INTERSTATE STANDARD

ELECTRIC INSULATING VARNISH ML-92

Specifications

Official edition

IPK PUBLISHING STANDARDS Moscow

INTERSTATE STANDARD

ELECTRIC INSULATING VARNISH ML-92

Specifications

Insulating varnish ML-92. Specifications

MKS 29.040.99 87.040

OKP 23 1131 1100 07

Introduction date 01.01.71

This standard applies to electrical insulating varnish ML-92, which is a solution of a mixture of glyptal varnish and melamine-formaldehyde resin K-421-02 in organic solvents.

Lacquer ML-92 is intended for impregnation of windings of electrical machines, devices and transformers and for coating electrical insulating parts. Lacquer ML-92 has a heat resistance class B according to GOST 8865.

Mandatory requirements aimed at ensuring the safety of the ML-92 varnish for the life, health and property of citizens, environmental protection are set out in paragraphs. 1.1 (Table 1, indicators 4, 12, 13), 3.1, 3.2.

(Changed edition, Rev. No. 4, 5).

1. TECHNICAL REQUIREMENTS

1.1. According to the physicochemical and electrical parameters, the ML-92 varnish must comply with the requirements and standards specified in Table. 1.

Table 1

Name of indicator		Test method
1. The presence of mechanical inclusions in the varnish	Absence	According to GOST 13526
2. Appearance coatings	After the varnish has dried
3. Relative viscosity according to a VZ-246 type viscometer with a nozzle diameter of 4 mm at a temperature of (20.0 + 0.5) ° C, s 4. Mass fraction of non-volatile substances in varnish,%	should form a glossy smooth, uniform surface in color from light brown to dark brown	According to GOST 8420 According to GOST 17537 and clause 2.7 of this standard
5. Acid number, mg KOH, no more		According to GOST 13526
6. (Deleted, Rev. No. 4). 7. Drying time to degree 3 at a temperature of 105-110 ° C, h, no more		According to GOST 19007 and clause 2.10 of this standard
8. The ability to dry the varnish in a thick layer at a temperature of 115-120 ° C, h, no more		According to GOST 13526 and clause 2.11 of this standard
Official edition		Reprint prohibited

© IPK Standards Publishing House, 2003

Continuation of the table. 1

Name of indicator		Test method
9. Thermoelasticity of the film at temperature		According to GOST 13526 and clause 2.12 of this
(150 + 2) °С, h, not less than		common standard
10. The hardness of the coating according to the pendulum		According to GOST 5233 and clause 2.13.2.2, this
boron at a temperature of (20 + 2) °C, not less than:		common standard
type TML (pendulum A), relative units
or type M-3, conventional units
11. Film oil resistance, N, not less than		According to GOST 13526 and clause 2.14, insist
12. Dielectric strength of the film, MV/m, not		common standard According to GOST 6433.3, GOST 13526,
		GOST 6433.1, GOST 10315 and according to clause 2.15
at a temperature of (20 + 2) °С		this standard
at a temperature of (130 + 2) °С
13. Specific volumetric electrical resistance		According to GOST 6433.2, GOST 13526,
Film tension, Ohm m, not less than:		GOST 6433.1, GOST 10315 and clause 2.15
at a temperature of (20 + 2) °С		this standard
at a temperature of (130 + 2) °С
after the action of water for 24 hours at a temperature of (20 + 2) ° C

1.2. Lacquer ML-92 must be produced in accordance with the requirements of this standard according to the recipe and technological regulations approved in the prescribed manner.

(Revised edition, Rev. No. 2).

1.3. (Deleted, Rev. No. 2).

1.4. If necessary, before use, the varnish is diluted to working viscosity with toluene (GOST 14710 or GOST 9880), xylene (GOST 9949 or GOST 9410) or a mixture of one of these solvents with white spirit (nefras-C4-155/200) (GOST 3134) in ratio of at least 3:1.

1.5. 1.6. (Deleted, Rev. No. 2).

1a. Safety requirements

la. 1. Lacquer ML-92 is a fire hazardous and toxic material, which is due to the properties of the components that make up its composition.

Maximum permissible concentrations, hazard classes of components according to GOST 12.1.005 and fire hazard characteristics according to GOST 12.1.044 are given in Table. 2.

table 2

* Lower flammable limit at 25°C and 101325 Pa (760 mm Hg).

1a.2. Possible routes of entry of harmful substances into the human body are inhalation and through the skin.

Solvent vapors at high concentrations in the air irritate the mucous membranes of the eyes, upper respiratory tract and skin.

1a.3. The production of varnish must comply with the safety rules of paint and varnish production, approved in the prescribed manner.

1a.4. Production, testing and application of varnish must comply with GOST 12.3.005 and GOST 12.1.004.

1a. 5. Persons involved in the manufacture and use of varnish must be provided with special clothing in accordance with GOST 12.4.103 and personal protective equipment in accordance with GOST 12.4.011, GOST 12.4.068.

Individual means of respiratory protection against solvent vapors - according to GOST 12.4.028, GOST 12.4.004 and GOST 17269.

1a.6. Works related to the manufacture and use of varnish are carried out in rooms equipped with supply and exhaust and local ventilation in accordance with GOST 12.4.021, which ensures the state of the air environment in accordance with GOST 12.1.005.

Fire extinguishers - sand, felt, foam fire extinguishers OHP-10, carbon dioxide OU-2 and OU-5, water mist, foam installations - according to GOST 12.4.009.

1a.7. To protect atmospheric air from pollution, air purification at gas treatment plants and control over compliance with maximum allowable emissions (MAE) in accordance with GOST 17.2.3.02 should be provided.

1a.8. Waste generated during the cleaning of equipment is disposed of in accordance with the procedure for the accumulation, transportation, neutralization and disposal of toxic industrial waste.

Sec. 1a.

16. ACCEPTANCE RULES

16.1. Acceptance rules - according to GOST 9980.1.

(Changed edition, Rev. No. 2, 4).

16.2. Acceptance tests are carried out according to indicators 1-7, 10, 12, 13 of the table. 1.

Upon receipt of unsatisfactory results of acceptance tests for at least one of the indicators, repeated tests are carried out on a double sample taken from the same batch.

The test results apply to the entire batch.

Norms for indicators 8, 9 table. 1 is determined periodically in every tenth batch.

The rate for indicator 11 is determined at least once a year from the calendar date of the beginning of the release of varnish.

Upon receipt of unsatisfactory results of periodic tests, each lot is checked until satisfactory results are obtained in a row at least on three lots.

Upon receipt of a repeated negative result, periodic tests are transferred to acceptance tests until satisfactory results are obtained.

(Revised edition, Rev. No. 5).

16.3. (Deleted, Rev. No. 5).

2. TEST METHODS

2.1, 2.2. (Deleted, Rev. No. 2).

2.3. Sampling - according to GOST 9980.2.

2.3a. Indicators - the appearance of the coating, the relative viscosity according to the VZ-246 (or VZ-4) viscometer, the mass fraction of non-volatile substances, the acid number, the ability to dry out in a thick layer - are determined in undiluted varnish.

(Changed edition, Rev. No. 3, 4, 5).

2.4. (Deleted, Rev. No. 3).

2.5. The appearance of the varnish coating is determined visually in natural diffused light. The varnish is applied in bulk in one layer with an initial viscosity of 25-50 s on a clean glass plate 90 x 120 mm in size, 1.2 to 1.8 mm thick. The plate is placed at an angle of 45 ° in a protected from

dust place and kept at a temperature of (20 ± 2) ° C for 15-20 minutes, then dried at a temperature of 105-110 ° C for 1 hour. After cooling, consider the varnish coating.

(Revised edition, Rev. No. 5).

2.6. (Deleted, Rev. No. 4).

2.7. To determine the mass fraction of non-volatile substances in varnish, a sample of varnish weighing 1.5-2 g is placed in an oven and kept at a temperature of (120 ± 2) ° C for 1 hour.

(Revised edition, Rev. No. 3).

2.8. (Deleted, Rev. No. 3).

2.9-2.9.2. (Deleted, Rev. No. 4).

2.10. The drying time of the varnish film is determined in accordance with GOST 19007 on plates of soft copper tape 0.1 mm thick according to regulatory documentation. The varnish is applied in accordance with GOST 13526. The first layer of varnish before repeated dipping and the second layer of varnish before hot drying is kept at (20 ± 2) ° C for 15-20 minutes. Then the lacquered plates are dried at 105-110°C for 1 hour.

(Revised edition, Rev. No. 5).

2.11. The ability to dry the varnish in a thick layer is determined according to GOST 13526 at a temperature of 115-120 ° C for 16 hours. Before hot drying, the boxes with varnish are kept at (20 ± 2) ° C for 30 minutes. The condition of the sample after heat treatment shall comply with SI U-2-I (3-4)2. The drying of the lower surface of the sample after its curing is checked as follows: a sheet of filter paper (GOST 12026) is placed on each sample, turned upside down. square shape with a side of 24-25 mm, on top of which a rubber disk with a diameter of 22 mm and a thickness of 5 mm is placed, and then a cylindrical load weighing 500 g. After 1 min, the sample is checked for compliance with the requirements of Table. 3 GOST 13526.

(Changed edition, Rev. No. 3, 4, 5).

2.12. The thermoelasticity of the lacquer film is determined according to GOST 13526 on plates of soft copper tape 0.1 mm thick according to regulatory documentation. The varnish is applied and dried according to clause 2.10, while the second layer of varnish is dried at 115-120 ° C for 1 hour. Then the plates are kept in a thermostat at a temperature of (150 ± 2) ° C for 48 hours. The samples are removed from the thermostat, cooled to (20 ± 2) °C and tested in accordance with GOST 6806 around a rod with a diameter of 3 mm.

(Changed edition, Rev. No. 3, 5).

2.13. Determination of coating hardness

(Revised edition, Rev. No. 5).

2.13.1. The hardness of the varnish coating is determined according to GOST 5233, Sec. 1.

2.13.2. Determination of coating hardness by pendulum device type M-3.

2.13.2.1. Equipment and materials

Pendulum device type M-3 for determining hardness at room temperature (20 ± 2) ° C (drawing).

The main characteristics of the pendulum device:

Pendulum mass (120 ± 1) g;

The length of the pendulum, counting from the fulcrum to the end of the arrow, (500 ± 1) mm;

Steel ball diameter (support point) 7.938 mm according to GOST 3722;

Instrument scale divided into degrees;

Angle of deviation from 5 to 2°;

Decay time of oscillations on a glass plate (“glass number”) (440 ± 6) s.

Glass plates measuring 90 x 120 mm, thickness from 1.2 to 1.8 mm.

Stopwatch.

Solvents: ethyl ether according to GOST 8981 or technical acetone according to GOST 2768.

1 - trigger mechanism; 2 - base; 3 - scale; 4 - set screws; 5-cargo; 6-two-hand mechanism; 7-tripod; 8- connecting bar; 9- frame; 10- table;

11 - steel balls; 12- plumb

2.13.2.2. Preparing for the test

Before each test, the pendulum support balls and the glass plate of the instrument are carefully wiped with cotton wool moistened with a solvent, and then with dry, clean gauze.

On the plates prepared in accordance with GOST 8832, the tested varnish is applied in accordance with GOST 13526, kept at a temperature of (20 ± 2) ° C for 15-20 minutes and dried at a temperature of 115-120 ° C for 6 hours.

2.13.2.3. Conducting a test

The pendulum device is checked by the "glass number" - the decay time of the pendulum oscillations, the fulcrum of which lies on the glass plate of the device.

The determination of the "glass number" is carried out at a temperature of (20 ± 2) °C and relative air humidity (65 ± 5)%.

Measurements are carried out on at least three areas of the surface of the glass plate. In the same way, the decay time of the pendulum oscillations on a glass plate with a lacquer coating is determined.

2.13.2.4. Results processing

Hardness (H), conventional units, is calculated by the formula

where t is the decay time of the pendulum oscillations on the tested lacquer coating, s;

C is the decay time of the pendulum oscillations on the glass plate of the instrument (“glass number”), s.

The test result is taken as the arithmetic mean of the results of measuring the decay time of the pendulum oscillations on the glass plate of the device and on the tested sample of the varnish coating.

Deviations of the values ​​of individual measurements from the arithmetic mean should not be more than 3%.

In case of disagreement, the “coating hardness” indicator is determined according to GOST 5233 using a TML-type pendulum device (pendulum A).

2.13.2.5. Method error

The error of the method in determining the hardness on the device M-3 is ± 0.02 conventional units.

2.13.1-2.13.2.5. (Introduced additionally, Amendment No. 5).

2.14. The oil resistance of the lacquer film is determined according to GOST 13526 on plates of soft copper tape 0.1 mm thick according to regulatory documentation. Applying varnish and intermediate drying is carried out according to clause 2.10. Then the lacquered plates are dried at 115–120°C for 6 hours.

(Revised edition, Rev. No. 5).

2.15. Electrical strength and specific volumetric electrical resistance are determined on plates of cold-rolled copper sheet (GOST 495) 100 x 100 mm in size, 0.4-0.6 mm thick. The varnish is applied and dried according to clause 2.14.

Determination of electrical strength is carried out on two plates of volumetric electrical resistance on at least three samples.

The electrical strength is determined using copper electrodes, the diameter of the upper electrode should be 25 mm. Use of electrodes from stainless steel is allowed.

When determining the specific volumetric electrical resistance, measuring and guard electrodes are used in the form of aluminum foil ground to the surface of the sample.

The dielectric strength is measured with a gradual rise in voltage at such a rate that breakdown occurs in the range from 10 to 20 s after the start of the voltage rise. When determining the specific volumetric electrical resistance, samples that have not been exposed to media and elevated temperatures are tested at voltages of 100–500 V. After exposure to various media and at elevated temperatures, tests are carried out at voltages of 100–250 V.

Conditions for normalization, conditioning and testing of electrical strength and volume electrical resistivity:

1 hour (20 °C) 65%; M (15-35 ° C) 45-75%;

1 hour (20 °C) 65%; M (130 °С)< 20 %;

1 hour (20°C) 65% + 24 hours [(23.0 ± 0.5)°C] distilled water;

M (15-35 ° C) 45-75%.

(Changed edition, Rev. No. 3, 4).

3. PACKAGING, LABELING, TRANSPORT AND STORAGE

3.1. Packaging - according to GOST 9980.3.

(Revised edition, Rev. No. 4).

3.2. Marking - according to GOST 9980.4.

The transport container must be marked with a danger sign in accordance with GOST 19433 (class 3), classification code 3313, UN number 1263.

3.3. Transportation and storage of varnish - according to GOST 9980.5.

During storage, the relative viscosity of the varnish increases from the norm according to the table. 1. When diluting the varnish with a solvent to the norm in terms of "viscosity", the varnish must comply with the requirements of this standard.

3.2, 3.3. (Changed edition, Rev. No. 4, 5).

4.1. The manufacturer guarantees the conformity of the varnish with the requirements of this standard, subject to the storage and transportation conditions.

4.2. Warranty period of storage of varnish - 12 months from the date of manufacture.

4.1, 4.2. (Revised edition, Rev. No. 3).

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Chemical Industry

2. APPROVED AND PUT INTO EFFECT by the Decree of the Committee of Standards, Measures and Measuring Instruments under the Council of Ministers of the USSR dated April 15, 1970 No. 513

Amendment No. 5 adopted by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 20 dated 01.11.2001)

Registered by the IGU Standards Bureau No. 3992

4. MANUFACTURER WARRANTY

APPLICATION

Reference

Mass fraction of free formaldehyde in ML-92 varnish is not more than 0.6%. APPLICATION. (Introduced additionally, Amendment No. 4).

INFORMATION DATA

State name

Name of the national standardization body

Republic of Azerbaijan Republic of Armenia Republic of Belarus Republic of Kazakhstan Kyrgyz Republic Republic of Moldova Russian Federation Republic of Tajikistan Turkmenistan Republic of Uzbekistan Ukraine

Azgosstandart

Armstate standard

Gosstandart of the Republic of Belarus Gosstandart of the Republic of Kazakhstan Kyrgyzstandart Moldovastandart Gosstandart of Russia Tajikstandart

Main State Service "Turkmenstandartlary"

Uzgosstandart

State Standard of Ukraine

3. INTRODUCED FOR THE FIRST TIME

4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

			Number of section, paragraph, subparagraph
GOST 12.1.004-91		GOST 8420-74
GOST 12.1.005-88		GOST 8832-76
GOST 12.1.044-89		GOST 8865-93	Introduction
GOST 12.3.005-75		GOST 8981-78
GOST 12.4.004-74		GOST 9410-78
GOST 12.4.009-83		GOST 9880-76
GOST 12.4.011-89		GOST 9949-76
GOST 12.4.021-75		GOST 9980.1-86
GOST 12.4.028-76		GOST 9980.2-86
GOST 12.4.068-79		GOST 9980.3-86
GOST 12.4.103-83		GOST 9980.4-2002
GOST 17.2.3.02-78		GOST 9980.5-86
		GOST 10315-75
GOST 2768-84		GOST 12026-76
GOST 3134-78		GOST 13526-79	1.1, 2.10, 2.11, 2.12,
GOST 3722-81
GOST 5233-89	1.1, 2.13.1, 2.13.2.4	GOST 14710-78
GOST 6433.1-71		GOST 17269-71
GOST 6433.2-71		GOST 17537-72
GOST 6433.3-71		GOST 19007-73
GOST 6806-73		GOST 19433-88

5. The limitation of the validity period was removed according to the protocol No. 4-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 4-94)

6. EDITION (March 2003) with Amendments No. 1, 2, 3, 4, 5 approved in October 1975, March 1980, June 1984, November 1988, May 2002 (IUS 12-75, 5-80, 10-84, 2-89, 8-2002)

Editor V.N. Kopysov Technical editor V.N. Prusakova Proofreader M.V. Buchnaya Computer layout E.N. Martemyanova

Ed. persons. No. 02354 dated 07/14/2000. Handed over to the set 03/25/2003. Signed for publication on May 23, 2003. Uel. oven l. 0.93. Uch.-ed. l. 0.80. Circulation 250 copies. From 10649. Order. 435.

IPK Publishing house of standards, 107076 Moscow, Kolodezny per., 14. e-mail:

Typed at the Publishing House on a PC

Branch of IPK Publishing house of standards - type. "Moscow printer", 105062 Moscow, Lyalin per., 6.

This standard applies to electrical insulating varnish ML-92, which is a solution of a mixture of glyptal varnish and melamine-formaldehyde resin K-421-02 in organic solvents.
Lacquer ML-92 is intended for impregnation of windings of electrical machines, devices and transformers and for coating electrical insulating parts.

Designation:	GOST 15865-70*
Russian name:	Electrical insulating varnish ML-92. Specifications
Status:	current (Introduced for the first time)
Text update date:	01.10.2008
Date added to database:	01.02.2009
Date of entry into force:	01.01.1971
Designed by:	USSR Ministry of Chemical Industry
Approved:	State Standard of the USSR (15.04.1970)
Published:	IPK Standards Publishing House No. 2003

GOST 15865-70

INTERSTATE STANDARD

ELECTRIC INSULATING VARNISHML-92

TECHNICAL CONDITIONS

IPK STANDARDS PUBLISHING HOUSE

Moscow

INTERSTATE STANDARD

Introduction date 01.01.71

This standard applies to electrical insulating varnish ML-92, which is a solution of a mixture of glyptal varnish and amino-formaldehyde resin K-421-02 in organic solvents.

Lacquer ML-92 is intended for impregnation of windings of electrical machines, devices and transformers and for coating electrical insulating parts. Lacquer ML-92 has a heat resistance class B according to GOST 8865.

Mandatory requirements aimed at ensuring the safety of the ML-92 varnish for the life, health and property of citizens, environmental protection are set out in paragraphs. (table, indicators 4, 12, 13), , .

(Changed edition, Rev. No. 4, 5).

1. TECHNICAL REQUIREMENTS

2.13.1. The hardness of the varnish coating is determined by GOST 5233, sec. 1 .

2.13.2. Determination of the hardness of the coating using a pendulum device type M-3.

2.13.2.1. Equipment and materials

Pendulum device type M-3 for determining hardness at room temperature (20 ± 2) ° C (drawing).

The main characteristics of the pendulum device:

Pendulum mass (120 ± 1) g;

The length of the pendulum, counting from the point of support to the end of the arrow, (500 ± 1) mm;

Steel ball diameter (support point) 7.938 mm according to GOST 3722;

Instrument scale divided into degrees;

Angle of deviation from 5 to 2°;

Decay time of oscillations on a glass plate (“glass number”) (440 ± 6) s.

Glass plates size 90´ 120 mm, thickness from 1.2 to 1.8 mm.

Stopwatch.

Solvents: ethyl ether according to GOST8981 or technical acetone according to GOST 2768.

1 - starting mechanism; 2 -base; 3 - scale; 4 - set screws; 5 - cargo; 6 - two-pointer mechanism; 7 - tripod; 8 - connecting strip; 9 - frame; 10 - table; 11 - steel balls; 12- plumb line

2.13.2.2. Preparing for the test

Before each test, the pendulum support balls and the glass plate of the instrument are carefully wiped with cotton soaked in solvent, and then with dry, clean gauze.

The plates prepared according to GOST 8832, the tested varnish is applied according to GOST 13526, kept at a temperature of (20 ± 2) ° C for 15 - 20 minutes and dried at a temperature of 115 - 120 ° C for 6 hours.

2.13.2.3 Testing

The pendulum device is checked by the "glass number" - the decay time of the pendulum oscillations, the fulcrum of which lies on the glass plate of the device.

The determination of the "glass number" is carried out at a temperature of (20 ± 2) ° C and relative air humidity (65 ± 5)%.

Measurements are carried out on at least three areas of the surface of the glass plate. In the same way, the decay time of the pendulum oscillations on a glass plate with a lacquer coating is determined.

2.13.2.4. Results processing

Hardness (H) conventional units, calculated by the formula

Where t is the damping time of the pendulum oscillations on the tested lacquer coating, s;

t 1 is the damping time of the pendulum oscillations on the glass plate of the instrument (“glass number”), s.

The test result is taken as the arithmetic mean of the results of measuring the decay time of the pendulum oscillations on the glass plate of the device and on the tested sample of the varnish coating.

Deviations of the values ​​of individual measurements from the arithmetic mean should not be more than 3%.

In case of disagreement, the “coating hardness” indicator is determined according to GOST 5233 using a TML-type pendulum device (pendulum A).

2.13.2.5 Method error

The error of the method in determining the hardness on the device M-3 is ± 0.02 conventional units.

2.13.1 -2.13.2.5. (Introduced additionally, Amendment No. 5).

2.14. The oil resistance of a varnish film is determined by GOST 13526on plates of soft copper tape with a thickness of 0.1 mm according to regulatory documentation. Lacquer application and intermediate drying are carried out according to paragraph . Then the plates with applied varnish are dried at 115 - 120° From within 6 h.

(Changed edition, Rev. No. 5).

2.15. Electrical strength and volume electrical resistivity are determined on plates made of cold-rolled copper sheet ( GOST 495) size 100´ 100 mm, thickness 0.4 - 0.6 mm. Lacquer is applied and dried according to p. .

The determination of the electrical strength is carried out on two plates of volumetric electrical resistance on at least three samples.

The electrical strength is determined using copper electrodes, the diameter of the upper electrode should be 25 mm. Stainless steel electrodes are allowed.

When determining the specific volumetric electrical resistance, measuring and guard electrodes are used in the form of aluminum foil ground to the surface of the sample.

The electrical strength is measured with a smooth rise in voltage at such a rate that the breakdown occurs in the range from 10 to 20 s after the start of the rise in voltage. When determining the specific volumetric electrical resistance, samples that have not been exposed to media and elevated temperatures are tested at voltages of 100 - 500 V. After exposure to various media and at elevated temperatures, tests are carried out at voltages of 100 - 250 V.

Conditions for normalization, conditioning and testing of electrical strength and volumetric electrical resistance:

1 hour (20°C) 65%; M (15 - 35 ° C) 45 - 75%;

1 hour (20°C) 65%; M (130 °С)< 20 %;

1 hour (20°C) 65% + 24 hours [(23.0 ± 0.5)°C] distilled water;

M (15-35°C) 45-75%.

(Changed edition, Rev. No. 3, 4).

3. PACKAGING, MARKING, TRANSPORTATION AND STORAGE

3.1. Packing - according to GOST9980.3.

(Changed edition, Rev. No. 4).

3.2. Marking - according to GOST9980.4.

The transport container must be marked with a danger sign in accordance with GOST 19433 (class 3), classification code 3313, UN number 1263.

3.3. Transportation and storage of varnish - according to GOST 9980.5.

When stored, the conditional viscosity of the varnish increases from the norm according to the table. . When the varnish is diluted with a solvent to the norm in terms of "viscosity", the varnish must comply with the requirements of this standard.

3.2, 3.3. (Changed edition, Rev. No. 4, 5).

4. MANUFACTURER WARRANTY

4.1. The manufacturer guarantees the compliance of the varnish with the requirements of this standard, subject to the conditions of storage and transportation.

4.2. Warranty shelf life of varnish - 12 months from the date of manufacture.

4.1, 4.2. (Revised edition, Rev. No. 3).

APPLICATION

Reference

The mass fraction of free formaldehyde in the ML-92 varnish is not more than 0.6%.

APPLICATION.(Introduced additionally, Amendment No. 4).

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the USSR Ministry of Chemical Industry

2. APPROVED AND INTRODUCED BY Decree of the Committee of Standards, Measures and Measuring Instruments under the Council of Ministers of the USSR dated April 15, 1970 No. 513

Amendment No. 5 adopted by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 20 dated 01.11.2001)

Registered by IGU Standards Bureau No. 3992

State name	Name of the national standardization body
The Republic of Azerbaijan	Azgosstandart
Republic of Armenia	Armstate standard
Republic of Belarus	State Standard of the Republic of Belarus
The Republic of Kazakhstan	State Standard of the Republic of Kazakhstan
Republic of Kyrgyzstan	Kyrgyzstandart
The Republic of Moldova	Moldovastandard
Russian Federation	Gosstandart of Russia

Electrical insulating varnishML-92issued according toGOST 15865-70

Appointment of electrical insulating varnishML-92

For impregnating windings of electrical machines, apparatus and transformers and for coating electrical insulating parts.

Compoundelectrical insulating varnishML-92

Varnish ML-92 is a solution of a mixture of glyptal varnish and melamine-formaldehyde resin K-421-2 in organic solvents.

Properties of electrical insulating varnishML-92

Lacquer ML-92, by its primary purpose, refers to materials that are exposed to electrical voltages, currents, electric arcs and surface discharges and has a heat resistance class B according to GOST 8865, which corresponds to a temperature of 130 ° C. Products coated with varnish can be used in conditions of moderate and tropical climate both indoors and under a canopy or in rooms (volumes), where fluctuations in temperature and humidity do not differ significantly from fluctuations in the open air and there is relatively free access to outdoor air. Temperature range of application of ML-92 lacquer is from minus 60 ° C to + 120 ° C.

Specifications electrical insulating varnish ML-92
Film appearance	glossy uniform smooth film from light brown to dark brown
Relative viscosity according to the VZ-246 viscometer with a nozzle diameter of 4 mm at a temperature of (20.0 ± 0.5) °C, s	25-50
Mass fraction of non-volatile substances,% C, s	50-55
Drying time up to degree 3 at a temperature of (105 -110) ° C, h, no more	1
Dielectric strength of the film, MV/m, not less than at (20 ± 2) °C	70 40 30
Ability to dry varnish in a thick layer at a temperature of (115-120) °C, h, no more	16
The hardness of the film according to the pendulum device M-3, arb. units, not less than	0,40
Specific volume electrical resistance of the film, Ohm x m, not less than at (20 ± 2) °C at (130 ± 2) °C after exposure to water for 24 h at (20 ± 2) °C	1∙10 12 1∙10 9 5∙10 10

Color solutionsvarnishML-92

After drying varnish ML-92 forms a surface from light brown to dark brown.

StoragevarnishML-92

Warranty period of storage of varnish - 12 months from the date of manufacture.

Lacquer ML-92 is stored in a tightly closed container, protected from moisture, heat and direct sunlight at temperatures from minus 40 ° C to +40 ° C.

Life timevarnishML-92

Subject to the requirements for surface preparation, application of materials and drying of coatings, it is allowed to apply varnish ML-92 on aluminum alloys without preliminary priming; operation of coatings in areas with a temperate and tropical climate. This ensures the electrical insulating properties of the coating.

Packing

Packing of electrical insulating varnish ML-92 is made in a special industrial container, taking into account all the requirements of the consumer.

Categories

ML-92, varnish, electrical insulation, aluminum, weather resistance, transformers, electrical machines

ApplicationvarnishML-92

Electrical insulating varnish ML-92 is impregnated with windings of electrical machines, apparatus and transformers, electrical insulating parts are coated with it, applied by dipping or pouring in 1-2 layers.

If necessary, ML-92 varnish is diluted with xylene, toluene or a mixture of one of these solvents with white spirit in a ratio of 3:1. The thickness of a single-layer varnish coating is from 20 to 30 microns.

The first layer of varnish before repeated dipping and the second layer of varnish before hot drying is kept at a temperature of (20 ± 2) ° C for 15 - 20 minutes. Then dried at a temperature of (105 - 110) ° C for 1 hour.

In a thick layer, the varnish dries at a temperature of 120°C for 16 hours.

Consumption for a single-layer varnish coating from 40 to 48 g/m 2 .

Precautionary measures

When carrying out work with ML-92 varnish, as well as after their completion, it is necessary to thoroughly ventilate the room. Use rubber gloves to protect your hands. Keep away from fire!

The main advantages of electrical insulating varnishML-92

Lacquer ML-92 refers to materials that are exposed to electrical voltages, currents, electric arcs and surface discharges;

Lacquer ML-92 has high electrical insulating properties;

Products treated with ML-92 lacquer are used in various climatic zones, withstanding high temperatures (up to 130°C).

GOST 15865-70

INTERSTATE STANDARD

ELECTRIC INSULATING VARNISH ML-92

TECHNICAL CONDITIONS

IPK STANDARDS PUBLISHING HOUSE

INTERSTATE STANDARD

Introduction date 01.01.71

This standard applies to electrical insulating varnish ML-92, which is a solution of a mixture of glyptal varnish and melamine-formaldehyde resin K-421-02 in organic solvents. Lacquer ML-92 is intended for impregnation of windings of electrical machines, devices and transformers and for coating electrical insulating parts. Varnish ML-92 has a heat resistance class B according to GOST 8865. Mandatory requirements aimed at ensuring the safety of ML-92 varnish for the life, health and property of citizens, environmental protection are set out in paragraphs. 1.1 (Table 1, indicators 4, 12, 13), 3.1, 3.2. (Changed edition, Rev. No. 4, 5).

1. TECHNICAL REQUIREMENTS

1.1. According to the physicochemical and electrical parameters, the ML-92 varnish must comply with the requirements and standards specified in Table. 1 .

Table 1

Name of indicator		Test method
1. The presence of mechanical inclusions in the varnish	Absence	According to GOST 13526
2. Appearance of the coating	After drying, the varnish should form a glossy smooth, uniform surface in color from light brown to dark brown.	According to clause 2.5
3. Relative viscosity according to a VZ-246 type viscometer with a nozzle diameter of 4 mm at a temperature of (20.0 ± 0.5) °C, s		According to GOST 8420
4. Mass fraction of non-volatile substances in varnish,%		According to GOST 17537 and clause 2.7 of this standard
5. Acid number, mg KOH, no more		According to GOST 13526
6. (Deleted, Rev. No. 4).
7. Drying time to degree 3 at a temperature of 105 - 110 ° C, h, no more		According to GOST 19007 and clause 2.10 of this standard
8. The ability to dry the varnish in a thick layer at a temperature of 115 - 120 ° C, h, no more		According to GOST 13526 and clause 2.11 of this standard
9. Thermoelasticity of the film at a temperature of (150 ± 2) ° С, h, not less		According to GOST 13526 and clause 2.12 of this standard
10. The hardness of the coating according to the pendulum device at a temperature of (20 ± 2) °С, not less than:		According to GOST 5233 and clause 2.13.2.2 of this standard
type TML (pendulum A), relative units
or type M-3, conventional units		According to clause 2.13
11. Film oil resistance, H, at least		According to GOST 13526 and clause 2.14 of this standard
12. Dielectric strength of the film, MV/m, not less than:		According to GOST 6433.3, GOST 13526, GOST 6433.1, GOST 10315 and according to clause 2.15 of this standard
at a temperature of (20 ± 2) ° С
after the action of water for 24 h at a temperature of (20 ± 2) ° C
13. Specific volumetric electrical resistance of the film, Ohm × m, not less than:		According to GOST 6433.2, GOST 13526, GOST 6433.1, GOST 10315 and clause 2.15 of this standard
at a temperature of (20 ± 2) °С
at a temperature of (130 ± 2) °С
after exposure to water for 24 hours at a temperature of (20 ± 2) °C

(Changed edition, Rev. No. 3, 4, 5). 1.2. Lacquer ML-92 must be produced in accordance with the requirements of this standard according to the recipe and technological regulations approved in the prescribed manner. (Revised edition, Rev. No. 2). 1.3. (Deleted, Rev. No. 2). 1.4. If necessary, before use, the varnish is diluted to working viscosity with toluene (GOST 14710 or GOST 9880), xylene (GOST 9949 or GOST 9410) or a mixture of one of these solvents with white spirit (nefras-C4-155/200) (GOST 3134) in ratio of at least 3:1. (Revised edition, Rev. No. 4). 1.5. 1.6. (Deleted, Rev. No. 2). 1a. Security requirements 1a.1. Lacquer ML-92 is a flammable and toxic material, due to the properties of the components that make up its composition. Maximum permissible concentrations, hazard classes of components according to GOST 12.1.005 and fire hazard characteristics according to GOST 12.1.044 are given in Table. 2.

table 2

Component name	Maximum permissible concentration of vapors in the air of the working area of ​​industrial premises, mg / m 3	Hazard Class	Temperature, °C		Concentration limits of ignition, % (by volume)
				self-ignition
xylene			At least 23
Solvent
White Spirit			At least 33
Toluene

* Lower flammable limit at 25°C and 101325 Pa (760 mm Hg). 1a.2. Possible routes of entry of harmful substances into the human body are inhalation and through the skin. Solvent vapors at high concentrations in the air irritate the mucous membranes of the eyes, upper respiratory tract and skin. 1a.3. The production of varnish must comply with the safety rules of paint and varnish production, approved in the prescribed manner. 1a.4. Production, testing and application of varnish must comply with GOST 12.3.005 and GOST 12.1.004. 1a.5. Persons associated with the manufacture and use of varnish must be provided with special clothing in accordance with GOST 12.4.103 and personal protective equipment in accordance with GOST 12.4.011, GOST 12.4.068. Individual means of respiratory protection against solvent vapors - according to GOST 12.4.028, GOST 12.4.004 and GOST 17269. 1a.6. Works related to the manufacture and use of varnish are carried out in rooms equipped with supply and exhaust and local ventilation in accordance with GOST 12.4.021, which ensures the state of the air environment in accordance with GOST 12.1.005. Fire extinguishers - sand, felt, foam fire extinguishers OHP-10, carbon dioxide OU-2 and OU-5, water mist, foam installations - according to GOST 12.4.009. 1a.7. To protect atmospheric air from pollution, air purification at gas treatment plants and control over compliance with maximum allowable emissions (MAE) in accordance with GOST 17.2.3.02 should be provided. 1a.8. Waste generated during the cleaning of equipment is disposed of in accordance with the procedure for the accumulation, transportation, neutralization and disposal of toxic industrial waste. Sec. 1a. (Revised edition, Rev. No. 5).

1b. ACCEPTANCE RULES

1b.1. Acceptance rules - according to GOST 9980.1. (Changed edition, Rev. No. 2, 4). 1b.2. Acceptance tests are carried out according to indicators 1 - 7, 10, 12, 13 of the table. 1. Upon receipt of unsatisfactory results of acceptance tests for at least one of the indicators, repeated tests are carried out on a double sample taken from the same batch. The test results apply to the entire batch. Norms for indicators 8, 9 table. 1 is determined periodically in every tenth batch. The rate for indicator 11 is determined at least once a year from the calendar date of the beginning of the release of varnish. Upon receipt of unsatisfactory results of periodic tests, each lot is checked until satisfactory results are obtained in a row at least on three lots. Upon receipt of a repeated negative result, periodic tests are transferred to acceptance tests until satisfactory results are obtained. (Revised edition, Rev. No. 5). 1b.3. (Deleted, Rev. No. 5).

2. TEST METHODS

2.1, 2.2. (Deleted, Rev. No. 2). 2.3. Sampling - according to GOST 9980.2. (Changed edition, Rev. No. 3, 4). 2.3a. Indicators - the appearance of the coating, the relative viscosity according to the VZ-246 (or VZ-4) viscometer, the mass fraction of non-volatile substances, the acid number, the ability to dry out in a thick layer - are determined in undiluted varnish. (Changed edition, Rev. No. 3, 4, 5). 2.4. (Deleted, Rev. No. 3). 2.5. The appearance of the varnish coating is determined visually in natural diffused light. The lacquer is applied in bulk in one layer with an initial viscosity of 25–50 s on a clean glass plate 90 ´ 120 mm in size, 1.2 to 1.8 mm thick. The plate is placed at an angle of 45 ° in a place protected from dust and kept at a temperature of (20 ± 2) ° C for 15 - 20 minutes, then dried at a temperature of 105 - 110 ° C for 1 hour. After cooling, consider the varnish coating. (Revised edition, Rev. No. 5). 2.6. (Deleted, Rev. No. 4). 2.7. To determine the mass fraction of non-volatile substances in varnish, a sample of varnish weighing 1.5 - 2 g is placed in an oven and kept at a temperature of (120 ± 2) ° C for 1 hour (Changed edition, Amendment No. 3). 2.8. (Deleted, Rev. No. 3). 2.9 - 2.9.2. (Deleted, Rev. No. 4). 2.10. The drying time of the varnish film is determined in accordance with GOST 19007 on plates of soft copper tape 0.1 mm thick according to regulatory documentation. The varnish is applied according to GOST 13526. The first layer of varnish before repeated dipping and the second layer of varnish before hot drying is kept at (20 ± 2) °C for 15 - 20 minutes. Then the lacquered plates are dried at 105 - 110 °C for 1 hour (Revised edition, Amendment No. 5). 2.11. The ability to dry the varnish in a thick layer is determined according to GOST 13526 at a temperature of 115 - 120 ° C for 16 hours. Before hot drying, the boxes with varnish are kept at (20 ± 2) ° C for 30 minutes. The condition of the sample after heat treatment must comply with SI U -2-1 (3-4) 2. The drying of the lower surface of the sample after its curing is checked as follows: a sheet of filter paper (GOST 12026) of a square shape is applied to each sample, turned upside down. side 24 - 25 mm, on top of which a rubber disk with a diameter of 22 mm and a thickness of 5 mm is placed, and then a cylindrical load weighing 500 g. After 1 min, the sample is checked for compliance with the requirements of Table. 3 GOST 13526. (Changed edition, Rev. No. 3, 4, 5). 2.12. The thermoelasticity of the lacquer film is determined according to GOST 13526 on plates of soft copper tape 0.1 mm thick according to regulatory documentation. The varnish is applied and dried according to clause 2.10, while the second layer of varnish is dried at 115 - 120 ° C for 1 hour. Then the plates are kept in a thermostat at a temperature of (150 ± 2) ° C for 48 hours. The samples are removed from the thermostat, cooled to (20 ± 2) °C and tested in accordance with GOST 6806 around a rod with a diameter of 3 mm. (Changed edition, Rev. No. 3, 5). 2.13. Determination of coating hardness (Revised edition, Rev. No. 5). 2.13.1. The hardness of the varnish coating is determined according to GOST 5233, sec. 1. 2.13.2. Determination of coating hardness by pendulum device type M-3. 2.13.2.1. Equipment and materials Pendulum device type M-3 for determining hardness at room temperature (20 ± 2) °C (drawing). The main characteristics of the pendulum device: - mass of the pendulum (120 ± 1) g; - the length of the pendulum, counting from the fulcrum to the end of the arrow, (500 ± 1) mm; - steel ball diameter (support point) 7.938 mm according to GOST 3722; - scale of the device, divided into degrees; - deviation angle from 5 to 2°; - damping time of oscillations on a glass plate ("glass number") (440 ± 6) s. Glass plates 90 ´ 120 mm in size, 1.2 to 1.8 mm thick. Stopwatch. Solvents: ethyl ether according to GOST 8981 or technical acetone according to GOST 2768. 1 - starting mechanism; 2 - base; 3 - scale; 4 - set screws; 5 - cargo; 6 - two-pointer mechanism; 7 - tripod; 8 - connecting strip; 9 - frame; 10 - table; 11 - steel balls; 12 - plumb line 2.13.2.2. Preparation for the test Before each test, the pendulum support balls and the glass plate of the device are carefully wiped with cotton wool moistened with a solvent, and then with dry, clean gauze. On plates prepared in accordance with GOST 8832, the test varnish is applied in accordance with GOST 13526, kept at a temperature of (20 ± 2) ° C for 15 - 20 minutes and dried at a temperature of 115 - 120 ° C for 6 hours. 2.13.2.3. Testing The pendulum device is checked by the "glass number" - the decay time of the pendulum oscillations, the fulcrum of which lies on the glass plate of the device. The determination of the "glass number" is carried out at a temperature of (20 ± 2) °C and relative air humidity (65 ± 5)%. Measurements are carried out on at least three areas of the surface of the glass plate. In the same way, the decay time of the pendulum oscillations on a glass plate with a lacquer coating is determined. 2.13.2.4. Processing results Hardness (H) conventional units, calculated by the formula

Where t is the damping time of the pendulum oscillations on the tested lacquer coating, s; t 1 is the damping time of the pendulum oscillations on the glass plate of the instrument (“glass number”), s. The test result is taken as the arithmetic mean of the results of measuring the decay time of the pendulum oscillations on the glass plate of the device and on the tested sample of the varnish coating. Deviations of the values ​​of individual measurements from the arithmetic mean should not be more than 3%. In case of disagreement, the “coating hardness” indicator is determined according to GOST 5233 using a TML-type pendulum device (pendulum A). 2.13.2.5. Error of the method The error of the method in determining the hardness on the device M-3 is ± 0.02 conventional units. 2.13.1 - 2.13.2.5. (Introduced additionally, Amendment No. 5). 2.14. The oil resistance of the lacquer film is determined according to GOST 13526 on plates of soft copper tape 0.1 mm thick according to regulatory documentation. Applying varnish and intermediate drying is carried out according to clause 2.10. Then the varnished plates are dried at 115 - 120 ° C for 6 hours (Changed edition, Rev. No. 5). 2.15. The electrical strength and volumetric electrical resistivity are determined on plates made of cold-rolled copper sheet (GOST 495) 100 ´ 100 mm in size, 0.4 - 0.6 mm thick. The varnish is applied and dried according to clause 2.14. The determination of electrical strength is carried out on two plates of volumetric electrical resistance on at least three samples. The electrical strength is determined using copper electrodes, the diameter of the upper electrode should be 25 mm. Use of electrodes from stainless steel is allowed. When determining the specific volumetric electrical resistance, measuring and guard electrodes are used in the form of aluminum foil ground to the surface of the sample. The dielectric strength is measured with a gradual rise in voltage at such a rate that breakdown occurs in the range from 10 to 20 s after the start of the voltage rise. When determining the specific volumetric electrical resistance, samples that have not been exposed to media and elevated temperatures are tested at voltages of 100–500 V. After exposure to various media and at elevated temperatures, tests are carried out at voltages of 100–250 V. Conditions for normalization, conditioning and testing of electrical strength and specific volume electrical resistance: 1 h (20 °C) 65%; M (15 - 35 ° C) 45 - 75%; 1 hour (20 °C) 65%; M (130 °С)< 20 %; 1 ч (20 °С) 65 % + 24 ч [(23,0 ± 0,5) °С] дистиллированная вода; М (15-35°С) 45-75 %. (Измененная редакция, Изм. № 3, 4).

3. PACKAGING, LABELING, TRANSPORT AND STORAGE

3.1. Packing - in accordance with GOST 9980.3. (Revised edition, Rev. No. 4). 3.2. Marking - according to GOST 9980.4. The transport container must be marked with a danger sign in accordance with GOST 19433 (class 3), classification code 3313, UN number 1263. 3.3. Transportation and storage of varnish - in accordance with GOST 9980.5. During storage, the relative viscosity of the varnish increases from the norm according to the table. 1. When diluting the varnish with a solvent to the norm in terms of "viscosity", the varnish must comply with the requirements of this standard. 3.2, 3.3. (Changed edition, Rev. No. 4, 5).

4. MANUFACTURER WARRANTY

4.1. The manufacturer guarantees the conformity of the varnish with the requirements of this standard, subject to the storage and transportation conditions. 4.2. Warranty period of storage of varnish - 12 months from the date of manufacture. 4.1, 4.2. (Revised edition, Rev. No. 3).

APPLICATION

Reference

Mass fraction of free formaldehyde in ML-92 varnish is not more than 0.6%. APPLICATION.(Introduced additionally, Amendment No. 4).

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Chemical Industry of the USSR 2. APPROVED AND INTRODUCED BY Decree of the Committee of Standards, Measures and Measuring Instruments under the Council of Ministers of the USSR dated April 15, 70 No. 513 Change No. 5 was adopted by the Interstate Council for Standardization, Metrology and Certification (minutes No. 20 dated November 1 .2001) Registered by the IGU Standards Bureau No. 3992 The following voted for the adoption of the change:

State name	Name of the national standardization body
The Republic of Azerbaijan	Azgosstandart
Republic of Armenia	Armstate standard
Republic of Belarus	State Standard of the Republic of Belarus
The Republic of Kazakhstan	State Standard of the Republic of Kazakhstan
Republic of Kyrgyzstan	Kyrgyzstandart
The Republic of Moldova	Moldovastandard
Russian Federation	Gosstandart of Russia
The Republic of Tajikistan	Tajikstandart
Turkmenistan	Main State Service "Turkmenstandartlary"
The Republic of Uzbekistan	Uzgosstandart
Ukraine	State Standard of Ukraine

3. INTRODUCED FOR THE FIRST TIME 4. REFERENCE REGULATIONS AND TECHNICAL DOCUMENTS

			Number of section, paragraph, subparagraph
GOST 12.1.004-91	1a.4	GOST 8420-74	1.1
GOST 12.1.005-88	la.l, la.6	GOST 8832-76	2.13.2.2
GOST 12.1.044-89	1a.1	GOST 8865-93	Introduction
GOST 12.3.005-75	1a.4	GOST 8981-78	2.13.2.1
GOST 12.4.004-74	1a.5	GOST 9410-78	1.4
GOST 12.4.009-83	la .6	GOST 9880-76	1.4
GOST 12.4.011-89	1a.5	GOST 9949-76	1.4
GOST 12.4.021-75	la .6	GOST 9980.1-86	1b.1
GOST 12.4.028-76	1a.5	GOST 9980.2-86	2.3
GOST 12.4.068-79	1a.5	GOST 9980.3-86	3.1
GOST 12.4.103-83	1a.5	GOST 9980.4-2002	3.2
GOST 17.2.3.02-78	1a.7	GOST 9980.5-86	3.3
GOST 495-92	2.15	GOST 10315-75	1.1
GOST 2768-84	2.13.2.1	GOST 12026-76	2.11
GOST 3134-78	1.4	GOST 13526-79	1.1 , 2.10, 2.11, 2.12, 2.13.2.2, 2.14
GOST 3722-81	2.13.2.1	GOST 14710-78	1.4
GOST 5233-89	1.1 , 2.13.1, 2.13.2.4	GOST 17269-71	1a.5
GOST 6433.1-71	1.1	GOST 17537-72	1.1
GOST 6433.2-71	1.1	GOST 19007-73	1.1 , 2.10
GOST 6433.3-71	1.1	GOST 19433-88	3.2
GOST 6806-73	2.12

5. The validity period was removed according to the protocol No. 4-93 of the Interstate Council for Standardization, Metrology and Certification (IUS 4-94) 6. EDITION (March 2003) with Amendments No. 1, 2, 3, 4, 5 approved in October 1975, March 1980, June 1984, November 1988, May 2002 (IUS 12-75, 5-80, 10-84, 2-89, 8-2002)

All paints and varnishes with electrical insulating qualities can be divided into the following groups: impregnating, coating, gluing. For example, electrical insulating varnish ML 92, No. 318 and a number of others are used more as a protective impregnation. In addition, ML 92 and 318 are used to process the windings of electrical machines, apparatus, transformers, individual electrical insulating parts.

purpose

1. Impregnation. They are used as a connecting means of winding turns among themselves, including to reduce porosity in the winding insulation. The solution, penetrating into the pores, fills the space, thereby giving the elements water-repellent properties. Increases electrical insulation strength, improves electrical conductivity.
2. Integumentary. They are used as an additional protective coating on already impregnated moisture-resistant or oil-resistant surfaces. Solutions of this nature are still used to insulate sheets of electrical steel in magnetic circuits.
3. Adhesive. From the name of the group, the main purpose of the substances becomes clear - gluing together individual electrical insulating elements, for example, mica leaves, ceramics, plastics, and so on. One of the important characteristics is the high adhesive properties of the solution.

Despite such a strict division into groups, almost all of these solutions can be used to perform two tasks at once, for example, impregnation and coating.

The classification of electrical insulating varnishes includes distribution not only by purpose, but also by other parameters:

• according to the method of drying: cold (in natural conditions) and hot (under the influence of high temperatures- more than 100 degrees Celsius);
• on the basis: resin, oil, oil-bitumen, ether-cellulose.

Characteristics of varnish ML 92

ML 92 with electrical insulating properties is a liquid mixture of glyptal varnish with the addition of melamine-formaldehyde resin. Organic solvents act as a diluent. Usually the solution is sold in a ready-to-use form. But to reduce the viscosity of the substance, dilution with toluene, xylene or a mixture of these substances with white spirit is allowed.

After polymerization, a shiny uniform protective film of a brownish tint is formed on the treated surface. The estimated consumption of the substance is 40-50 g per square meter. The polymerization time of a single-layer varnish is 60 minutes at a high temperature regime of +105-110. With multi-layer impregnation under the same drying conditions (or 10 degrees higher), curing will occur in about 16 hours.

Important technical characteristics of ML 92 are indicators of electrical strength and specific volumetric electrical resistance of the coating:

1. Electrical strength, MV/m:

• at + 18-22 ° С - from 70;
• at +128-132°С - from 40;
• after getting wet during the day at + 18-22 ° С - from 30;

1. Specific volume electrical resistance:

• at +18-22°С - from 1.E+12 Ohm.*m;
• at +128-132°С - from 1.E+9 Ohm.*m;
• after getting wet during the day at + 18-22 ° С - from 5.E + 10 Ohm.*m.

Due to the presence of volatile chemicals in the solution, you should follow the rules for working with the product and observe personal safety measures. Another precaution is elementary fire safety rules.

Composition and technical characteristics of varnish 318

Bituminous lacquer 318 forms a black protective film on the surface. It is used for impregnation during the repair of low voltage electrical machines. Contains organic solvents. Diluted with white spirit and solvent naphtha.

Of the obvious advantages of oil-bitumen varnish 318 with electrical insulating properties, the following should be highlighted:

• increased moisture resistance;
• heat resistance class A.

However, varnish 318 is weakly resistant to the influence of technical (transformer) oils, and is capable of dissolving.

Acrylic lacquer with insulating properties

If you are looking for a substance with high dielectric properties, you can try acrylic insulating varnish. It is also used for corrosion and weather protection of motor and transformer windings, as well as for printed circuit boards.

Dries pretty quickly. Forms a transparent protective film, strong enough and resistant to various influences. Of the undoubted advantages of the solution, we highlight:

• moisture resistance;
• dirt resistance;
• protection against oxidative reactions;
• chemical inertness;
• high dielectric abilities;
• wide operating temperature range - from -70°С to +100°С.

Electrical insulating varnishes and other similar means are needed in order to safely and efficiently use electrical equipment of various configurations.

Especially if such devices operate in automatic mode and perform important technological functions (in production, at home).