JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
EVALUATION OF HIGH-TEMPERATURE FLUORINATED ETHERS (PFPE) FOR
POWER CONNECTORS OPERATING AT EXTREME SERVICE CONDITIONS
Barry JOHNSON and Dmitry LADIN Tyco Electronics – Canada
Milenko BRAUNOVICMB Interface - Canada,
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
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
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
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
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Lubricants Selection
• Maximum operating temperature range• Formulation: base oil and additives• Thickeners:
– not melting– improved adhesion to the substrate– lower wear rates
Composition
Base/Thickener
N1 from -50 to +225 PFPE/PTFE
N2 from -50 to +225 PFPE/PTFE
N3 from -15 to +250 PFPE/PTFE
S1 from -43 to +232 Teflon
C1 from -20 to +300 PFAE/PTFE
Lubricant Temperature
Range (°C)
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
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
N1 >2051
N2 >2051
N3 >2051
S1 305
C1 >2051
Lubricant Time to Failure
(hrs)
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Long-Term Temperature Exposure
• Forced Air Oven set to 2000C• Exposure time: more than 2000 hrs• Material Examination:
– Discoloration– Cracking– Hardening
N1 720
N2 720
N3 >2400
S1 504
C1 >2400
Lubricant Time to Failure
(hrs)
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Appearance of the Lubricants (Thermal Ageing)
BEFORE EXPOSURE AFTER EXPOSURE
PASSED
FAILED
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Thermogravimetric Analysis (TGA)
• Determination of thermal stability
• Weight change measurement
• Heating rate: 10 0C/min
• N3 is stable up to 4000C
0 50 100 150 200 250 300 350 400 450 500
WE
IGH
T L
OS
S
0
20
40
60
80
100
120
140
LUBRICANT S1
0 50 100 150 200 250 300 350 400 450 500
WE
IGH
T L
OS
S
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
0 50 100 150 200 250 300 350 400 450 500
WE
IGH
T L
OS
S
0
20
40
60
80
100
120
140
LUBRICANT N3
LUBRICANT C1
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
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
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
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
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Results of the Current Cycling Tests
• Typical data sample: lubricated Al to Al wedge connectors
• N3 and C1 lubricants are the base formulation for effective high temperature applications
0 100 200 300 400 500 600
TE
MP
ER
AT
UR
E (
oC
)
0
50
100
150
200
250
300
0 100 200 300 400 500 600
RE
SIS
TA
NC
E
( m
)
0
3
6
9
12
15
LUBRICANT C1LUBRICANT C1
NUMBER OF CURRENT CYCLES
0 100 200 300 400 500 600
RE
SIS
TA
NC
E
(m
)
0
3
6
9
12
15
NUMBER OF CURRENT CYCLES
0 100 200 300 400 500 600
TE
MP
ER
AT
UR
E (
oC
)
0
50
100
150
200
250
300
LUBRICANT N3 LUBRICANT N3
BETWEEN EQUALIZERS
ACROSS CONNECTOR
BETWEEN EQUALIZERS
ACROSS CONNECTOR
CONTROL CONDUCTOR
CONNECTOR
CONTROL CONDUCTOR
CONNECTOR
µµ
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
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
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