EVALUATION OF HIGH-TEMPERATURE FLUORINATED ETHERS (PFPE) FOR POWER CONNECTORS OPERATING AT EXTREME SERVICE CONDITIONS Barry JOHNSON and Dmitry LADIN Tyco Electronics

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EVALUATION OF HIGH-TEMPERATURE FLUORINATED ETHERS
(PFPE) FOR POWER CONNECTORS OPERATING AT EXTREME
SERVICE CONDITIONS Barry JOHNSON and Dmitry
LADIN Tyco Electronics Canada
bjohnson_at_tycoelectronics.com Milenko
BRAUNOVICMB Interface - Canada,mbinterface_at_yahoo
.com
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Competitive Industry

• From system growth to prolonging the operating
  life
• Increased energy consumption in densely populated
  areas
• Transmission/Distribution lines carry greater
  loads
• Operating temperature of conductors raised beyond
  1300C
• New type of high temperature conductor (ACSS)
• Stability of power connections at extreme
  operating conditions

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Lubrication of Power Connections

• Contact aid compounds commonly used for Al and Cu
• Contact zone protection
• Low thermal stability of currently used compounds
• Inertness and low viscosity of fluorinated ethers
• PFPE-based lubricants can sustain operating
  temperatures as high as 2000C

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Lubricants Selection

• Maximum operating temperature range
• Formulation base oil and additives
• Thickeners
• not melting
• improved adhesion to the substrate
• lower wear rates

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UV Resistance

• Per ASTM G-53-95 and ASTM D-638-95
• Accelerated Weathering Tester cycles of 4 hrs
  UVB at 600C, followed by 4 hrs of condensation at
  500C
• Lubricant failed no longer can be spread and/or
  has severe cracking

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WEATHERING TESTER
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Long-Term Temperature Exposure

• Forced Air Oven set to 2000C
• Exposure time more than 2000 hrs
• Material Examination
• Discoloration
• Cracking
• Hardening

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Appearance of the Lubricants (Thermal Ageing)
PASSED FAILED
BEFORE EXPOSURE AFTER EXPOSURE
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Thermogravimetric Analysis (TGA)

• Determination of thermal stability
• Weight change measurement
• Heating rate 10 0C/min
• N3 is stable up to 4000C

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Current Cycling Tests

• Test I measured contact resistance and
  temperature of lubricated Al-to-Al busbar bolted
  joints
• Thin layer of the lubricant spread over
  overlapping zones
• Joints repeatedly heated up to 2000C (for 5 min)
  and cooled to ambient temperature

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Current Cycling Tests

• Test II wedge connectors assembled with 336.4
  kcmil ACSS conductors
• Followed modified ANSI 119.4 Class AA procedure
• Temperature of the control conductor was raised
  to 2000C

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Results of the Current Cycling Tests
µ
µ

• Typical data sample lubricated Al to Al wedge
  connectors
• N3 and C1 lubricants are the base formulation for
  effective high temperature applications

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Discussion Conclusions

• Two PFPE lubricants with sufficient UV and
  thermal ageing stability are identified
• The lubricants were effectively utilized as
  contact-aid compounds in current cycling tests
• Results obtained under controlled laboratory
  conditions
• Suggested materials should be subjected to the
  field service conditions
• Necessary fillers and metallic additions are to
  be incorporated to make HT contact-aid compounds