Insulator-Type-Tests.pdf
Transcript of Insulator-Type-Tests.pdf
-
7/28/2019 Insulator-Type-Tests.pdf
1/34
TYPE TESTS ON DISC INSULATOR
UNITS & STRINGS
-
7/28/2019 Insulator-Type-Tests.pdf
2/34
TYPE TESTS ON DISC INSULATOR
UNITS & STRINGS
On single units
Sl
no
Nature of test Reference: standard/document
1 Verification of dimensions Approved drawing
Disc diameter - do -
Unit spacing - do -
Creepage distance - do -
Radial & axial run out - do -
2 Thermal Mechanical
performance test
Powergrid tech specn & Cl 20 of IEC 383-
1/93
3 PF Voltage withstand and
flashover test (Dry & Wet)
Powergrid approved GTP & Cl 20 of IEC
383-1/93
4 LI withstand and flashover
test (Dry)
Powergrid approved GTP & Cl 20 of IEC
383-1/935 Visible discharge & RIV
test
Powergrid approved GTP, IS 731/71 &
IEC 437/97
6 R id l t th IEC 797
-
7/28/2019 Insulator-Type-Tests.pdf
3/34
On string with hardware fittings
Sl
no
Nature of test Reference: standard/document
1 PF voltage withstand
(Wet)
Cl 10 of IEC 383-2
2 SI voltage withstand
(Wet) - only on stringsused for 400 kV & above
Cl 11 of IEC 383-2
3 LI voltage withstand &
flashover test (Dry)
Cl 9 of IEC 383-2
4 Voltage distribution Powergrid tech specn
5 Mechanical strength test Powergrid tech specn
6 Vibration test Powergrid tech specn7 Power arc test IEC 1467
8 Artificial Pollution test
(only on anti fog discs)
IEC 507
-
7/28/2019 Insulator-Type-Tests.pdf
4/34
TYPE TEST PROCEDURE
TEST ON SINGLE UNITS
1) Verification of dimensions
Following physical dimensions shall be checked on 10 samples in
accordance with the drawing approved by Powergrid.
a) Disc diameter
b) Unit spacing
c) Creepage distance
d) Verification of eccentricitye) Gauge check of socket cap & Ball pin
Disc diameter
a) Reference standard Approved drawing
a) Purpose/critically oftesting
Influences the creepage distance of the single unit andalso gap between insulator strings in case of double,
triple & quad strings
b) Test procedure Check the outer diameter of disc & verify compliance
-
7/28/2019 Insulator-Type-Tests.pdf
5/34
Unit spacing
a) Reference standard Approved drawing
b) Purpose/critically of
testing
Influences the overall length of the string and hence the
phase to ground clearances.
c) Test procedure Check the ball pin to ball pin distance of the single unit
& verify compliance with the drawing
d) Acceptance criteria 120 kN 145 +/- 4 mm, 160 kN & 210 kN 170 +/- 5 mm.
e) Instruments used Marking block & vernier height gauge
-
7/28/2019 Insulator-Type-Tests.pdf
6/34
Creepage distance
a) Reference: standard Approved drawing
b) Purpose/critically of
testing
Influences the electrical performance especially under
pollution
c) Test procedure Using adhesive tape the shortest distance between thesocket cap & pin is measured accounting only the
porcelain surface.
d) Acceptance criteria Normal disc
120 kN 315 mm + 60/- 0
160 kN 330 mm + 40/- 0
Anti fog
120 kN 430 mm + 60/- 0
160 kN 475 mm + 40/- 0
e) Instruments used
Steel scale & adhesive tape
-
7/28/2019 Insulator-Type-Tests.pdf
7/34
Radial & axial run out
a) Reference standard Approved drawing
b) Purpose/critically of
testing
It is a measure of alignment of socket cap, porcelain and
ball pin. Influences the mechanical strength of the unit
c) Test procedure The insulator is placed under light tension between
suitably mounted coupling pieces. The two coupling pieces
shall be on the same axis and shall be free to rotate. Two
dial gauges are arranged as shown so that they make
contact with the maximum diameter and at the tip of the
outer most rib. The insulator is rotated through 360 deg
and the max variation in the readings of the dial gauges is
recorded.
d) Acceptance criteria Radial run out - < 3 % of disc dia
Axial run out - < 4 % of disc dia
e) Instruments used Dial gauge
-
7/28/2019 Insulator-Type-Tests.pdf
8/34
Gauge check for ball & socket coupling
a) Reference standard IEC 120
b) Purpose/critically of
testing
It is carried out to verify the compliance of the ball &
socket coupling with relevant gauges.
c) Test procedure The socket cap & ball pin of the insulator shall be
checked with the relevant standard calibrated GO &
NOT GO gauges. The samples shall comply with the
standard gauges.
d) Acceptance criteria Compliance with gaugese) Instruments used Standard Calibrated Gauges
-
7/28/2019 Insulator-Type-Tests.pdf
9/34
2) Thermal Mechanical performance test
a) Reference standard Powergrid tech specn &
Cl 20 of IEC 383-1/93
b) Purpose/critically of
testing
To check the mechanical performance of the samples
under simultaneous tensile loading and extreme varying
temperatures.c) Test procedure This test is carried out on 20 samples. The test is carried
out in a specially constructed thermal chamber. A tensile
load equal to 70 % of the specified EM load shall be
applied and the temperature inside the chamber shall be
varied from 30 deg to + 40 deg C in a duration of 24
hours. Minimum tensile load of 70 % shall be maintained
through out the 24 hours duration and shall be released
and reapplied after every 24 hours. After completing 4cycles of 24 hours each, the tensile load shall be released &
temperature brought down to the ambient and the units
shall be subjected to EMS test. No failure during thermal
cycles or during EMS test is permitted. After EMS test,
Average (X) & Standard deviation (S) is calculated &
statistically evaluated.
d) Acceptance criteria No failure during thermal cycles or during EMS test is
permitted. The test results shall meet the following
criteria.
X (R 3 ) h R i th t d EM t th
-
7/28/2019 Insulator-Type-Tests.pdf
10/34
TYPICAL LOAD & TEMPERATURE CURVE
-
7/28/2019 Insulator-Type-Tests.pdf
11/34
3) PF Voltage flashover & withstand test
Dry conditiona) Reference standard IEC 383-1
b) Purpose/critically oftesting
To verify the flashover & withstand voltage of the singleunit using PF voltage under dry condition
c) Test procedure The test is carried out on 3 samples. Voltage is applied to
the ball pin of the insulator & the socket cap is earthed. 5
flashovers are applied & average value obtained. The
voltage is reapplied and maintained at the specified value
for a duration of 1 minute & no flashover is permitted
during this interval.. The test values are corrected to the
standard atmospheric condition. The value obtained shall
be greater than the specified value
d) Acceptance criteria 120 kN F/o >75 kV, W/s >70 kV
160 kN F/o >80 kV, W/s > 75 kV
e) Instruments used PF testing transformer & arrangement for suspending the
insulator in vertical condition
Wet conditiona) Reference standard IEC 383-1
-
7/28/2019 Insulator-Type-Tests.pdf
12/34
4) Dry LI voltage flashover & withstand test
a) Reference standard IEC 383-1
b) Purpose/criticall
y of testing
To verify the flashover & withstand voltage of the
single unit using LI voltage under dry condition
c) Test procedure The test is carried out on 3 samples
d) Acceptance
criteria
120 kN 110 kV/120 kV
e) Instruments
used
Impulse Generator
5) Visible discharge & RIV test
a) Reference standard IEC 60-1 & 437
b) Purpose/critically
of testing
To verify the specified test voltage
c) Test procedure The test is carried out on 3 samples
d) Acceptance Visible Discharge voltage > 18 kV
-
7/28/2019 Insulator-Type-Tests.pdf
13/34
f) Residual strength test
a) Reference standard IEC 797
b) Purpose/critically of
testing
Verification of the minimum mechanical
strength of insulator stubs with out shed when
used in string.
c) Test procedure This test shall be carried out on 25 samples.
Samples shall be subjected to temperature cycle
test as per IEC 383-1. The sheds shall be broken
using hammer blows and no part of the broken
shed shall be greater than the maximum
diameter of the socket cap. The stubs shall then
be subjected to tensile load applied between themetal fittings and value recorded. Average (X)
& Standard deviation (S) of the test values shall
be calculated and compared with the factor k
(0.65)
d) Acceptance criteria (X 1.645 )/R 0.65
e) Instruments used Tensile testing machine
-
7/28/2019 Insulator-Type-Tests.pdf
14/34
g) Steep Front Wave test
b) Reference
standard
Powergrid technical specification
c) Purpose/critically
of testing
To verify the puncture withstand capability of
insulator in air when subjected to impulse voltage
of high rate of raise.
d) Test procedure This test is carried out on 10 samples. Each
insulator shall be subjected to 5 positive & 5
negative impulses with effective rate of raise of
2500 kV/micro sec. Subsequently the samples shall
be subjected to PF flashover test under Dry
condition.
e) Acceptance
criteria
Average of 3 PF flashovers shall not be lesser than
95 % of the specified Dry PF flashover voltage. No
puncture shall occur either during Impulse or PF
voltage application
f) Instruments used LI generator, PF test transformer
-
7/28/2019 Insulator-Type-Tests.pdf
15/34
Typical wave shape
Calculation of steepness
Steepness = Voltage/Raise time
Voltage = Y x Voltage scale x divider ratio x attenuation
-
7/28/2019 Insulator-Type-Tests.pdf
16/34
h) Impact test
i) Reference
standard
Powergrid tech specn & ANSI C 29.2
j) Purpose/critically
of testing
To verify the withstand capability of insulator
shed when subjected to mechanical impact.
k) Test procedure 3 samples shall be subjected to specified Impact
load applied to the outer most rim of the
insulator. No breakage of the insulator shed is
permitted. Subsequently the samples shall also
pass PF frequent flashover test. No puncture shall
occur during flashover test.
l) Acceptance
criteria
7 N-m for up to 120 kN. 10N-m for above 160 kN
disc insulators
m)Instruments used Impact testing machine & PF test transformer
-
7/28/2019 Insulator-Type-Tests.pdf
17/34
TEST ON STRINGS WITH HARDWARE FITTINGS
-
7/28/2019 Insulator-Type-Tests.pdf
18/34
a. PF voltage withstand (Wet)
a) Reference standard Cl 10 of IEC 383-2
b) Purpose/critically
of testing
To verify the specified withstand voltage of the
insulator string
c) Test procedure In accordance with IEC
d) Acceptance
criteria
220 kV 460 kV, 400 kV - 680 kV
e) Instruments used PF Testing transformer
b. SI voltage withstand (Wet)
a) Reference standard Cl 11 of IEC 383-2
b) Purpose/critically
of testing
To verify the specified withstand voltage of the
insulator string under wet condition
c) Test procedure In accordance with IEC
-
7/28/2019 Insulator-Type-Tests.pdf
19/34
e) Instruments used Impulse Generator
d. Voltage distribution (Dry)
a) Reference standard Powergrid tech specn
b) Purpose/critically
of testing
To measure the distribution of voltage across an
energized disc insulator string
c) Test procedure Sphere gap method, % VD = E/Vn x 100
d) Acceptance
criteria
400 kV < 10 %
e) Instruments used PF Testing transformer, Calibrated spheres
-
7/28/2019 Insulator-Type-Tests.pdf
20/34
-
7/28/2019 Insulator-Type-Tests.pdf
21/34
e. Radio Interference Voltage test
a) Reference standard Powergrid tech specn
b) Purpose/critically
of testing
To measure the Radio noise generated by the test
sample when subjected to HV stress.
c) Test procedure IEC 60437
d) Acceptance
criteria
Noise level < 60 dB @ 305 kV for 400 kV strings
e) Instruments used PF Testing transformer, Coupling capacitor,
Radio noise meter
f. Corona test
a) Reference standard Powergrid tech specn
b) Purpose/critically
of testing
To measure the Corona Inception & extinction
voltage on the test sample
c) Test procedure IS 731-1971
d) Acceptancecriteria
Extinction voltage > 320 kV for 400 kV strings
e) Instruments used PF Testing transformer, dark test hall
-
7/28/2019 Insulator-Type-Tests.pdf
22/34
-
7/28/2019 Insulator-Type-Tests.pdf
23/34
h. Vibration test
a) Reference standard Powergrid tech specn
b) Purpose/critically
of testing
To verify the performance of the insulator set
under Dynamic loading
c) Test procedure Powergrid spec
d) Acceptance
criteria
Shall withstand 10 million cycles of vibration
under specified conditions
e) Instruments used Vibration inducing equipment
-
7/28/2019 Insulator-Type-Tests.pdf
24/34
-
7/28/2019 Insulator-Type-Tests.pdf
25/34
-
7/28/2019 Insulator-Type-Tests.pdf
26/34
-
7/28/2019 Insulator-Type-Tests.pdf
27/34
i. Power Arc test
a) Reference standard IEC 1467
b) Purpose/critically
of testing
To verify the performance of the insulator set
when subjected to Power Arcs
c) Test procedure IEC 1467
d) Acceptance
criteria
The string shall not separate after subjected to 3
shots of 40 kA for a duration of 0.2 s, 0.2 s & 0.5 s.
Subsequently the string shall withstand 80 % of
the rated tensile load
e) Instruments used Short circuit generator
-
7/28/2019 Insulator-Type-Tests.pdf
28/34
-
7/28/2019 Insulator-Type-Tests.pdf
29/34
-
7/28/2019 Insulator-Type-Tests.pdf
30/34
j. Artificial Pollution withstand test
a) Reference standard IEC 507
b) Purpose/critically
of testing
To verify the performance of the insulators under
polluted condition
c) Test procedure IEC 507, Salt fog Method & Clean fog method
d) Acceptance
criteria
The string shall withstand 3 voltage applications
at specified Pollution level & testing conditions
e) Instruments used PF testing transformer, Pollution chamber
-
7/28/2019 Insulator-Type-Tests.pdf
31/34
-
7/28/2019 Insulator-Type-Tests.pdf
32/34
-
7/28/2019 Insulator-Type-Tests.pdf
33/34
-
7/28/2019 Insulator-Type-Tests.pdf
34/34