The main factors affecting the insulation resistance of electric heaters

The main factors affecting the insulation resistance of electric heaters

Including the quality of insulation materials, production process control, sealing materials and sealing processes.

Under normal circumstances, the cold insulation resistance value should not be less than 50M Ω and 100% testing is required; The thermal insulation resistance value should not be less than 1M Ω and should be tested as a sampling item if necessary; The insulation resistance value of the electric heater after sealing test, long-term storage or use should not be less than 1M Ω.

Electrical strength (withstand voltage)

When a certain test voltage is applied between the live and non live parts of an electric heater according to the standard and continues for a specified time, the high voltage at which the product does not experience breakdown is called electrical strength (hereinafter referred to as withstand voltage). Voltage resistance is an important parameter indicating the safety performance of electric heaters. Pressure resistance is generally divided into cold state pressure resistance and hot state pressure resistance.

Test method for withstand voltage

·Cold state withstand voltage test: In the absence of power, place the tested component in a constant temperature and humidity environment for stable 24 hours, and then conduct the test.

·Hot state withstand voltage test: Load current to reach the operating temperature of the electric heater and stabilize it before powering off. Conduct the test within 5 seconds after powering off. No method of forcibly cooling the components is allowed within these 5 seconds.

The main factors affecting the voltage resistance of electric heaters

Including the quality of insulation materials and the thickness of insulation layers, production process control, sealing materials and sealing processes.

Under normal circumstances, 100% testing is required for cold withstand voltage; Hot state pressure resistance should be tested as a sampling item when necessary. The withstand voltage test belongs to high voltage testing, and applying a voltage that is too high can cause hidden damage to the electric heater. Therefore, the applied test voltage is not necessarily better, and it needs to be in accordance with the standard (reference standard includes IEC60335-1) UL1030, JB/T4088-2012, JB/T2379-2016) shall be executed.

leakage current

Leakage current refers to the current flowing through the insulating medium when a component reaches a stable operating temperature state.

Leakage current is one of the important indicators to measure the insulation quality of electric heaters, and it is the main indicator to measure the safety performance of products.

The measurement method for leakage current: Connect the component to the voltage, adjust the test voltage to make the input power equal to 1.15 times the rated power, and measure the leakage current after the component reaches stable operating temperature.

The main factors affecting leakage current

Including the quality of insulation materials, production process control, sealing materials and sealing processes, and working temperature.

Under normal circumstances, leakage current is selected as a sampling item according to the standard (reference standard includes IEC60335-1) UL1030, JB/T4088-2012, JB/T2379-2016) are used to measure and verify the safety performance of the product.

Before leaving the factory, the leakage current of the electric heater shall not exceed 0.5mA, and specific industry standards shall also be followed for products.

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