Medium Voltage Cable Testing Technologies - … Commonly Used MV Cable Testing Methods. ... The...
Transcript of Medium Voltage Cable Testing Technologies - … Commonly Used MV Cable Testing Methods. ... The...
Presented by: Craig Goodwin
Medium Voltage
Cable Testing Technologies
Energization Sources:
• DC and DC Leakage Methods (Insulation
Resistance)
• Damped AC (20-300 Hz)
• AC – Power Frequency
• AC – Low Frequency (VLF – 0.1 Hz)
Most Commonly Used Cable Testing
Methods
Cable Diagnostic Technique:
• Withstand
• Tan Delta / Dissipation Factor
• Partial Discharge (Online and Offline)
• TDR (Time Domain Reflectometry)
• Thermal Imaging
• Others
• Combination of the Above - Smart
Most Commonly Used MV Cable Testing
Methods
Online versus Offline • Online testing is generally easier to
carry out, and is so called “non-destructive” its effectiveness is also limited..
• Offline testing, while requiring more preparation and setup, provides more insight into the cables true condition.
IEEE MV Cable Field Testing Chart
IEEE 400 (OmniBus) - 2012 Guide for Field Testing & Evaluation of the Insulation of Shielded Power Cable Systems Rated 5kV and above
IEEE 400.1 Field Testing of Laminated Cables Rated 5kV and above using DC.
IEEE 400.2 – 2013 Field Testing of Shielded Power Cables using Very Low Frequency VLF
IEEE 400.3 PD Testing of Shielded Power Cables in the Field Environment
Note 1 – there is no IEEE 60Hz field withstand testing
standard for MV Cables
Note 2 – there is no IEEE DC field testing standard for any
extruded cables.
• Potential Negative Impact on the Service
Reliability of Extruded Cables
• Ineffectiveness to Detect Serious Defects in
Cable Insulation
The Demise of the DC Hipot for Testing
MV Cables
Ref: IEEE400-2012
Concentric Neutral Design Vs. Tape Shielded
Cable Design Can Impact the Effectiveness and Usability
of Certain Diagnostic Techniques That are Rich in
Frequencies.
Which Energization Source and
Diagnostic Method/s to use and
when……….
IEEE 400 has an Informative Table in the
Appendix on the Applicability of Various Testing
Methods.
Comments
• Some Methods Were Not Analyzed Due to
Lack of Information / Data.
• Some Methods were shown to be useful and
some were Not.
• Table Does Not Address Tape Shielded
Cables and Mainly Focuses on Utility Style
CN Type.
Applicability Of Testing Methods
Test and Diagnostic Selection Matrix:
Expanded from IEEE 400 - 2012
Method New Extruded
Acceptance
Old Extruded
Maintenance
PILC
Laminat
ed
Old
Hybrid
Combo
Unjacket
ed
Accessories
(Splice &
Term)
Shield Type Tape CN Tape CN Mixed Mixed CN Mixed
DC Withstand
Testing
X X X X X X Limited
VLF AC Withstand
Test
Tan Delta /
Dissipation Factor
Test
Partial Discharge
Test – Offline
Limited
Limited Limited
Partial Discharge
Test – Online Limite
d Limited Limited Limited
Limited Limited
Smart VLF W/S Test
- combination with
TD
Smart VLF W/S Test
- combination with
PD
Limited
Limited Limited
TDR (Time Domain
Reflectometry) Useful Useful Not
Useful Useful Useful Limited Useful
• Testing Organizations Need to Be Aware of the
Changes in Standards and Guides
• A Need to Inform and Educate Customers / End
Users
• Careful Consideration When DC is Requested
• Choice of Test Method Often Determined By Age
and Type of Cable and the Intended Defect
Diagnosis
• Often, a Testing Strategy Involving a Combination
of Tests is Most Appropriate.
Conclusions