Performance Requirements for Cartridge Heaters

Cartridge heaters, as opposed to standard tubular heating elements, have several specific performance requirements, primarily reflected in the following aspects:

1. Heating Time Requirement: Cartridge heaters have strict requirements for heating-up time. Under test voltage, the time for the element to rise from ambient temperature to the test temperature should not exceed 15 minutes.

2. Rated Power Tolerance: Under conditions of sufficient heat dissipation, the deviation of the element's rated power should not exceed the following specified ranges:
   a. For elements with a rated power ≤ 100W: ±10%.
   b. For elements with a rated power > 100W: +5% to -10% or 10W, whichever is greater.

3. Leakage Current Requirements:
   a. Cold leakage current and leakage current after hydrostatic pressure and seal tests should not exceed 0.5 mA.
   b. Hot leakage current at operating temperature should not exceed the value calculated by the following formula, with a maximum limit of 5 mA.
   I = 1/6 * (t * T * 0.00001)
   Where: I — Hot leakage current (mA); t — Heating length (mm); T — Operating temperature (°C).
   c. When multiple elements are connected in series to a power source, leakage current testing should be performed on the entire group as a whole.

4. Insulation Resistance Requirements:
   a. For factory acceptance tests, the cold insulation resistance should be not less than 50 MΩ.
   b. After seal testing, or following extended storage or use, the insulation resistance should not be less than 1 MΩ.
   c. The hot insulation resistance at operating temperature should be not lower than the value calculated by the following formula, with a minimum value of not less than 1 MΩ.
   R = [(10 - 0.015T) / t] * 0.001
   Where: R — Hot insulation resistance (MΩ); t — Heating length (mm); T — Operating temperature (°C).

5. Dielectric Withstand Strength (Hi-Pot Test): The element should withstand the specified test voltage under defined test conditions for 1 minute without flashover or breakdown.

6. Cycling (On/Off) Endurance: The element should withstand 2000 cycles of switching on and off under specified test conditions without damage.

7. Overload Capacity: The element should withstand 30 cycles of overload testing under specified test conditions and input power without damage.

8. Thermal Endurance: The element should withstand 1000 cycles of thermal endurance testing under specified test conditions and voltage without damage.