Defect Blog

Monitoring Detects Failing Joint

By: Ben Lanz, John Kreso and Bill Corrente

This summary describes IMCORP’s findings during the dissection and root cause analysis of a substandard joint removed from a system feeding a critical facility.  The IMCORP Factory Grade® technology targeted 7 of 51 joints that had sub... Read Article

Water Trees Don't Fail Cable

By: Ben Lanz and Bill Corrente

Posted in: Wind, Utility, Solar, Renewable, Generation, Facility, Cable

Water Trees Don't Fail Cable Decades ago we learned from many of the leading industry experts that water trees fail cable and we believed this industry myth until we collected cable performance data using the  IMCORP Factory Grade&re... Read Article

Termination Damaged but Passed by VLF Test

By: Ben Lanz and Bill Corrente

Posted in: Workmanship, Wind, Utility, Solar, Renewable, Generation

Termination Damaged but Passed by VLF Test Our utility client asked us to commission cable systems at a new generation facility after experiencing several termination failures.  The installation contractor had already tested the cable syste... Read Article

Electrical Tree in an Aged Cable

By: IMCORP

Electrical Tree in Aged URD Cable At a client utility in the Midwest, IMCORP was performing a Factory Grade® assessment on an aged 2615 foot long solid dielectric cable.  IMCORP identified the location of the defect and provided Loc... Read Article

PD Activity Identified During Assessment of Aged Utility Cable

By: IMCORP

Posted in: Utility, Cable

During the reliability assessment of aged underground residential distribution (URD) cable systems at a mid-western electric utility, one particular cable sample was found to exhibit low levels partial discharge (PD) activity. These PD sites were e... Read Article

Low Signal Magnitude (pC) but Serious Cable Defect

By: Ben Lanz and Bill Corrente

Posted in: Workmanship, Wind, Utility, Renewable, Cable

While commissioning new generation project in the multiple defects were identified within the cable system. One particular cable exhibited defects in the dozens of low magnitude partial discharge signals at two times the operating voltage.  Th... Read Article

Wind Farm Cable with a Small but Very Serious Defect

By: IMCORP

Posted in: Workmanship, Wind, Renewable

After performing an initial Factory Grade® assessment at a renewable energy plant, a cable was found to have near end termination discharge at operating voltage. The on-site crew attempted to mitigate the Partial Discharge (PD) activity by disa... Read Article

Oil Damaging to Cable Semicon

By: IMCORP

While performing a Factory Grade® assessment on a cable at a utility client in the southern part of the US, substandard partial discharge (PD) was observed near a termination. Upon visual inspection it was noted that the cable’s ou... Read Article

Manufacturer’s Defect: Conductor Shield Protrusion

By: IMCORP

During the Factory Grade® commissioning of a new cable system at a critical generation facility, substandard partial discharge (PD) activity (per ICEA S94-649) was observed at numerous points in a few cable systems.  The client... Read Article

Severe Termination Damage at a Utility

By: IMCORP

An IMCORP Field Engineer was performing a Factory Grade® asessement for a utility client. The assessment results showed partial discharge (PD) at operating voltage in the far end open air termination. Upon investigation of the far end ... Read Article

Multiple Defects Found at a Wind Farm

By: IMCORP

Just a few weeks ago, IMCORP was performing its Factory Grade® assessment at a wind site in Canada. The assessment indicated substandard partial discharge (PD) at the near end termination. To determine the source of the PD, the assist ... Read Article

Residual Semicon Under a Cable Termination

By: IMCORP

IEEE 386 Non-Compliant While performing a Factory Grade® assessment for a utility client, IMCORP detected sub-standard partial discharge (PD) activity in URD cable elbow termination. After the assist crew cleaned and applied dielectric ... Read Article

Invisible Semicon Damage Near at Termination

By: IMCORP

IEEE 386 Non-Compliant While performing a Factory Grade® assessment, IMCORP found partial discharge(PD) activity near a separable connector (T-body) termination. Visual inspection of the termination showed no indication of a problem. Th... Read Article

Issues with Termination at a Utility

By: IMCORP

IEEE 386 Non-Compliant Earlier this year, IMCORP was performing its Factory Grade® assessment for a utility client and detected PD at 1.3 times operating voltage at the far end termination (not meeting IEEE 386 requirements). The... Read Article

Delaminated Ambers in Cable Insulation

By: IMCORP

Cable not meeting ICEA S-94-649 standard IMCORP was conducting a Factory Grade® assessment on a cable system when this pair of defects was pinpointed.  The defects were located less than 45 meters (150 feet) apart and appeared ... Read Article

Severe Cable Defect at a Wind Farm

By: IMCORP

Cable not meeting ICEA S-94-649 standard IMCORP was again contracted to commission a wind farm collector system using  Factory Grade® technology.  During the course of assessment, the IMCORP Field Supervisor came across an e... Read Article

Improper Installation of Stress Control

By: IMCORP

A newly installed critical cable system experiencing multiple cable and accessory failures shortly after commissioning. The sites' underground cable system had initially been tested using a very low frequency (VLF) method, but after multipl... Read Article

Termination Failure at a Wind Farm

By: IMCORP

This client used Factory Grade® technology to commission a shielded power cable system, linking a substation with a generation plant. We found twelve cable terminations on the substation end of the circuits performing well below t... Read Article

Improper Semicon Cutback On A Cold Shrink Termination

By: IMCORP

The above image, taken at a nuclear power plant, shows a jagged semicon cutback on an open-air cold shrink termination. The cable owner first used Tangent Delta (TD) and Very Low Frequency (VLF) tests believing these were sufficient to assure r... Read Article

Stone in Cable 176m (578ft) from Termination

By: Ben Lanz and Bill Corrente

Posted in: Backfill, Cable, Facility, Generation, Renewable, Solar, Utility, Wind, Workmanship

IMCORP’s  Factory Grade® assessment discovered a substandard  location while commissioning the cable systems at a generation facility. The client used IMCORP’s Location Matching service to pinpoint the defect location. N... Read Article

PD Activity in a Y Joint at a Nuclear Facility

By: IMCORP

Posted in: Workmanship, Generation

IMCORP conducted its Factory Grade® assessment on a critical loop at a government nuclear facility in southeast USA. This particular PD occurred at a Y-joint located 185 ft. and had an inception voltage of Uo. PD a... Read Article

Non Radial Cutback on a Cold Shrink Joint at a Wind Farm

By: IMCORP

Posted in: Workmanship, Wind, Generation

This cold shrink joint was a part of a feeder cable system at a wind farm site that failed to pass IEEE 404 specifications. Even after the Factory Grade® assessment found this joint to be substandard, the cable system's contracto... Read Article

Non Radial Power Cable Cutback at a Power Plant

By: IMCORP

This is the open-air termination of a solid dielectric cable featuring ethylene propylene rubber insulation (the salmon colored section). Initially, this cable was deemed to be in good working order after passing a one-hour, 3Uo VLF withstand tes... Read Article

Misplaced Stress Relief Material at a Utility

By: IMCORP

Posted in: Workmanship, Utility

This particular open-air termination transitions an underground line to a riser. Although visual inspection indicated that the cable was properly installed (it is difficult to see the mastic placement with the termination installed), the cable ... Read Article

Semicon Defect During Installation

By: IMCORP

Posted in: Workmanship, Wind, Generation, Cable

The cable displayed here was compromised as a result of a semicon cutback error that was not recognized as a defect by the installer. When the cutback was made, the installer created a slight spiral instead of a radial cut leaving a thin slice of... Read Article

Issues Performing Cutback on Out of Round Power Cable at a Wind Farm

By: IMCORP

Posted in: Workmanship, Wind, Generation

Featured here are medium voltage feeder cables at a wind farm substation in South Dakota. These cables are the site’s most critical link, handling the output of 10 to 20 turbines. IMCORP Factory Grade® technology found that ... Read Article

Improper Heat Shrink Application

By: IMCORP

Posted in: Workmanship, Wind, Generation

These images show the development of a medium voltage cable failure in an open-air heat shrink termination. The first image (left) shows the IEEE 48 non-compliant heat shrink at the termination that was located by the IMCORP's Factory ... Read Article

Power Cable Degassing

By: IMCORP

Posted in: Workmanship, Wind, Generation

These images show cross-sections of a medium voltage power cable that was installed at a wind farm in Wyoming. In this case, the IMCORP Factory Grade® technology indicated partial discharge activity on a section of cable. The PD l... Read Article

Cable Manufacturer Defect During Repair

By: IMCORP

Posted in: Workmanship, Wind

IMCORP's Factory Grade® assessment indicated a PD site in an underground medium voltage power cable. Initial inspection of the PD site did not show any evidence of an issue. According to the latest study no visual evidence is reported ... Read Article

Whittled Cutback on Power Cable at a Co-op Utility

By: IMCORP

Posted in: Workmanship, Wind

This image shows a 7.2 kV (medium voltage) power cable system at a co-op utility in rural Missouri that supplies power to a residential area.  IMCORP's Factory Grade® assessment indicated PD activity at the separable connector... Read Article

Power Cable Termination Cutback Issues at a Data Center

By: IMCORP

Posted in: Workmanship, Facility

Pictured here are live front terminations of a medium voltage power cable system at a critical data center in Portland, OR.  After termination failures began to occur, DC HiPot testing had been utilized but came back inconclusive. At this po... Read Article

Power Cable Damage From Backfill

By: IMCORP

Posted in: Wind, Generation, Cable, Backfill

These images show a PD site in a medium voltage power cable, part of a collector system designed and installed at a wind farm in Idaho during 2005.  In the first few years of operation, the site experienced a very high collector syst... Read Article

Power Cable Termination Cutback Issues

By: IMCORP

Posted in: Wind, Generation

These pictures show two different live front substation terminal ends at a wind farm in Canada. The client believed that the medium voltage power cable termination ends at the substation were in fine working order. Also, external visual inspect... Read Article

Power Cable Insulation Damage (Sabotage) at a Wind Farm

By: IMCORP

Posted in: Workmanship, Generation, Cable

The discovery of this medium voltage power cable defect at a site in Canada provided an opportunity to demonstrate the effectiveness of IMCORP’s cable diagnostics. On a cable of over 1400 feet, IMCORP was able to locate the defect within si... Read Article