How To Verify The Quality Of Electric Heating Elements
The intuitive way to verify the quality of the heating element is: first wipe the surface of the heating element, then switch on the AC 220V power supply, dry it in the air, turn off the power after the surface turns red, and wipe the heating element with a napkin after the heating element is completely cooled. There should be no black oxidizing powder on the paper (not reacting with oxygen in the air), indicating that it is a qualified electric heating element.
Performance requirements of electric heating elements
1.Heating time
Under the test voltage, the time for the component to rise from the ambient temperature to the test temperature should not exceed 15min
2. Deviation of rated power
Under the condition of sufficient heat generation, the deviation of the rated power of the component should not exceed the range specified below; for components with a rated power less than or equal to 100W: ±10%. For components with a rated power greater than 100W, it is +5%～-10% or 10W, whichever is greater.
3. Leakage current</DIV>
The leakage current in cold state and the leakage current after water pressure and sealing test shall not exceed 0.5mA, and the leakage current in hot state at working temperature shall not exceed the calculated value in the formula, but not exceed 5mA I=1/6 (tT×0.00001) When multiple components are connected in series to the power supply, the leakage current test should be performed on this group of components as a whole.
4. Insulation resistance
The cold insulation resistance during the factory inspection should not be less than 50MΩ. After the sealing test, the insulation resistance after long-term storage or use should not be less than MΩ, and the thermal insulation resistance at the working temperature should not be lower than the calculated value in the formula, R=“( 10-0.015T)/t”×0.001
5. Insulation compressive strength
The component should be kept under the specified test conditions and test voltage for 1 min without flashover and breakdown.
6. Ability to withstand power on and off
The component should be able to undergo 2000 power-on and power-off tests under the specified test conditions without damage.
7. Overload capacity
The component should withstand 30 cycles of overload test under the specified test conditions and input power without damage.
8. Heat resistance
The component should withstand 1000 cycles of heat resistance test under the specified test conditions and test voltage without damage
