NB/T 10307-2019Defrost heater for refrigerator (English PDF)

3.1 Aluminum tube heater

The metal aluminum tube is used as the heat conductor, the high resistance electric heating alloy material is used as the heating body, and the silicon rubber is used as the insulating medium between the two.

The lead wire is connected to the power source for heating.

3.2 Sheet heater

The metal aluminum foil is used as the heat conductor, and the high-resistance electric heating alloy material is used as the heating element. Between the two, polyvinyl chloride, polytetrafluoroethylene, silicon rubber Glue or similar insulator is used as the insulating medium, and the two ends are connected to the power supply with lead wires for heating.

3.3 Tube heater

Use stainless steel as the shell, high-resistance electric heating alloy material as the heating element, and dense magnesium oxide powder or similar insulator between the two It is an insulating medium and is connected to the power supply through an extraction device for heating.

3.4 Heater

A component that converts electrical energy into heat.

3.5 Lead-out rod

The metal parts that have a good connection with the heating element are directly or through the plug-in piece, connecting piece, wire and other connecting devices connected to it and the electric The source is connected.

3.6 Lead-out device

The collective name of the lead rod and the inserts, connecting pieces, wires and other components connected to it.

3.7 Lead-out line

A wire that has a good connection with the heating element; connects to the power source directly or through a connecting piece connected to it.

3.8 Heating line

Use high-resistance electric heating alloy materials as heating elements, and use polyvinyl chloride, polytetrafluoroethylene, silicon rubber or similar insulators as insulating medium, A linear heating element with an insulating protective layer extruded by an extruder.

3.9 Effective heating length

The length of the effective heating part of the element heating element.

3.10 Effective heating surface

The surface of the metal tube and foil corresponding to the effective heating part of the component.

3.11 Surface effective load

The power per unit area on the effective heating surface of the component.

3.12 Normal operation

When the component is connected to the rated power supply, it is in the working state under normal use (conditions).

3.13 Working temperature

The average temperature of the effective heat-generating surface of the component when the rated power is input and in normal operation.

3.14 Simulation condition

Under the conditions stipulated in the various clauses of this standard, some measures shall be taken to make the average temperature of the heating surface of the element basically consistent with the working temperature Working conditions.

3.15 Damage

The component is considered damaged when one of the following conditions.

a) The electrical strength at the working temperature that the component can withstand is less than 75% of the normal specified value;

b) The leakage current at the operating temperature of the component is greater than 3.5 mA;

c) The insulation resistance of the component is lower than 2 Mohm;

d) Under normal working conditions, the input power of the component is lower than 80% of the rated power or higher than 120% of the rated power;

e) The pipe body produces flames, melts or other damage that cannot be repaired when the component is working.

3.16 Operation life

The cumulative working time of the component from working to damage under normal working conditions.

3.17 Equivalent resistance

The DC resistance of the component at operating temperature.

3.18 Heating medium

A carrier that directly absorbs heat from the component.

4.1 Classification

Defrost heaters are divided into three types. aluminum tube heaters, sheet heaters, and steel tube heaters according to material characteristics.

4.2 Main technical parameters

4.2.1 The main technical parameters and units involved in the components.

a) Power supply voltage, in volts (V);

b) Power frequency, in Hertz (Hz);

c) Rated voltage, in volts (V);

d) Rated power, in watts (W);

e) Working temperature, the unit is Kelvin (K) or Celsius (°C);

f) Outer diameter in millimeters (mm);

g) Dimensions in millimeters (mm);

h) Weight in kilograms (kg); i) Heating medium.

4.2.2 Calculation method of some technical parameters.

a) Surface payload The unit is watts per square centimeter (W/cm2).

Surface effective load calculation formula. surface effective load = power value of the component/effective heating surface area of the component

b) Equivalent resistance The unit is ohm (ohm).

4.3 Model naming

4.3.1 The model of the component is recommended to be named according to the rules specified in Figure 1 or Figure 2, or it can be named by the manufacturer.

The model should reflect the uniqueness of the electrical and mechanical characteristics, size and function of the component as much as possible.

4.3.2 The model representation method of aluminum tube and sheet heater is shown in Figure 1.

4.3.3 The model representation method of steel pipe heater is shown in Figure 2.

5.1 Basic requirements

5.1.1 The components should be able to comply with the provisions of this standard and be manufactured in accordance with product drawings and technical documents.

Note: Refer to Appendix B for the typical structure of components.

5.1.2 The components should work normally under the following conditions.

a) The relative humidity of the surrounding air is not more than 90% (when the temperature is 25 °C);

b) There is no obvious shock and vibration.

5.1.3 The resistance materials used in the components should meet the requirements of GB/T 1234.

5.2 Information required by the manufacturer

The component manufacturer shall provide sufficient information to ensure that the tests related to this standard can be carried out to confirm that the component meets the requirements of this standard.

The data required for component testing of this standard includes but is not limited to the provisions of Table 1.

5.3 Safety requirements

5.3.1 Power deviation

Under normal working conditions, the deviation of the input power of the component from the rated power should not be greater than the deviation shown in Table 2.

5.3.2 Leakage current

5.3.2.1 For steel pipe heaters used for defrosting, the leakage current at working temperature is not more than 0.75 mA.

5.3.2.2 For aluminum tubes and sheet heaters used for defrosting, the leakage current at working temperature shall not exceed 0.02 mA per meter.

5.3.3 Electric strength

The insulation of the component should be able to withstand the corresponding electric strength test, and there should be no breakdown during the test.

The test voltages corresponding to different rated voltages are shown in Table 3.

5.3.4 Insulation resistance

5.3.4.1 The cold insulation resistance value of the steel pipe heater used for defrosting shall not be less than 100 Mohm during the factory inspection; in the sealing test, overload energy The insulation resistance value after the force test and the life test should not be less than 5Mohm.

5.3.4.2 The cold insulation resistance value of aluminum tubes and sheet heaters used for defrosting shall not be less than 300Mohm during the factory inspection;

The insulation resistance value after overload capacity test and life test should not be less than 10Mohm.

5.3.5 Overload capacity

Under the specified conditions, the components should be able to withstand 30 cycles of overload test without damage.

--For components whose rated input power does not exceed 100 W, the input power of the overload test is 1.33 times the rated value;

--For components whose rated input power exceeds 100 W, the input power of the overload test is 1.27 times the rated value or 1.21 times plus 12 W, choose the larger of the two.

5.4 Hygiene requirements

The shells or coatings of components designed to be in contact with food and eating utensils should meet the requirements of relevant national health standards.

Unless the manufacturer declares this requirement, it is regarded as a component that is not in contact with food and eating utensils.

5.5 Requirements for hazardous substance limits

The content of hazardous substances in the components used in electronic information products should comply with the National Administration of Restriction of Use of Hazardous Substances in Electrical and Electronic Products Measures" and GB/T 26572.

Unless the manufacturer declares this requirement, it is deemed to be a component not used in electronic information products.

5.6 Performance requirements

5.6.1 Appearance

5.6.1.1 Steel pipe and aluminum pipe heaters shall not have significant mechanical scars or local expansion caused by abnormal processing and production.

5.6.1.2 There should be no wrinkles, bumps, cracks and cracks at the bend of the steel pipe and aluminum pipe heater. The diameter of the aluminum tube heater is greater than 5 The flatness rate of the bend is >=70% for the aluminum tube; the flatness rate of the bend is >=80% for the aluminum tube whose diameter is greater than 4 and less than or equal to 5.

5.6.1.3 The heating wires of the sheet heater should be neatly arranged and firmly bonded, and no virtual sticking phenomenon is allowed; the heat conductor should be flat, smooth, and colored There should be no damage and missing corners evenly.

5.6.1.4 The coating, electroplating layer, enamel layer, metal or non-metal spraying layer or aluminizing layer shall be uniform and firm, and there shall be no bubbles, peeling or localization. Department accumulation phenomenon.

5.6.2 General structure

5.6.2.1 Between the heating element of the steel tube heater and the lead wire (including the end), between the heating element of the aluminum tube heater (heating wire) and the lead wire (including the end)

(Including the end) between the heating element (heating wire) of the chip heater and the lead wire should be sealed (if there is an agreement, the end can be temporarily sealed It is not sealed, and the sealing performance is not assessed); the minimum bending radius of the sheet heater is >=5mm.

5.6.2.2 The length of the lead rod of the steel pipe heater in the pipe shall not be less than the value specified in Table 4.

If the cross-section of the component is irregular, its requirements for the geometric dimensions of the lead-out rod shall be assessed in accordance with the technical documents provided by the manufacturer.

5.6.2.3 The deviation of the outer diameter of the component should not exceed the value specified in Table 5.

5.6.2.4 The dimensional tolerances specified in this standard shall be evaluated according to the regulations, and the other dimensions with tolerance requirements shall be evaluated according to their requirements.

Note the size of the tolerance is evaluated according to the V level of GB/T 1804-2000.

5.6.3 Working temperature

The temperature of the pipe body during normal operation of the component should not exceed the limit that has been proven that the material can be used safely. The steel pipe used for defrosting is added The effective heating surface temperature of the tube body during normal operation of the heater should not exceed 394°C; the effective heating surface of the tube body during normal operation of the aluminum tube heater The temperature should not exceed 130°C; the effective heating surface temperature of the sheet heater during normal operation should not exceed 80°C.

5.6.4 Device requirements

5.6.4.1 The lead-out device of the steel pipe heater shall be able to withstand a tensile force of 70% of its own tensile force, but not more than 1,000 N and a tensile force that lasts for 3 minutes In the test, no displacement and fracture occurred. Do not use explosive force during the test.

5.6.4.2 The steel pipe heater is welded with the lead-out device of the lug, the tensile force value of the lug should be 200 N, the direction is axial, and it lasts 3 times.

In the tensile test of min, explosive force shall not be used during the test, and the welding piece shall not break or fall off during the test.

5.6.4.3 The aluminum tube, sheet heater heating element (heating wire) and the lead wire should be able to withstand a 36N tensile test for 60 s. After the test It should not break or fall off.

5.6.4.4 For components equipped with grounding blades, terminals and lead wires with connectors, the connectors shall comply with GB 17196-2017 connecting device connection Safety requirements for flat quick-connect terminals for copper wires.

5.6.4.5 The heating wire should be able to withstand a 36N tensile test that lasts for 60 s. After the test, its permanent growth rate shall not exceed 8%.

5.6.5 Working life

The power-on time of the component under normal working conditions should reach the usage time declared by the manufacturer.

It is judged by the test requirements of 6.11.1 and 6.11.2.

5.6.6 Flame resistance

The non-metallic parts such as the sealing material in the component should have corresponding flame resistance.

5.6.7 Peel strength

For chip components with hot melt adhesive, the bonding area between the heating wire and the aluminum foil should be able to withstand the adhesive peel strength test of 400 g.

5.6.8 Contact resistance

The contact resistance of components with grounding devices must not be greater than 10 mohm.

5.6.9 Corrosion resistance

5.6.9.1 After the salt spray test, the metal part of the steel pipe heater shall not have material corrosive pits that cannot be effectively removed (clean water and scouring pad) Abnormal spots and rust.

5.6.9.2 After the salt spray test, the aluminum tube and the sheet heater are allowed to appear oxide spots on the surface, but no obvious corrosive pits and corrosion are allowed. Powdered substance after etching.

5.6.10 Heat resistance

After the high temperature test according to 6.16, the insulation resistance and electric strength should meet the requirements of 5.3.3 and 5.3.4.

5.6.11 Cold resistance

After conducting the cold resistance test according to 6.17, the insulation resistance and electric strength should meet the requirements of 5.3.3 and 5.3.4.

6.1 General method of test

6.1.1 The relevant tests involving energization of components should be carried out under the following conditions.

a) The ambient temperature is 20 °C ± 5 °C, there is no wind and no strong radiation, the relative humidity is not more than 85% (when the temperature is 25 °C), the atmospheric environment The environment is below 2 000 m above sea level, or other conditions that meet the requirements of technical documents;

b) The allowable error of the power supply voltage does not exceed ±1%;

c) The components are installed in the appliance or under simulated conditions;

d) In all tests, the measuring instrument or measuring device should not significantly affect the measured value;

e) Unless otherwise specified, components with multiple rated voltages or one (multiple) rated voltage ranges shall be within the specified range The most unfavorable voltage is tested, and the upper limit (maximum) of the rated voltage range is generally defaulted as its most unfavorable voltage;

f) There should be no flammable and explosive materials and gases in the test site;

g) The test personnel should make appropriate safety protection, and should use appropriate devices to fix and protect the components to avoid the test process Due to high temperature or insufficient electrical protection, it may cause personal injury or damage the surrounding environment;

h) There should be no people frequently moving in the test site.

6.1.2 The accuracy or error of test instruments and meters shall meet the following requirements.

a) The accuracy of electrical measuring instruments used for type testing should not be less than 0.5; for ex-factory inspection, it should not be less than 1.0;

b) For temperature measuring instruments, the allowable relative error shall not exceed ±1%;

c) For instruments that measure time, the allowable error requirement does not exceed ±0.1 s;

d) For measuring tools for measuring length, the allowable relative error shall not exceed ±0.5%;

e) For instruments measuring humidity, the allowable relative humidity error shall not exceed ±1%.

6.2 Measurement of rated power

Make the component work under the rated voltage and normal state, when the input power is stable, measure the input power, the power deviation should conform to 5.3.1 Requirements.

6.3 Measurement of leakage current

6.3.1 Leakage current measurement at operating temperature

The component works under normal conditions, and the test voltage should be adjusted to make the input power equal to 1.15 times the maximum rated input power.

After setting the state, measure the leakage current. The measurement method is shown in 13.2 of GB 4706.1-2005. The measured result should meet the requirements of 5.3.2.

Note: Before the test of the tubular element, the moisture in the element is allowed to be drained.

6.3.2 Leakage current measurement after sealing test

The test should be carried out after the component is not connected to the power source and the sealing test is completed.

The test voltage is 1.06 times the rated voltage, and the leakage current is measured after the test voltage is applied for 10 minutes (after the power is stabilized). See the measurement method In 16.2 of GB 4706.1-2005, the measured result should meet the requirements of 5.3.2.

6.4 Electric strength test

6.4.1 Cold electric strength test

According to the provisions of 16.3 in GB 4706.1-2005. The component should withstand a basic sine wave with a duration of 1 min and a frequency of 50 Hz or 60 Hz The test voltage is determined according to Table 3. The setting current of the electric strength test equipment is 5 mA, and the test result should meet the requirements of 5.3.3.

6.4.2 Electric strength test at working temperature

Immediately after the test in 6.3.1, proceed in accordance with the provisions in 13.3 of GB 4706.1-2005, within 5 s. The components should endure for 1 min, The voltage of the basic sine wave with a frequency of 50 Hz or 60 Hz. The test voltage is determined according to Table 3. The setting current of the electric strength test equipment is 5 mA, the test result should meet the requirements of 5.3.3.

6.4.3 Electric strength test after sealing test

After the test in 6.7.2, the components shall be subjected to a voltage of a basic sine wave with a frequency of 50 Hz or 60 Hz for 1 min. The test voltage is based on Table 3 confirms that the setting current of the electric strength test equipment is 5 mA, and the test result should meet the requirements of 5.3.3.

6.5 Insulation resistance test

During the test, the element tube and the megger shall not form a loop through the earth. The megohmmeter should be connected between any lead-out device of the component and the pipe body.

Apply a test voltage of DC500 V to measure the insulation resistance, and measure the insulation resistance 1 min after applying the test voltage. The test result should meet the requirements of 5.3.4 begging.

6.6 Overl