IEC 60068-2-78 Humidity Chamber - Combined Temperature/Humidity Testing

    Temperature and Humidity Test Chamber is used to test the performance of materials in various environments and test the heat resistance, cold resistance, dry resistance and humidity resistance of various materials. Suitable for testing the quality of products such as electronics, electrical appliances, mobile phones, communications, meters, vehicles, plastic products, metals,food, chemicals, building materials, medical care, aerospace, etc.

TEST CHAMBER APPLICATIONS
1. To simulate test environment with different temperature and humidity
2. Cyclic test includes climatic conditions: holding test, cooling-off test, heating-up test, moistening test and drying test…
3. Cable port with flexible silicone plug for cable routing to provide the condition of test unit under operation
4. Uncover test unit weakness in a short-term test with accelerated time effect

The selection of the ramp-up and ramp-down rates for a test chamber requires consideration of several factors to ensure the accuracy and reliability of the test results. The following are some of the key factors to consider when selecting the rate of temperature increase and decrease:

1. Test standards and specifications

Different test standards and specifications have specific requirements for warming and cooling rates. When selecting the rate, it is important to refer to the relevant international standards, national standards or industry specifications. For example:

GB/T 2423.1-2013: specifies the rate requirements for temperature change tests in environmental tests.

IEC 60068-2-14: specifies the rate of temperature change test.

2. Test purpose

Select the appropriate rate of temperature increase and decrease according to the purpose of the test:

Simulation of actual use environment: If the purpose of the test is to simulate the temperature change of the battery in the actual use environment, such as the use of electric vehicles in different climatic conditions, a rate similar to the rate of change of the actual environment should be selected.

Accelerated aging test: If the purpose of the test is to accelerate the aging process of the battery in order to assess its long-term stability and reliability, a higher rate of temperature rise and fall can be selected to shorten the test cycle.

3. Sample Characteristics

The characteristics and size of the sample will also affect the selection of the heating and cooling rate:

Thermal capacity: The greater the thermal capacity of the sample, the longer the time required for temperature changes. For large packs, longer ramp-up and ramp-down times may be required.

Thermal Conductivity: The better the thermal conductivity of the sample, the faster the temperature change. For materials with poor thermal conductivity, lower rates may be required to ensure temperature uniformity.

4. Equipment performance

The performance parameters of the tester also determine the range of ramp-up and ramp-down rates that can be selected:

Cooling and heating systems: High performance cooling and heating systems allow for faster rates of temperature change.

Temperature uniformity: The temperature uniformity of the equipment also affects the rate selection. To ensure that the sample is heated uniformly throughout the test, it may be necessary to adjust the rate based on the uniformity performance of the equipment.

5. Safety and Reliability

When selecting ramp-up and ramp-down rates, it is important to ensure the safety and reliability of the test process:

Avoid thermal stress: too rapid a temperature change may result in thermal stress within the sample, affecting the accuracy of the test results.

Equipment protection: too high a rate may place an excessive burden on the refrigeration and heating systems of the test chamber, affecting the service life of the equipment.

Specific selection method

Reference standards: first consult the relevant test standards to determine the recommended rate of temperature increase and decrease.

Sample characterization: analyze the heat capacity, thermal conductivity and other characteristics of the sample to determine the appropriate rate range.

Evaluation of equipment performance: According to the actual performance parameters of the test chamber, select the rate that the equipment can stably realize.

Pre-testing: conduct pre-testing before the official test to evaluate the test results under different rates and select the most suitable rate.

Example

Assuming that a certain lithium battery needs to be tested for temperature cycling, the test standard requires a temperature change rate of 5°C/min. The sample is a medium-sized battery pack with a large thermal capacity. The performance parameters of the test chamber are 10°C/min for maximum temperature increase and 5°C/min for maximum temperature decrease. in this case, a rate of 5°C/min can be selected to meet the standard requirements and ensure the safety and reliability of the test process.