ASTM D6180-98

Standard Test Method for Stability of Insulating Oils of Petroleum Origin Under Electrical Discharge

SCOPE
1.1 This test method covers a laboratory technique that measures the stability of new, used, or reclaimed insulating oils, similar to those described in Specification D 3487 in the presence of a controlled electric discharge. When subjected to this type of discharge, insulating oils absorb energy and produce gases as well as ionized molecules (charge carriers). The quantity of these decay products can be measured and can provide an indication of the stability of oils under the conditions of this test.

General Information

• Status: Historical
• Publication Date: 09-Oct-1998
• ICS: 29.040.10 - Insulating oils
• Technical Committee: D27 - Electrical Insulating Liquids and Gases
• Drafting Committee: D27.05 - Electrical Test

Relations

• Replaced By: ASTM D6180-98(2004) - Standard Test Method for Stability of Insulating Oils of Petroleum Origin Under Electrical Discharge
• Effective Date: 01-Oct-2004

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D6180–98
Standard Test Method for
Stability of Insulating Oils of Petroleum Origin Under
Electrical Discharge
This standard is issued under the fixed designation D 6180; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Summary of Test Method
1.1 This test method covers a laboratory technique that 3.1 A test specimen is introduced into a discharge cell and
measures the stability of new, used, or reclaimed insulating degassed under vacuum at room temperature. An ac potential
oils, similar to those described in Specification D 3487 in the of 10 kV is applied between a high voltage electrode and a
presence of a controlled electric discharge. When subjected to grounded salt water electrode for 300 min. The gradual rise of
this type of discharge, insulating oils absorb energy and the pressure inside the discharge cell is measured on an
produce gases as well as ionized molecules (charge carriers). electronic vacuum meter as a function of time. The dissipation
The quantity of these decay products can be measured and can factor of the oil at 100°C is determined before and after the
provide an indication of the stability of oils under the condi- stability test.
tions of this test.
4. Significance and Use
1.2 The gases are retained in the discharge cell and their
pressure measured. The charge carriers remain in the test 4.1 During this test, insulating oil in an evacuated cell is
subjected to a high voltage discharge between two electrodes.
specimen. The change in the dissipation factor before and after
the discharge is determined. The discharge generates free electrons. These electrons collide
with the oil molecules causing many of them to become
1.3 The values stated in SI units are to be regarded as the
standard. The values stated in parentheses are for information electronically excited. Some of these molecules lose this
energyasaquantaoflightemittingfluorescentradiation.Some
only.
1.4 This standard does not purport to address all of the of the other excited molecules decompose into gases, ionized
molecules and free radicals. These changes can provide an
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- indication of the stability of oils under the conditions of this
test method. The measures of these changes are the increase of
priate safety and health practices and determine the applica-
the pressure in the test cell and the increase in the dissipation
bility of regulatory limitations prior to use. Specific cautionary
statements are given in 5.3 and 7.1. factor of the test specimen.
4.2 During the test, the gas content increases in the cell and
2. Referenced Documents
the concentration of charge carriers increases in the oil.
2.1 ASTM Standards:
2 5. Apparatus
D 923 Practice for Sampling Electrical Insulating Liquids
D 924 TestMethodforDissipationFactor(orPowerFactor) 5.1 Discharge Cell, shown in Fig. 1, includes an electronic
vacuummeter.Thecellmustbemadeofquartz,beofspherical
and Relative Permittivity (Dielectric Constant) of Electri-
cal Insulating Liquids shape, and have a 500 mL capacity. The electrode is sealed in
the cell as shown in Fig. 1. The free electrons are generated by
D 3487 Specification for Mineral Insulating Oil Used in
Electrical Apparatus a cylindrical copper electrode 15 mm (0.6 in.) in diameter and
10 mm (0.4–in.) long, which is placed in the center of the
2.2 IEEE Standard:
4–1995 IEEE Standard Techniques for High-Voltage Test- discharge cell.
5.2 Glass Dish, approximately 150 mm (6 in.) in diameter
ing
and 100 mm (4 in.) deep for holding a salt-water ground
electrode.
This test method is under the jurisdiction of ASTM Committee D27 on
5.3 Test Chamber, with safety interlocked door, which
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
deenergizesthetesttransformerwhenopenedandlargeenough
mittee D27.05 on Electrical Test.
Current edition approved Oct. 10, 1998. Published January 1999. Originally
published as D 6180-97. Last previous edition D 6180-97.
Annual Book of ASTM Standards, Vol 10.03.
3 4
Available from the Institute of Electrical and Electronic Engineers, Inc., P.O. Asuitable discharge cell is obtainable from Insoil Canada Ltd., 231 Hampshire
Box 1331, Piscataway, NJ 08855. Place, N.W., Calgary, AB Canada T3A 4Y7.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
D6180–98
FIG. 1 Discharge Cell
to contain the desired number of cells with at least 100 mm (4 5.8.3 A voltmeter connected to the low voltage side of the
in.) clearance between cells, sides, and top. testing transformer if the measurement error can be maintained
5.4 Power Source Step-Up Transformer, 60 Hz, 200 VA, within the limit specified in 5.9.
115 or 230 V to at least 10 kV. Design the transformer of such 5.9 Accuracy—Thecombinedaccuracyofthevoltmeterand
a size that, with the test specimen in the circuit, the voltage voltage measuring circuit should be such that the measurement
waveshape is approximately a sinusoid with both half cycles error does not exceed 5 %, calibrated by means of a recom-
alike, and it should have a ratio of peak-to-rms value equal to mended method in IEEE Standard No. 4.
the 2 65%. 5.10 Vacuum Pump, laboratory-type capable of attaining a
=
5.5 Variable-Tap Autotransformer or Equivalent, 200 VA vacuum of less than 100 Pa.
min, 115 or 230 V for applying voltage to transformer. 5.11 Clamp Stand, for supporting cell in chamber.
5.6 Relay, 115 or 230 V, double-pole, for energizing trans- 5.12 Vacuum Gage, Electronic vacuum meter.
former.
5.7 Switch, double-pole, 115 or 230 V, on-off switch for
6. Sampling
applying voltage to circuit.
6.1 Insulating oils for this test should be sampled in accor-
5.8 Voltmeter—Measure the voltage by a method that ful-
dance with Test Method D 923.
fills the requirements of IEEE Standard No. 4 , giving rms
values, preferably by means of:
7. Cleaning Test Cell
5.8.1 A voltmeter connected to the secondary of a separate
7.1 Before using the cell, it should be thoroughly flushed
potential transformer, or
out with suitable solvent such as petroleum ether or heptane.
5.8.2 Avoltmeter connected to a well-designed tertiary coil
in the test transformer, or NOTE 1—Caution: Solvents should be used under a ventilated hood.
D6180–98
Deposits that are not removed by solvent cleaning may 8.8 Measure the pressure inside the discharge cell in Pa by
accumulate on the side of the flask. If this occurs, the deposit reading the electronic vacuum meter to obtain a measure of the
should be removed by mechanical means, using a strong quantity of gases evolved.
detergent and brush to ensure that the cell is free of all 8.9 Remove the test specimen from the cell and determine
impurities. its dissipation factor at 100°C.
7.2 The electrode also should be free of liquid dielectric or
9. Report
solid deposits which may be accumulated on its surface. This
can be done using very fine sand paper followed by wiping the
9.1 Report the following information:
surfacewithfilterpapertoremoveanyresidualsandpapergrit.
9.1.1 Initial pressure of the Discharge Cell at beginning of
Finally,rinsethecellwithdistilledwate
...