C37.41 WGPolymer Cutout Task Force

Frank C. Lambert, P.E.September 22, 2015

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Noticea. The material contained herein is, to our knowledge, accurate and reliable at the date of publication. b. It is provided for the overall benefit of the electric energy delivery industry.c. It shall not be construed as an endorsement of any project, process or provider by the Georgia Tech Research Corporation (GTRC), the Georgia Institute of Technology (GIT) or NEETRAC.d. Neither GTRC nor GIT nor NEETRAC shall be responsible for any injury to or death of persons or damage to or destruction of property or for any other loss, damage or injury of any kind whatsoever resulting from the use of the project results and/or data. e. GTRC, GIT and NEETRAC disclaim any and all warranties, both express and implied, with respect to analysis or research or results contained in this material.f. It is the user's responsibility to conduct the necessary assessments in order to satisfy themselves as to the suitability of the products or recommendations provided in this material. g. Title to the information herein shall reside with GTRC.

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Polymer Cutout ManufacturersParticipation from:ABB, Advanced Rubber Products, Aluma‐Form, Eaton’s Cooper Power Systems, Hubbell Power Systems, MacLean Power Systems, Powerline Hardware and Utility Solutions

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Anonymous Data• Only manufacturers of cutouts will have access to their own results, if they so elect. All other NEETRAC members (both utilities and manufacturers) will only have access to generic data.

• NEETRAC Member cutout manufacturers (ABB, Aluma‐Form, Eaton’s Cooper Power Systems, Hubbell and MacLean) will have the right to share their results as per standard NEETRAC baseline policy.

• Non‐member manufacturers (ARP, PLH and Utility Solutions) will have access to their own results for Internal Use only. They will not have the right to share their results with NEETRAC utilities.

• NEETRAC will present generic results to Polymer Insulator TF of C37.41 after review by Technical Advisors.

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Test 1 ‐Mechanical Endurance at Temperature Extremes (18.1.1)

5

Heat Rise Test

6

18.1.1.3 Test procedureFour complete temperature cycles shall be performed on the three samples. The procedure for each sample shall be as follows:a) The samples shall be placed in an environmental chamber capable

of operating between -30˚C (+/-5 ˚C) and +40˚C (+/-5˚C).b) The samples shall be initially lowered in temperature from room

temperature to -30˚C. The samples shall be allowed to soak at -30˚C for a minimum of 8 hours.

c) The temperature of the chamber shall then be increased from -30˚C to +40˚C and again allowed to soak for a minimum of 8 hours.

d) The temperature of the chamber shall then be decreased to room temperature to end the cycle and re-set for the beginning of the next cycle.

e) The temperature ramp rates shall be specified by the manufacturer in order to minimize the possibility of thermal shock while still allowing time for 8 hour soak periods at each temperature extreme.

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18.1.1.3 Test proceduref) Once per cycle, a series of 50 mechanical Open-Close operations

shall be performed on each sample. Twenty five Open-Close operations shall be performed on each side at a minimum angle of 30 degrees offset from center. The operations shall be performed when the assemblies are at the temperature extremes and the operations should alternate between the temperatures such that a total of 100 operations are performed at -30˚C and 100 operations are performed at +40˚C.

g) Opening operations shall be performed using a Loadbreak Tool or whatever device is recommended by the manufacturer for opening the sample under load. Closing operations may be performed with a hot stick or any other device recommended by the manufacturer.

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18.1.1.4.1 GeneralThe following acceptance criteria shall be applied:a) The condition of the samples shall be as specified in 7.8. b) There shall be no loose or deformed parts, cracks or other obvious signs of

visual deformation. c) The overall length of the fuse supports shall be measured following the four

cycles and confirmed to comply with manufacturer’s requirements. d) Each sample shall be subjected to a temperature rise test at rated continuous

current of the fuse support and fuse unit, whichever is lower. The samples shall demonstrate thermal stability without thermal runaway occurring. The temperature rise of individual components may exceed the temperature rise limits in 5.2.9, provided that all thermocouples demonstrate that temperature stability has occurred

e) The samples shall demonstrate that they remain capable of full mechanical function following the four temperature cycles. In order to verify performance, the samples shall be subjected to a low voltage source current sufficient to melt the fusible element. It shall be verified that the fusible element melts and that the fuse unit travels to its appropriate open state.

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18.1.1.4.2 Dye penetration testAfter the testing detailed in 18.1.1, a dye penetration test shall be performed on the core material in order to verify that no damage to the core material occurred during the mechanical tests. The dye penetration test procedure and criteria for acceptance shall be as follows: a) Five samples shall be cut from the tested insulators The length of the samples

shall be 10mm +/-1mm b) The samples shall be cut 90 degrees to the axis of the core. The cut ends shall

be free of any discoloration resulting from burning or scorching during the cutting or sanding process. The cut surfaces shall be smoothed with a 180-grit abrasive cloth.

c) The samples shall be placed on a layer of steel or glass balls of uniform diameter in a glass vessel with one of the cut ends sitting on the balls.

d) Dye composed of 1 gram of Fuchsin in 100 grams of Methanol shall be poured into the vessel until its level is 2mm to 3mm above the top of the balls.

e) Once the dye is poured, wait 15 minutes and examine the samples. If no dye has risen through the samples by capillarity after 15 minutes, the test is considered to have passed.

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Mechanical Endurance Results (18.1.1)Manufacturer Mechanical

Operation Heat Rise Fuse Operation DyePenetration

Anon

ymou

s

P P P P

P P P P

P P P P

P P P P

P P P P

P P F P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

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Mechanical Endurance Results (18.1.1)

Manufacturer MechanicalOperation Heat Rise Fuse Operation Dye

PenetrationAn

onym

ous

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

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Test 2 ‐ Long Term Deformation / Creep (18.1.2)Trial procedure has two technicians performing five contact path distance measurements on each sample for initial, 8, 24 and 168 hour measurements.

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Test 2 ‐ Long Term Deformation / Creep (18.1.2)

a) Place three samples and fuse tubes (removed) in thermal chamber at 75 °C and leave overnight.

b) The following morning, install fuse tubes, return samples to the chamber and start clock.

c) Remove one sample at each of the following times: 8 hours, 24 hours, and 168 hours from start time (removal times chosen to facilitate employee availability)

d) Immediately submerge in room temperature water for 1 minute.e) Remove the sample from the water tank and begin measurements (2

technicians, 5 measurements each).f) Let samples sit for 24 hours, then repeat measurements (2 technicians, 5

measurements each).g) Analyze data

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Long Term Deformation / Creep Results (18.1.2)

180160140120100806040200

0.05

0.04

0.03

0.02

0.01

0.00

Hour

Del

ta

12345678

Mfg

Scatterplot of Delta vs Hour

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‐0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

MFG

MFG

MFG

MFG

MFG

MFG

MFG

MFG

Delta

(Inche

s)

Long Term Deformation / Creep Results (18.1.2)

8 24

168

8 24

168

8 24

168

8 24

168

8 24

168

8 24

168

8 24

168

8 24

168

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Differences in individual samples were greater out of the box than changes observed in LTD tests.

None of the samples exhibited any evidence of Long Term Creep.

Manufacturer Min to max for three samplesAn

onym

ous

0.023”

0.046”

0.022”

0.092”

0.188”

0.108”

0.055”

0.034”

Long Term Deformation / Creep Results (18.1.2)

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Test 3 ‐ Accelerated Weathering (18.2.2)

• UVB bulbs• 4 hr. UV at 60˚C, cycled

with…• 0.25 hr. Water spray / 3.75 hr.

Condensation at 50˚C• 2000 hours, inspected at 250

hour intervals (color, integrity, etc.)

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18.2.2.2 Test setupEach sample shall be tested for a duration of 1000 hours UVB light. The cycles shall consist of four hours exposure to UVB light at 60 °C followed by 0.25 hours water spray and 3.75 hours condensation at 50 °C. The test shall continue until 2000 total test hours (250 cycles) have accumulated. Every 250 hours, the test samples may be inspected and checked for signs of degradation of color and material integrity.18.2.2.3 Acceptance criteriaSamples shall be considered to have passed the test if the surface remains free of defects including: cracks (damage exposing the subsurface), blisters (visual surface projections), or crumbling (material removal from bulk material). All identification marks on the exterior of the insulator shall also remain visible following the test. In addition, a power frequency dry withstand test shall be performed on each sample with success determined by the ability of each sample to withstand its power frequency dry withstand rating.

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Accelerated Weathering Results (18.2.2)

Manufacturer Defects /Blisters

Cracks / Crumbling

ID Marks Visible

Dry AC Withstand

Anon

ymou

s

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

Note: Only one sample of each manufacturer was evaluated in this test program. The standard will require each design to have three units tested.

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Test 4 ‐ Tracking and Erosion (18.2.3)

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18.2.3.2 Test Procedurea) The test samples shall be energized at a voltage no less than 58% of the

device’s maximum rated voltage (equivalent to the line‐to‐ground voltage of a grounded wye system).

b) The test circuit shall be configured such that no more than a maximum voltage drop of 5% occurs when the circuit is loaded with a resistive current of 250mA (r.m.s.) on the high voltage side.

c) The test may be interrupted for a maintenance period of up to 8 hours with the cycle remaining valid. Maintenance time shall not be included in the cumulative test time.

d) The saline solution in the tank shall consist of de‐ionized water with 1.40 ±0.06g/l of NaCl.

e) Each sample shall be exposed to 30,000 cycles.f) Each cycle shall consist of the insulator going through the four positions

shown in Figure XX. Cycle time shall be 200 sec ± 25 sec. with the insulator stationary no less than 80% of the cycle time. Each position shall require an approximately equal period of time.

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g) After every four days of testing, the samples shall be given a 24 hour recovery period. During this period, the test procedure remains unchanged except that the saline solution is removed from the dip tank.

18.2.3.3 Acceptance CriteriaEach aged sample is acceptable if all 30,000 cycles are completed without the test circuit tripping out due to high leakage currents. In addition, for composite polymer insulators, there shall be no tracking or erosion to the core and no shed or housing puncture that exposes the core rod.

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Once the samples are removed from the tracking wheel and are no longer going through dip cycles, each aged sample and the reference sample shall be tested and evaluated to the following tests, which must be completed within 48 hours. The samples shall be rinsed in de‐ionized water prior to the following tests. The tests shall be performed in the order listed:a) Each sample shall undergo a Mega‐Ohm meter resistance test. The minimum

test voltage shall be 1kV. Measurements shall be made between the two end fittings and between each end fitting and the center fitting. The resistance shall be at least 3MΩ for all tests.

b) Steep‐front impulse voltage test detailed in 18.3.3 Clauses e‐h. Pre‐boiling the tested samples is NOT required. Samples are considered to have passed the test if no punctures occur that expose the core rod (composite polymer insulator) or any potted fittings (resin polymer insulator).

c) Lightning Impulse Withstand Test. Each tested sample must be able to successfully pass a Lightning Impulse Withstand test at 80% of its rating.

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Tracking and Erosion Results (18.2.3)

Manufacturer Core Exposed Mega‐Ohm Steep‐front 80% BILAn

onym

ous

P P P P

P P P P

P P F P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

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Tracking and Erosion Results (18.2.3)Manufacturer Core Exposed Mega‐Ohm Steep‐front 80% BIL

Anon

ymou

s

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

P P P P

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Tracking and Erosion Results (18.2.3)

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Steep-Front Puncture Locations

Test 5 ‐Water Penetration Tests (18.3)

Submersion Tank (100˚C)28

Steep-front Generator29

ac Tests

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18.3.3 Test Procedurea) The hardness of the insulator outer housing material on each sample shall be measured in accordance with ASTM D2240 with a Shore A durometer.

b) Each sample shall be boiled for 100 hours in water having .1% by weight of NaCl.

c) At the end of the boiling process, each sample shall be rinsed with deionized water and the hardness re‐measured. The hardness of the outer housings shall not have changed by more than 20%.

d) The tests described in e) through h) shall be completed within 48 hours of the samples being removed from the boiling water.

e) Each sample shall be subjected to ten positive and ten negative impulses of at least 1000 kV/s in accordance with IEEE Standard 4‐2013, Clause 8.1, see “linearly rising front chopped impulse”. For the steep‐front impulse test, the samples shall be mounted per the manufacturer’s specification with fuse tubes or fuse units installed in the fuse support. The steep‐front impulse test is considered acceptable if no punctures that expose the core rod occur.

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f) Each sample shall be subjected to an elevated AC withstand flashover test. The dry power frequency average flashover voltage shall be determined by averaging five flashover voltages on each sample.

g) Using the same method specified in item f), the value of the reference flashover voltage shall be determined using an additional reference sample. The samples and the reference sample shall then be continuously subjected to 80% of the average flashover voltage of the reference sample for 30 minutes.

h) The temperature of the housing between the sheds of each sample and of the reference sample shall be measured at three different places along the length of the insulator immediately after removal of the test voltage.

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18.3.4 Acceptance Criteriaa) The average flashover voltage of each sample shall be greater than

or equal to 90% of the average reference flashover voltage.b) No puncture on any part of the sample shall occur during the AC

withstand tests. c) The maximum temperature rise of each sample’s housing, between

the sheds with respect to the temperature of the reference sample, shall be less than 10˚C.

Note: Results are shown in the following two slides for all post boiling metrics (Hardness, Steep Front, AC Flashover and AC Withstand) for the purpose of evaluating the proposed standard. Normally the tests would be terminated after the first failure. Steep front punctures are shown as PC if over or near center pin, PE if over or near end fitting and PI if there is no external puncture.

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Water Penetration Results (18.3)Manufacturer Hardness Steep

FrontAC Flashover90% of Ref Vf

AC Withstand80% of Ref Vf

Anon

ymou

sP PE P P

P P P P

P F P F

P PC F F

P P P P

P P P P

P PI F F

P P P P

P P P P

P F F F

P PI F F

P P P P

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Water Penetration Results (18.3)Manufacturer Hardness Steep Front AC Flashover

90% of Ref Vf

AC Withstand80% of Ref Vf

Anon

ymou

sP F F F

P P P P

P P P P

P P P P

P P P P

P P P P

P F F F

P PC F F

P F F F

P P P P

P F F F

P F F F

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36

Steep-Front Puncture Locations

37

Steep-Front Puncture Locations

Test 6 ‐ Interrupting Tests at Temperature Extremes (18.4 )

18.4.2 Number of devices to be testedAt least one complete sample shall be tested at each temperature extreme, one sample at ‐30°C (+/ 3°C) and one sample at 40°C (+/ 3°C). The samples shall be tested to the circuit parameters, procedures and acceptance criteria defined in Table 4, Test Series 1 except that only the minimum fuse link size specified in Table 4 for Test Series 1 shall be required to be tested 18.4.3 Sample preparationThe test samples are to be placed in an environmental chamber, oven or freezer and heated or cooled to the specified temperature. If the device is moved from the controlled temperature for testing in a power test laboratory, the temperature of the device may need to be initially hotter or cooler than the specified temperature to allow for the moderation of the temperature during movement, installation and testing. This means that the samples must be at the specified temperature at the time the interrupting test is conducted.

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In monitoring the temperature of the samples under test a reference sample can be used. The temperature for a composite polymer insulator shall be measured at its core. The temperature for a resin polymer insulator shall be measured +/‐.25 inches from the center of the insulator trunk.The reference insulator is to be identical to the insulator used in the sample to be tested. Thermocouples are added to the reference insulator as required for the type of insulator. Once the test sample and the reference sample reach the agreed upon temperature, both are moved. The temperature of the reference sample shall be measured during movement and installation of the test sample into the test fixtures to verify that the device under test is at the specified temperature at the time if test. Since the devices are the same, the temperature of each can also be assumed to be the same.NOTE— Other methods are permissible for verifying that sample temperatures are at the values required are for acceptance. The test laboratory shall document the means by which the temperatures were verified in the test report.

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18.4.4 Interrupting test procedureFollowing the initial test, which may be performed at either temperature extreme, the test sample shall be reassembled with a new fuse link or fuse unit. The complete assembly under test, along with the reference sample shall be heated or cooled to the required temperature.

Prior to each interrupting operation, the test samples shall remain in the environmental chamber, oven or freezer until the reference insulator is at the required temperature. At that point the samples will be moved to the test cell and the interrupting test completed. 18.4.5 Acceptance criteriaa) All tests must result in successful interruption with the sample properly operating to its open state. There shall be no visible damage to the fuse support and insulator.

b) The samples from each tested insulator shall be subjected to a Dye Penetration Test as defined in Clause 18.1.1.4.2

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Temp 0 Time Temp 90 Time Temp 140 Time TempC P 4:01 -32.2 P 3:48 -31.8 P 3:30 -29.0C P 4:37 -22.0 P 4:38 -26.3 P 3;34 -27.9C P 4:38 -26.0 P 4:41 -27.0 P 3:19 -27.5C P 4:09 -29.3 P 3:20 -30.3 P 3:25 -25.8C P 4:51 -28.6 P 3:25 -32.0 P 3:35 -31.5C P 3:25 -28.7 P 4:02 -26.2 P 3:37 -27.5C F 3:55 -29.8C F 4:32 -28.7

Average 4:16 -28.2Min 3:25 -32.2Max 4:51 -22.0

H P 4:22 40.7 P 3:32 41.2 P 3:22 41.5H P 3:15 40.6 P 3:40 42.1 P 4:50 40.7H P 5:35 40.2 P 3:33 40.6 P 3:33 40.5H P 3:32 42.4 P 2:58 43.1 P 2:59 41.2H P 3:13 41.3 P 3:29 41.6 P 3:30 41.1H F 3:16 42.0H F 3:28 40.1H F 3:25 40.8

Average 3:45 41.0Min 3:13 40.1Max 5:35 42.4

Interruption at Temperature Extremes (18.4)

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Interruption at Temperature Extremes (18.4)

Manufacturer InterruptionHot

InterruptionCold Dye Penetration

Anon

ymou

sP P P

P P P

P P P

P P P

P P P

F P P

F F P

F F P

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