation of Electro Thermal Model
Thermal-electric solid element from
ANSYS Analysis for a locked rotor test that is
rated 240 amps Joule Heating was imposed as
current coming into the model Arc Heating was
imposed on the model as heat flux Temperature
reached on the contact surface when arc heating
is applied for 3 milliseconds. Same model was
developed in COMSOL using the electro-thermal
module with triangular quadratic elements.
12
Validation of Simulation using Comsol
13
3D Model (Joule Heating-Steady State)
14
Analysis Results - temperature rise
Braze 750 with perfect bonding Max temperature
reached
Braze 750 with imperfect bonding Max temperature
reached
15
Analysis Results - temperature rise
Silfos with perfect bonding Max temperature
reached
Silfos with imperfect bonding Max temperature
reached
16
Conclusions
  • COMSOL proved to be a realiable tool as we were
    able to able to predict the same results from
    previous jobs ( locked rotor )
  • Same methodology was applied with a 3D model to
    predict the performance during a temperature rise
    test
  • Experimental data showed that Braze 750 had a
    better performance on the temperature rise test
  • Validation in COMSOL was in agreement with
    experimental data
  • Present evaluation was made for two braze alloys
    with contact tips using Silver Cadmium Oxide
  • New materials on contact tips ( RoHS requirements
    ) will require extensive testing
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