ASTM D877/D877M-19

Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes

SIGNIFICANCE AND USE
3.1 The dielectric breakdown voltage is a measure of the ability of an insulating liquid to withstand electrical stress. The power-frequency breakdown voltage of a liquid is reduced by the presence of contaminants such as cellulosic fibers, conducting particles, dirt, and water. A low result in this test method indicates the presence of significant concentrations of one or more of these contaminants in the liquid tested. See Appendix X1.  
3.2 A high breakdown voltage measured in this test method does not necessarily indicate that the amount of the contaminants present in a liquid from which the sample was taken is sufficiently low for the sampled liquid to be acceptable in all electrical equipment. Test Method D877 is not sensitive to low levels of these contaminants. Breakdown in this test method is dominated by events occurring at the electrode edges. The voltage stress distribution between the parallel disk electrodes used in this test method are quasi-uniform and there is substantial stress concentration at the sharp edges of the flat disk faces.  
3.3 This test method may be used for evaluation of insulating liquids in equipment that is designed to be filled with unprocessed liquids as delivered by a vendor.  
3.4 This test method is not recommended for evaluation of the breakdown voltage of liquids used in equipment that requires the application of vacuum and filtering of the oil before being placed into service. Test Method D1816 should be used to determine the breakdown voltage of filtered and degassed liquids.  
3.5 This test method is used in laboratory or field tests. For field breakdown results to be comparable to laboratory results, all criteria including room temperature (20 to 30 °C) must be met.
SCOPE
1.1 This test method describes two procedures, A and B, for determining the electrical breakdown voltage of insulating liquid specimens. The breakdown test uses ac voltage in the power-frequency range from 45 to 65 Hz.  
1.2 This test method is used to determine the electrical discharge voltage of in-use electrical liquids. It is no longer applicable to new insulating liquids upon receipt, in which case Test Method D1816 shall be used.
Note 1: It is understood that long-term histories for this test method exist, but this test method is no longer considered applicable as numerous deficits exist that affect its usefulness. It is recommended to move all new and in-service electrical discharge voltage testing of electrical insulating liquids to Test Method D1816.  
1.3 Limitations of the Procedures:  
1.3.1 The sensitivity of this test method to the general population of contaminants present in a liquid sample decreases as applied test voltages used in this test method become greater than approximately 25 kV rms.  
1.3.2 If the concentration of water in the sample at room temperature is less than 60 % of saturation, the sensitivity of this test method to the presence of water is decreased. For further information refer to RR:D27-1006.2  
1.3.3 The suitability for this test method has not been determined for a liquid's viscosity higher than 900 cSt at 40 °C.  
1.4 Procedure Applications  
1.4.1 Procedure A:  
1.4.1.1 Procedure A is used to determine the breakdown voltage of liquids in which any insoluble breakdown products easily settle during the interval between the required repeated breakdown tests. These liquids include petroleum oils, hydrocarbons, natural and synthetic esters, and askarels (PCB) used as insulating and cooling liquids in transformers, cables, and similar apparatus.
1.4.1.2 Procedure A may be used to obtain the dielectric breakdown of silicone fluid as specified in Test Methods D2225, provided the discharge energy into the sample is less than 20 mJ (milli joule) per breakdown for five consecutive breakdowns.  
1.4.2 Procedure B:  
1.4.2.1 This procedure is used to determine the breakdown voltage of liquids in which any insoluble breakdown pro...

General Information

• Status: Published
• Publication Date: 30-Nov-2019
• ICS: 29.040.10 - Insulating oils
• Technical Committee: D27 - Electrical Insulating Liquids and Gases
• Drafting Committee: D27.05 - Electrical Test

Relations

• Replaces: ASTM D877/D877M-13 - Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes
• Effective Date: 01-Dec-2019
• Refers: ASTM D923-15(2023) - Standard Practices for Sampling Electrical Insulating Liquids
• Effective Date: 01-Dec-2023
• Refers: ASTM D1816-12(2019) - Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using VDE Electrodes
• Effective Date: 01-Oct-2019
• Refers: ASTM D2864-17a - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 01-Mar-2017
• Refers: ASTM D2864-17 - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 01-Feb-2017
• Refers: ASTM D923-15 - Standard Practices for Sampling Electrical Insulating Liquids
• Effective Date: 01-Oct-2015
• Refers: ASTM D2864-10 - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 15-May-2010
• Refers: ASTM D2864-10e1 - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 15-May-2010
• Refers: ASTM D2864-09 - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 01-Jan-2009
• Refers: ASTM D923-07 - Standard Practices for Sampling Electrical Insulating Liquids
• Effective Date: 15-Jul-2007
• Refers: ASTM D2864-07 - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 01-Jul-2007
• Refers: ASTM D2864-06 - Standard Terminology Relating to Electrical Insulating Liquids and Gases
• Effective Date: 15-Jun-2006
• Refers: ASTM D2225-04 - Standard Test Methods for Silicone Fluids Used for Electrical Insulation
• Effective Date: 01-Dec-2004
• Refers: ASTM D1816-04 - Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Using VDE Electrodes
• Effective Date: 01-Feb-2004
• Refers: ASTM D1816-03 - Standard Test Method for Dielectric Breakdown Voltage of Insulating Oils of Petroleum Origin Using VDE Electrodes
• Effective Date: 01-Oct-2003

Overview

ASTM D877/D877M-19 is the internationally recognized standard test method for determining the dielectric breakdown voltage of electrical insulating liquids using disk electrodes. Developed by ASTM International, this procedure plays a critical role in evaluating the ability of insulating liquids-such as transformer oils and other electrical fluids-to withstand electrical stress and ensure the reliable operation of electrical equipment. The method is widely used for both laboratory and field testing, focusing primarily on unprocessed liquids as delivered by a vendor.

Key Topics

• Dielectric Breakdown Voltage: This is the primary parameter assessed, reflecting the liquid's resistance to electrical discharge under power-frequency AC voltages (45–65 Hz). Results highlight the effect of contaminants like water, dirt, fibers, or conductive particles.
• Testing Procedures (A and B):
  • Procedure A is suitable for clean liquids where breakdown products settle quickly (e.g., petroleum oils, esters, silicone fluids under certain limits).
  • Procedure B is intended for liquids with insoluble breakdown products that do not settle rapidly, commonly used for contaminated or in-use fluids from field samples.
• Sample Preparation and Equipment: Consistency in gap spacing, electrode preparation, and strict cleaning protocols are essential for accurate results.
• Sensitivity and Limitations: The method is less sensitive at higher voltages (>25 kV rms) and with liquids having low water content; not recommended for filtered or degassed liquids, where ASTM D1816 is preferred.
• Significance of Results: Low breakdown voltage indicates contamination, while high results do not necessarily confirm suitability for all applications due to low sensitivity at trace contaminant levels.

Applications

ASTM D877/D877M-19 is applicable in several practical contexts within the electrical power industry:

• Routine Quality Testing: Used by manufacturers and utilities to assess whether new or in-use insulating liquids meet minimum dielectric breakdown voltage requirements before use in equipment such as transformers, cables, and switchgear.
• Field Diagnostics: Enables field technicians to quickly evaluate in-service fluids for significant contamination, supporting maintenance decisions and reliability assessments.
• Acceptance and Maintenance: Supports industry guidelines for the acceptance testing of fluids "as delivered" and provides ongoing monitoring for equipment maintenance programs.
• Suitability Determination: Helps identify when further filtration or other treatments are necessary before insulating liquids can be safely placed into high-voltage service.

Note: This method is not recommended for liquids that have been filtered, vacuum-treated, or for those with high viscosity. For those scenarios, refer to ASTM D1816.

Related Standards

Several standards are frequently used in conjunction with or as alternatives to ASTM D877/D877M-19:

• ASTM D1816 – Dielectric Breakdown Voltage of Insulating Liquids Using VDE Electrodes (preferred for processed, filtered, or degassed fluids)
• ASTM D923 – Sampling of Electrical Insulating Liquids
• ASTM D2225 – Test Methods for Silicone Fluids Used for Electrical Insulation
• ASTM D3487/D4652/D6871/D5222 – Specifications for various dielectric fluids
• IEEE C57.106 – Guide for Acceptance and Maintenance of Insulating Oil in Equipment

Summary

ASTM D877/D877M-19 is foundational for ensuring the electrical integrity of insulating liquids in power systems, offering standardized, reproducible procedures for dielectric strength testing. Using this method, technicians and engineers can detect major contamination issues, make informed maintenance decisions, and uphold safety and quality in the deployment of critical electrical infrastructure. For situations demanding higher sensitivity or processed liquids, organizations are advised to consult and apply ASTM D1816 or related standards.

Keywords: dielectric breakdown voltage, insulating liquids, transformer oil testing, ASTM D877, electrical insulating fluids, disk electrodes, power equipment maintenance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D877/D877M − 19
Standard Test Method for
Dielectric Breakdown Voltage of Insulating Liquids Using
Disk Electrodes
This standard is issued under the fixed designation D877/D877M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope used as insulating and cooling liquids in transformers, cables,
and similar apparatus.
1.1 This test method describes two procedures,Aand B, for
1.4.1.2 Procedure A may be used to obtain the dielectric
determining the electrical breakdown voltage of insulating
breakdown of silicone fluid as specified in Test Methods
liquid specimens. The breakdown test uses ac voltage in the
D2225, provided the discharge energy into the sample is less
power-frequency range from 45 to 65 Hz.
than 20 mJ (milli joule) per breakdown for five consecutive
1.2 This test method is used to determine the electrical
breakdowns.
discharge voltage of in-use electrical liquids. It is no longer
1.4.2 Procedure B:
applicabletonewinsulatingliquidsuponreceipt,inwhichcase
1.4.2.1 This procedure is used to determine the breakdown
Test Method D1816 shall be used.
voltage of liquids in which any insoluble breakdown products
NOTE 1—It is understood that long-term histories for this test method
exist, but this test method is no longer considered applicable as numerous do not completely settle from the space between the disks
deficits exist that affect its usefulness. It is recommended to move all new
during the 1-min interval required in Procedure A. Procedure
and in-service electrical discharge voltage testing of electrical insulating
B, modified in accordance with Section 17 of Test Methods
liquids to Test Method D1816.
D2225,isacceptablefortestingsiliconedielectricliquidsifthe
1.3 Limitations of the Procedures:
requirements of 1.4.1.2 can not be achieved.
1.3.1 The sensitivity of this test method to the general
1.4.2.2 Procedure B should also be applied for the determi-
population of contaminants present in a liquid sample de-
nation of the breakdown voltage of liquid samples containing
creasesasappliedtestvoltagesusedinthistestmethodbecome
insolublematerialsthatsettlefromthespecimenduringtesting.
greater than approximately 25 kV rms.
These may include samples taken from circuit breakers, load
1.3.2 If the concentration of water in the sample at room
tap changers, and other liquids heavily contaminated with
temperature is less than 60 % of saturation, the sensitivity of
insoluble particulate material. These examples represent
this test method to the presence of water is decreased. For
samples that may have large differences between replicate
further information refer to RR:D27-1006.
tests. The use of Procedure B will result in a more accurate
1.3.3 The suitability for this test method has not been
value of breakdown voltage when testing such liquids.
determined for a liquid’s viscosity higher than 900 cSt at 40
1.4.2.3 Use Procedure B to establish the breakdown voltage
°C.
of an insulating liquid where an ASTM specification does not
1.4 Procedure Applications
exist or when developing a value for an ASTM guide or
1.4.1 Procedure A:
standard. Procedure A may be used once the single operator
1.4.1.1 Procedure A is used to determine the breakdown
precision of 13.1 has been demonstrated.
voltage of liquids in which any insoluble breakdown products
1.5 The values stated in either SI units or inch-pound units
easily settle during the interval between the required repeated
are to be regarded separately as standard. The values stated in
breakdown tests. These liquids include petroleum oils,
each system are not necessarily exact equivalents; therefore, to
hydrocarbons, natural and synthetic esters, and askarels (PCB)
ensure conformance with the standard, each system shall be
used independently of the other, and values from the two
This test method is under the jurisdiction of ASTM Committee D27 on
systems shall not be combined.
Electrical Insulating Liquids and Gases and is the direct responsibility of Subcom-
1.6 This standard does not purport to address all of the
mittee D27.05 on Electrical Test.
Current edition approved . Published December 2019. Originally approved in
safety concerns, if any, associated with its use. It is the
1946. Last previous edition approved in 2013 as D877/D877M–13. DOI: 10.1520/
responsibility of the user of this standard to establish appro-
D0877_D0877M-19.
priate safety, health, and environmental practices and deter-
RR:D27-1006, Round-Robin Data Using Modified VDE Electrode Cell for
Dielectric Strength Tests on Oil, is available from ASTM Headquarters. mine the applicability of regulatory limitations prior to use.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D877/D877M − 19
1.7 This international standard was developed in accor- 3.5 This test method is used in laboratory or field tests. For
dance with internationally recognized principles on standard- field breakdown results to be comparable to laboratory results,
ization established in the Decision on Principles for the all criteria including room temperature (20 to 30 °C) must be
Development of International Standards, Guides and Recom- met.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Electrical Apparatus
4.1 In addition to this section, use IEEE Standard 4 to
2. Referenced Documents
determine other requirements necessary for conducting test
2.1 ASTM Standards:
methods and making measurements using alternating voltages.
D923 Practices for Sampling Electrical Insulating Liquids
Procedures to ensure accuracy should follow the requirements
D1816 Test Method for Dielectric Breakdown Voltage of
of IEEE Standard 4. Calibration(s) shall be traceable to
Insulating Liquids Using VDE Electrodes
national standards and should be conducted annually or more
D2225 Test Methods for Silicone Fluids Used for Electrical
often.
Insulation
4.1.1 Test Voltage—The test voltage shall be an alternating
D2864 Terminology Relating to Electrical Insulating Liq-
voltage having a frequency in the range from 45 to 65 Hz,
uids and Gases
normally referred to as power-frequency voltage. The voltage
2.2 IEEE Standards:
waveshapeshouldapproximateasinusoidwithbothhalfcycles
Standard 4, IEEE Standard Techniques for High-Voltage
closely alike, and it should have a ratio of peak-to-rms values
Testing
equal to the square root of 2 within 65%.
C57.106 Guide forAcceptance and Maintenance of Insulat-
4.1.2 Generation of the Test Voltage— The test voltage is
ing Oil in Equipment
generally supplied by a transformer or resonant circuit. The
3. Significance and Use voltage in the test circuit should be stable enough to be
practically unaffected by varying current flowing in the capaci-
3.1 The dielectric breakdown voltage is a measure of the
tive and resistive paths of the test circuit. Nondisruptive
ability of an insulating liquid to withstand electrical stress.The
discharges in the test circuit should not reduce the test voltage
power-frequency breakdown voltage of a liquid is reduced by
to such an extent, and for such a time, that the disruptive
thepresenceofcontaminantssuchascellulosicfibers,conduct-
discharge (breakdown) voltage of the test specimen is signifi-
ing particles, dirt, and water. A low result in this test method
cantly affected. In the case of a transformer, the short-circuit
indicates the presence of significant concentrations of one or
current delivered by the transformer should be sufficient to
more of these contaminants in the liquid tested. See Appendix
maintain the test voltage within 3 % during transient current
X1.
pulses or discharges, and a short circuit current of 0.1 A may
3.2 Ahigh breakdown voltage measured in this test method
suffice.
does not necessarily indicate that the amount of the contami-
4.1.3 Disruptive Voltage Measurement— Design the mea-
nants present in a liquid from which the sample was taken is
surement circuit so the voltage recorded at the breakdown is
sufficiently low for the sampled liquid to be acceptable in all
the maximum voltage across the test specimen immediately
electrical equipment. Test Method D877 is not sensitive to low
prior to the disruptive breakdown with an error no greater than
levels of these contaminants. Breakdown in this test method is
3%.
dominated by events occurring at the electrode edges. The
voltage stress distribution between the parallel disk electrodes
4.2 Circuit-Interrupting Equipment— Design the circuit
used in this test method are quasi-uniform and there is
used to interrupt the disruptive discharge through the specimen
substantial stress concentration at the sharp edges of the flat
to operate when the voltage across the specimen has collapsed
disk faces.
to less than 100 V. It is recommended that the circuit design
limit the disruptive current duration and magnitude to low
3.3 This test method may be used for evaluation of insulat-
values that will minimize damage to the disks and limit
ing liquids in equipment that is designed to be filled with
formation of non-soluble materials resulting from the
unprocessed liquids as delivered by a vendor.
breakdown, but consistent with the requirements of 4.1.1.
3.4 This test method is not recommended for evaluation of
4.3 Voltage Control Equipment—Use a rate of voltage rise
the breakdown voltage of liquids used in equipment that
requires the application of vacuum and filtering of the oil of 3 kV/s. The tolerance of the rate of rise should be 5 % for
any new equipment. Automatic equipment should be used to
beforebeingplacedintoservice.TestMethodD1816shouldbe
used to determine the breakdown voltage of filtered and control the voltage rate of rise because of the difficulty of
maintaining a uniform voltage rise manually. The equipment
degassed liquids.
should produce a straight-line voltage-time curve over the
operating range of the equipment. Calibrate and label auto-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
matic controls in terms of rate-of-rise.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
4.4 Measuring Systems—The voltage shall be measured by
the ASTM website.
a method that fulfills the requirements of IEEE Standard No. 4,
Available from The Institute of Electrical and Electronics Engineers, Inc., PO
Box 1331, Piscataway, NJ 08855. giving rms values.
D877/D877M − 19
4.5 Connect the electrodes such that the voltage measured occurs, the cup should be warmed slightly to evaporate any
from each electrode with respect to ground during the test is moisture before use.Take care to avoid touching the electrodes
equal within 5 %. or the inside of the cup after cleaning. Flush the cup using part
of the sample. Fill the cup with a specimen from a sample with
5. Electrodes
aknownbreakdownvoltage.Makeavoltagebreakdowntestas
5.1 The electrodes shall have parallel faces and axes in a specified in this test method. If the breakdown voltage is
judged in the proper range for the sample with a known
coincident horizontal line when mounted in the cup. Construct
the electrodes of polished brass as disks 25.4 mm [1.0 in.] in breakdown value, the test cup is prepared for testing other
samples. If a value lower than expected is obtained, flush or
diameter 62.0 %, and at least 3.18 mm [ ⁄8 in.] thick, and with
sharp edges. The sharp edge shall have a quarter circle radius clean the cup as necessary until test results meet the expected
value for the known sample.
no greater than 0.254 mm [0.010 in.]. Refer to Annex A1 for
illustrations of measuring edge radius.
7.4 Electrode Edge Verification—Using a 0.254-mm [0.010-
in.] equivalent radius gauge or an optical comparator, verify
6. Test Cup
that the radius of the edge of the electrode, on the gap side, is
6.1 Construct the cup of a material having high dielectric
lessthan0.254mm[0.010in.];verifythefaceoftheelectrodes
strength, that is inert to any of the cleaning or test liquids. The
are at 90 6 1° to the side edge of the electrode. If the edge
cup material shall not absorb moisture or the cleaning and test
radius is no greater than the value specified and the sides are at
liquids. The vector sum of the resistive and capacitive current
90°, the electrodes are satisfactory for continued use. Check
of the cup, when filled with insulating liquid, shall be less than
the disk in at least four locations for each criteria. If the radius
200 µAat 20 kV, at power frequency. Construct the cup so that
exceeds the tolerance or the edges are not at 90°, the electrodes
no part is less than 12.7 mm [0.5 in.] from any part (the side,
shall be resurfaced to the specified values. Refer to Annex A1
back or edge) of the electrode disk. The cup shall be designed
for illustrations of measuring edge radius.
to permit easy removal of the electrodes for cleaning and
7.5 Polishing of Electrodes—When examination of elec-
polishing, verification that the sharp edge is within the speci-
trodes shows minor scratching or pitting, the electrodes should
fied tolerance, and to permit easy adjustment of the gap
be removed from the test cup and polished by buffing with
spacing. The top of the cup shall be maintained at least 25.4
jeweler’s rouge using a soft cloth or soft buffing wheel.
mm [1.0 in.] above the top of the electrodes.
(Resurfacing may be necessary in order to remove deep pit
marks or edge damage.) Care must be taken in resurfacing or
7. Adjustment and Care of Electrodes and Test Cup
in polishing to ensure that the electrode faces remain p
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D877/D877M − 13 D877/D877M − 19
Standard Test Method for
Dielectric Breakdown Voltage of Insulating Liquids Using
Disk Electrodes
This standard is issued under the fixed designation D877/D877M; 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 (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method describes two procedures, A and B, for determining the electrical breakdown voltage of insulating liquid
specimens. The breakdown test uses ac voltage in the power-frequency range from 45 to 65 Hz.
1.2 This test method is used to judge if the disk electrode breakdown voltage requirements are met for insulating liquids, as
delivered from the manufacturer, that have never been filtered or dried. See Specification determine the electrical discharge voltage
of in-use electrical liquids. It is no longer applicable to new insulating liquids upon receipt, in which case Test Method
D3487D1816, Specification shall D4652, Specification D6871 and Guide D5222 for the minimum specified electrical breakdown.
This test method should be used as recommended by professional organization standards such as IEEE C57.106.be used.
NOTE 1—It is understood that long-term histories for this test method exist, but this test method is no longer considered applicable as numerous deficits
exist that affect its usefulness. It is recommended to move all new and in-service electrical discharge voltage testing of electrical insulating liquids to Test
Method D1816.
1.3 Limitations of the Procedures:
1.3.1 The sensitivity of this test method to the general population of contaminants present in a liquid sample decreases as
applied test voltages used in this test method become greater than approximately 25 kV rms.
1.3.2 If the concentration of water in the sample at room temperature is less than 60 % of saturation, the sensitivity of this test
method to the presence of water is decreased. For further information refer to RR:D27-1006.
1.3.3 The suitability for this test method has not been determined for a liquid’s viscosity higher than 900 cSt at 40°C.40 °C.
1.4 Procedure Applications
1.4.1 Procedure A:
1.4.1.1 Procedure A is used to determine the breakdown voltage of liquids in which any insoluble breakdown products easily
settle during the interval between the required repeated breakdown tests. These liquids include petroleum oils, hydrocarbons,
natural and synthetic esters, and askarels (PCB) used as insulating and cooling liquids in transformers, cables, and similar
apparatus.
1.4.1.2 Procedure A may be used to obtain the dielectric breakdown of silicone fluid as specified in Test Methods D2225,
provided the discharge energy into the sample is less than 20 mJ (milli joule) per breakdown for five consecutive breakdowns.
1.4.2 Procedure B:
1.4.2.1 This procedure is used to determine the breakdown voltage of liquids in which any insoluble breakdown products do
not completely settle from the space between the disks during the 1–min1-min interval required in Procedure A. Procedure B,
modified in accordance with Section 17 of Test Methods D2225, is acceptable for testing silicone dielectric liquids if the
requirements of 1.4.1.2 can not be achieved.
1.4.2.2 Procedure B should also be applied for the determination of the breakdown voltage of liquid samples containing
insoluble materials that settle from the specimen during testing. These may include samples taken from circuit breakers, load tap
changers, and other liquids heavily contaminated with insoluble particulate material. These examples represent samples that may
have large differences between replicate tests. The use of Procedure B will result in a more accurate value of breakdown voltage
when testing such liquids.
This test method is under the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Subcommittee D27.05
on Electrical Test.
Current edition approved Dec. 1, 2013. Published January 2014December 2019. Originally approved in 1946. Last previous edition approved in 20072013 as
D877–02(2007).D877/D877M–13. DOI: 10.1520/D0877_D0877M-13.10.1520/D0877_D0877M-19.
RR:D27-1006, Round-Robin Data Using Modified VDE Electrode Cell for Dielectric Strength Tests on Oil, is available from ASTM Headquarters.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D877/D877M − 19
1.4.2.3 Use Procedure B to establish the breakdown voltage of an insulating liquid where an ASTM specification does not exist
or when developing a value for an ASTM guide or standard. Procedure A may be used once the single operator precision of 13.1
has been demonstrated.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other, and values from the two systems shall not be combined.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D923 Practices for Sampling Electrical Insulating Liquids
D1816 Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using VDE Electrodes
D2225 Test Methods for Silicone Fluids Used for Electrical Insulation
D2864 Terminology Relating to Electrical Insulating Liquids and Gases
D3487 Specification for Mineral Insulating Oil Used in Electrical Apparatus
D4652 Specification for Silicone Fluid Used for Electrical Insulation
D5222 Specification for High Fire-Point Mineral Electrical Insulating Oils
D6871 Specification for Natural (Vegetable Oil) Ester Fluids Used in Electrical Apparatus
2.2 IEEE Standards:
Standard 4, IEEE Standard Techniques for High-Voltage Testing
C57.106 Guide for Acceptance and Maintenance of Insulating Oil in Equipment
3. Significance and Use
3.1 The dielectric breakdown voltage is a measure of the ability of an insulating liquid to withstand electrical stress. The
power-frequency breakdown voltage of a liquid is reduced by the presence of contaminants such as cellulosic fibers, conducting
particles, dirt, and water. A low result in this test method indicates the presence of significant concentrations of one or more of these
contaminants in the liquid tested. See Appendix X1.
3.2 A high breakdown voltage measured in this test method does not necessarily indicate that the amount of the contaminants
present in a liquid from which the sample was taken is sufficiently low for the sampled liquid to be acceptable in all electrical
equipment. Test Method D877 is not sensitive to low levels of these contaminants. Breakdown in this test method is dominated
by events occurring at the electrode edges. The voltage stress distribution between the parallel disk electrodes used in this test
method are quasi-uniform and there is substantial stress concentration at the sharp edges of the flat disk faces.
3.3 This test method may be used for evaluation of insulating liquids in equipment that is designed to be filled with unprocessed
liquids as delivered by a vendor.
3.4 This test method is not recommended for evaluation of the breakdown voltage of liquids used in equipment that requires
the application of vacuum and filtering of the oil before being placed into service. Test Method D1816 should be used to determine
the breakdown voltage of filtered and degassed liquids.
3.5 This test method is used in laboratory or field tests. For field breakdown results to be comparable to laboratory results, all
criteria including room temperature (20 to 30°C) 30 °C) must be met.
4. Electrical Apparatus
4.1 In addition to this section, use IEEE Standard 4 to determine other requirements necessary for conducting test methods and
making measurements using alternating voltages. Procedures to ensure accuracy should follow the requirements of IEEE Standard
4. Calibration(s) shall be traceable to national standards and should be conducted annually or more often.
4.1.1 Test Voltage—The test voltage shall be an alternating voltage having a frequency in the range from 45 to 65 Hz, normally
referred to as power-frequency voltage. The voltage waveshape should approximate a sinusoid with both half cycles closely alike,
and it should have a ratio of peak-to-rms values equal to the square root of 2 within 65 %.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from The Institute of Electrical and Electronics Engineers, Inc., PO Box 1331, Piscataway, NJ 08855.
D877/D877M − 19
4.1.2 Generation of the Test Voltage— The test voltage is generally supplied by a transformer or resonant circuit. The voltage
in the test circuit should be stable enough to be practically unaffected by varying current flowing in the capacitive and resistive
paths of the test circuit. Nondisruptive discharges in the test circuit should not reduce the test voltage to such an extent, and for
such a time, that the disruptive discharge (breakdown) voltage of the test specimen is significantly affected. In the case of a
transformer, the short-circuit current delivered by the transformer should be sufficient to maintain the test voltage within 3 %
during transient current pulses or discharges, and a short circuit current of 0.1 A may suffice.
4.1.3 Disruptive Voltage Measurement— Design the measurement circuit so the voltage recorded at the breakdown is the
maximum voltage across the test specimen immediately prior to the disruptive breakdown with an error no greater than 3 %.
4.2 Circuit-Interrupting Equipment— Design the circuit used to interrupt the disruptive discharge through the specimen to
operate when the voltage across the specimen has collapsed to less than 100 V. It is recommended that the circuit design limit the
disruptive current duration and magnitude to low values that will minimize damage to the disks and limit formation of non-soluble
materials resulting from the breakdown, but consistent with the requirements of 4.1.1.
4.3 Voltage Control Equipment—Use a rate of voltage rise of 3 kV/s. The tolerance of the rate of rise should be 5 % for any
new equipment. Automatic equipment should be used to control the voltage rate of rise because of the difficulty of maintaining
a uniform voltage rise manually. The equipment should produce a straight-line voltage-time curve over the operating range of the
equipment. Calibrate and label automatic controls in terms of rate-of-rise.
4.4 Measuring Systems—The voltage shall be measured by a method that fulfills the requirements of IEEE Standard No. 4,
giving rms values.
4.5 Connect the electrodes such that the voltage measured from each electrode with respect to ground during the test is equal
within 5 %.
5. Electrodes
5.1 The electrodes shall have parallel faces and axes in a coincident horizontal line when mounted in the cup. Construct the
electrodes of polished brass as disks 25.4 mm [1.0 in.] in diameter 62.0 %, and at least 3.18 mm [ ⁄8 in.] thick, and with sharp
edges. The sharp edge shall have a quarter circle radius no greater than 0.254 mm [0.010 in.]. Refer to Annex A1 for illustrations
of measuring edge radius.
6. Test Cup
6.1 Construct the cup of a material having high dielectric strength, that is inert to any of the cleaning or test liquids. The cup
material shall not absorb moisture or the cleaning and test liquids. The vector sum of the resistive and capacitive current of the
cup, when filled with oil meeting the requirements of Specification insulating liquid, D3487, shall be less than 200 μA at 20 kV,
at power frequency. Construct the cup so that no part is less than 12.7 mm [0.5 in.] from any part (the side, back or edge) of the
electrode disk. The cup shall be designed to permit easy removal of the electrodes for cleaning and polishing, verification that the
sharp edge is within the specified tolerance, and to permit easy adjustment of the gap spacing. The top of the cup shall be
maintained at least 25.4 mm [1.0 in.] above the top of the electrodes.
7. Adjustment and Care of Electrodes and Test Cup
7.1 Daily Use—At the beginning of each day’s testing examine the electrodes for scratches, pitting, and contamination. If pitting
or scratches of the disk faces are found, polish in accordance with 7.5. For severe problems resurfacing may be required. The
electrodes should be examined quarterly in accordance with 7.4 for the proper sharp edge, if there is apparent edge damage, or
upon return from resurfacing. The gap shall be reset in accordance with 7.2. Clean and prepare the cup in accordance with 7.3.
7.2 Electrode Spacing—Gauges shall be used to set the spacing of the electrodes during tests to 2.54 mm [0.100 in.] + 0.0254
mm [0.001 in.]. The gap should be set with “go” and “no-go” gauges such that the spacing is no less than 2.51 mm [0.0990 in.]
for a “go” measurement and no larger than 2.57 mm [0.1010 in.]. If the “no-go” gauge can enter the gap, the gap must be reset.
Alternatively, if the cup is supplied with a vernier scale for setting the gap, it can be used following the manufacturer’s instructions.
Vernier scales are to be verified at least monthly with gauges. Recheck the spacing following any disturbance of the cup or
electrodes and at operation in the beginning of each day’s testing.
7.3 Cleaning—Wipe the electrodes and the cup clean with dry, lint-free tissue paper or a clean dry chamois. It is important to
avoid touching the electrodes o
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