Transcript EVALUATION OF HIGH-TEMPERATURE FLUORINATED ETHERS (PFPE) FOR POWER CONNECTORS OPERATING AT

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
[email protected]
Milenko BRAUNOVIC
MB Interface - Canada,
[email protected]
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Competitive Industry
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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
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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
Lubricant
Temperature
Composition
Range (°C)
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
• Maximum operating temperature range
• Formulation: base oil and additives
• Thickeners:
– not melting
– improved adhesion to the substrate
– lower wear rates
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Barcelona 12-15 May 2003
UV Resistance
Lubricant
Time to Failure
(hrs)
N1
>2051
N2
>2051
N3
>2051
S1
305
C1
>2051
• 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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Barcelona 12-15 May 2003
WEATHERING TESTER
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Barcelona 12-15 May 2003
Long-Term Temperature Exposure
Lubricant
Time to Failure
(hrs)
N1
720
N2
720
N3
>2400
S1
504
C1
>2400
• Forced Air Oven set to 2000C
• Exposure time: more than 2000 hrs
• Material Examination:
– Discoloration
– Cracking
– Hardening
JOHNSON_CA_author_ALPHA1_BLOCK1
Barcelona 12-15 May 2003
Appearance of the Lubricants
(Thermal Ageing)
PASSED
FAILED
BEFORE EXPOSURE
JOHNSON_CA_author_ALPHA1_BLOCK1
AFTER EXPOSURE
Barcelona 12-15 May 2003
Thermogravimetric Analysis (TGA)
140
WEIGHT LOSS
120
80
60
40
LUBRICANT S1
20
0
0
50
100
150
200
250
300
350
400
450
500
200
250
300
350
400
450
500
200
250
300
350
400
450
500
140
120
WEIGHT LOSS
Determination of thermal stability
Weight change measurement
Heating rate: 10 0C/min
N3 is stable up to 4000C
100
80
60
40
LUBRICANT N3
20
0
0
50
100
150
140
120
WEIGHT LOSS
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100
100
80
60
40
LUBRICANT C1
20
0
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0
50
100
150
TEMPERATURE (°C)
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
300
TEMPERATURE ( C)
RESISTANCE ( m)
µ
15
BETWEEN EQUALIZERS
9
6
ACROSS CONNECTOR
3
LUBRICANT C1
0
100
200
300
400
500
600
150
100
CONNECTOR
50
LUBRICANT C1
300
0
100
200
BETWEEN EQUALIZERS
9
6
ACROSS CONNECTOR
3
LUBRICANT N3
0
300
400
500
600
250
o
12
CONTROL CONDUCTOR
200
150
100
CONNECTOR
50
LUBRICANT N3
0
0
100
200
300
400
500
NUMBER OF CURRENT CYCLES
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CONTROL CONDUCTOR
200
0
0
TEMPERATURE ( C)
RESISTANCE (m)
µ
15
250
o
12
600
0
100
200
300
400
500
NUMBER OF CURRENT CYCLES
Typical data sample: lubricated Al to Al wedge connectors
N3 and C1 lubricants are the base formulation for effective high temperature
applications
JOHNSON_CA_author_ALPHA1_BLOCK1
600
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
JOHNSON_CA_author_ALPHA1_BLOCK1