ASTM E2047-10(2019)
(Test Method)Standard Test Method for Wet Insulation Integrity Testing of Photovoltaic Arrays
Standard Test Method for Wet Insulation Integrity Testing of Photovoltaic Arrays
SIGNIFICANCE AND USE
5.1 The design of a PV module or system intended to provide safe conversion of the sun's radiant energy into useful electricity must take into consideration the possibility of hazard should the user come into contact with the electrical potential of the array. In addition, the insulation system provides a barrier to electrochemical corrosion, and insulation flaws can result in increased corrosion and reliability problems. This test method describes a procedure for verifying that the design and construction of the array provides adequate electrical isolation through normal installation and use. At no location on the array should the PV-generated electrical potential be accessible, with the obvious exception of the output leads. The isolation is necessary to provide for safe and reliable installation, use, and service of the PV system.
5.2 This test method describes a procedure for determining the ability of the array to provide protection from electrical hazards. Its primary use is to find insulation flaws that could be dangerous to persons who may come into contact with the array. Corrective action taken to address such flaws is beyond the scope of this test method.
5.3 This procedure may be specified as part of a series of acceptance tests involving performance measurements and demonstration of functional requirements. Large arrays can be tested in smaller segments. The size of the array segment to be tested (called “circuit under test” in this test method) is usually selected at a convenient break point and sized such that the expected resistance or current reading is within the middle third of the meter's range.
5.4 Insulation leakage resistance and insulation leakage current leakage are strong functions of array dimensions, ambient relative humidity, absorbed water vapor, and other factors. For this reason, it is the responsibility of the user of this test method to specify the minimum acceptable leakage resistance for this test.
5.4.1 Even though a...
SCOPE
1.1 This test method covers a procedure to determine the insulation resistance of a photovoltaic (PV) array (or its component strings), that is, the electrical resistance between the array's internal electrical components and is exposed, electrically conductive, non-current carrying parts and surfaces of the array.
1.2 This test method does not establish pass or fail levels. The determination of acceptable or unacceptable results is beyond the scope of this test method.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 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.
General Information
Relations
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: E2047 − 10 (Reapproved 2019) An American National Standard
Standard Test Method for
Wet Insulation Integrity Testing of Photovoltaic Arrays
This standard is issued under the fixed designation E2047; 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.
1. Scope 3. Terminology
1.1 This test method covers a procedure to determine the 3.1 Definitions—Definitions of terms used in this test
insulation resistance of a photovoltaic (PV) array (or its method may be found in Terminologies E772 and E1328.
component strings), that is, the electrical resistance between
3.2 Definitions of Terms Specific to This Standard:
the array’s internal electrical components and is exposed,
3.2.1 insulation resistance, n—the electrical resistance of a
electrically conductive, non-current carrying parts and surfaces
photovoltaic array’s insulation, measured between the photo-
of the array.
voltaic circuit and exposed, electrically conductive non-
1.2 This test method does not establish pass or fail levels. current-carrying parts and surfaces of the array.
The determination of acceptable or unacceptable results is
3.2.2 metal oxide varistor MOV, n—a surge protection
beyond the scope of this test method.
device.
1.3 The values stated in SI units are to be regarded as
3.2.3 photovoltaic circuit—the active electrical circuit that
standard. No other units of measurement are included in this
conducts the photovoltaic generated power.
standard.
4. Summary of Test Method
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 A procedure is provided for testing the electrical isola-
responsibility of the user of this standard to establish appro-
tion between the array’s internal electrical components and its
priate safety, health, and environmental practices and deter-
exposed, electrically conductive, non-current carrying parts
mine the applicability of regulatory limitations prior to use.
and surfaces of the array.
1.5 This international standard was developed in accor-
4.2 The procedure offers two ways to connect the array
dance with internationally recognized principles on standard-
during the test, either open-circuited or short-circuited. Each
ization established in the Decision on Principles for the
option has advantages and disadvantages (see 5.5).
Development of International Standards, Guides and Recom-
4.3 Awetting solution is applied to the array, then a voltage
mendations issued by the World Trade Organization Technical
is applied between the PV circuit and the exposed, electrically
Barriers to Trade (TBT) Committee.
conductive, non-current carrying parts and surfaces of the
2. Referenced Documents
array, while monitoring the current or resistance, to find
localized regions where the insulation resistance is signifi-
2.1 ASTM Standards:
cantly reduced by the wetting solution. The array is then
E772 Terminology of Solar Energy Conversion
inspected for evidence of possible arcing.
E1328 Terminology Relating to Photovoltaic Solar Energy
Conversion (Withdrawn 2012)
5. Significance and Use
E1462 Test Methods for Insulation Integrity and Ground
Path Continuity of Photovoltaic Modules 5.1 The design of a PV module or system intended to
provide safe conversion of the sun’s radiant energy into useful
electricitymusttakeintoconsiderationthepossibilityofhazard
This test method is under the jurisdiction of ASTM Committee E44 on Solar,
should the user come into contact with the electrical potential
GeothermalandOtherAlternativeEnergySources,andisthedirectresponsibilityof
Subcommittee E44.09 on Photovoltaic Electric Power Conversion.
of the array. In addition, the insulation system provides a
Current edition approved April 1, 2019. Published April 2019. Originally
barrier to electrochemical corrosion, and insulation flaws can
approvedin1999.Lastpreviouseditionapprovedin2015asE2047–10(2015).DOI:
result in increased corrosion and reliability problems. This test
10.1520/E2047-10R19.
method describes a procedure for verifying that the design and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
construction of the array provides adequate electrical isolation
Standards volume information, refer to the standard’s Document Summary page on
through normal installation and use.At no location on the array
the ASTM website.
should the PV-generated electrical potential be accessible, with
The last approved version of this historical standard is referenced on
www.astm.org. the obvious exception of the output leads. The isolation is
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2047 − 10 (2019)
necessary to provide for safe and reliable installation, use, and 6.2 Wetting Solution—Asolution of tap water and a wetting
service of the PV system. agent , with a surface tension of 0.03 N/m or less at 23°C.
6.3 Spray Apparatus—A system for applying the wetting
5.2 This test method describes a procedure for determining
solution to the array, capable of providing a water pressure of
the ability of the array to provide protection from electrical
35 kPa. The force and flow rate of the wetting solution must
hazards. Its primary use is to find insulation flaws that could be
be sufficient to reach all of the test segment surfaces and
dangerous to persons who may come into contact with the
maintain wetted surfaces, front and back.
array. Corrective action taken to address such flaws is beyond
the scope of this test method.
NOTE 1—The spray pressure is only enough to completely wet the
exposed surfaces; it is not intended to penetrate enclosed spaces such as
5.3 This procedure may be specified as part of a series of
the interiors of junction boxes. It is not necessary to use a forceful stream
because the wetting agent helps to penetrate small crevices.
acceptance tests involving performance measurements and
demonstration of functional requirements. Large arrays can be
6.4 Array Shorter—A dc-rated switch, circuit beaker or
tested in smaller segments. The size of the array segment to be
other device capable of interrupting the maximum short circuit
tested (called “circuit under test” in this test method) is usually current of the circuit under test. The array shorter is only
selected at a convenient break point and sized such that the required if the short-circuited option is used.
expected resistance or current reading is within the middle 6.4.1 The array shorter must be rated for the maximum
third of the meter’s range. open-circuit voltage of the circuit under test plus the insulation
tester or ohmmeter.
5.4 Insulation leakage resistance and insulation leakage
6.4.2 The wiring between the array shorter and the positive
current leakage are strong functions of array dimensions,
and negative terminals of the circuit under test must also be
ambient relative humidity, absorbed water vapor, and other
rated for the continuous maximum short-circuit current of the
factors.Forthisreason,itistheresponsibilityoftheuserofthis
circuit under test.
test method to specify the minimum acceptable leakage resis-
7. Hazards
tance for this test.
5.4.1 Even though a numerical quantity is specified, actual
7.1 Touchingthemodulesorarrayduringthetestingmaybe
results are often pass-fail in that when a flaw is found, the
hazardous because of the high voltage applied.
leakage current changes from almost nothing to the full scale
7.2 Use caution whenever short circuiting any high voltage
value on the meter.
PV array. It may be advisable to reduce the risk involved by
short-circuiting the array at night, when the current and voltage
5.5 The user of this test method must specify the option
are minimized.
used for connection to the array during the test. The short-
circuited option requires a shorting device with leads to 7.3 The megohmmeter or insulation tester should be turned
connect the positive and negative legs of the circuit under test. off while wetting the array. This may not always be desirable,
For larger systems, where the shorting device may have to be such as when trying to pinpoint the location of an insulation
flaw.Inthesecases,appropriatepersonnelprotection(electrical
rated for high current and voltage levels, the open-circuited
gloves with keepers, safety glasses, etc.) should be worn and
option may be preferred. The open-circuited option requires
care should be taken to keep the wetting solution from entering
the user to correct readings to account for the PV-generated
the gloves, boots, etc.
voltage, and the procedure for making such corrections is
beyond the scope of this test method. The short-circuited
8. Procedure
option may be easier for small systems where the voltage and
8.1 Assemble the requisite equipment and personnel at the
current levels are low and the distance between the plus and
array to be tested.
minus leads of the circuit under test are small. The short-
circuited option minimizes the chance of exposing array
8.2 Prepare the wetting solution.
components to voltage levels above those for which they are
8.3 Measure and record the site meteorological conditions
rated.
(irradiance, ambient temperature, wind speed) or arrange for
the data to be measured by the site data acquisition system.
6. Apparatus
NOTE 2—It is recommended that this test not be performed under
6.1 Choose one of the following, depending on the option conditionswheretheambienttemperatureisgreaterthan40°Corthewind
speed is greater than 7.5 m/s, since high values of either make it difficult
selected (see 4.2 and 5.5):
to keep the
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