NGI High-Performance Thermal Fuse Testing Solutions for Global Leaders

What Is a Thermal Cutoff (TCO)?

A thermal cutoff, also known as a thermal fuse, is a temperature-sensing safety device. Its operating principle is that when an electrical device experiences an overheating fault and the circuit temperature rises to the preset protection value, the thermal cutoff automatically melts and opens the circuit, thereby providing over-temperature protection. Based on the materials used in the temperature-sensing element, thermal cutoffs can be categorized into alloy-type TCOs, organic-type TCOs, and plastic–metal-type TCOs.

With the rapid development of emerging industries such as new energy vehicles, smart grids, and the Internet of Things, the application of thermal cutoffs will continue to expand. According to market reports, the global thermal cutoff market size was RMB 1.578 billion in 2019, with a 2019–2025 CAGR of approximately 6.4%, and is expected to reach RMB 2.286 billion by 2025.

Next, we will share with you the application of NGI high performance source loads to TOP thermal fuse customers worldwide.

Customer Requirements

Customer A is a global top-tier manufacturer of circuit protection components such as thermal cutoffs and thermostats. Their products are widely used by leading brands including Haier, BMW, and Huawei, providing reliable, safe, and stable over-temperature protection solutions to tens of thousands of customers.

Based on preliminary technical discussions, the customer requires Inrush Current testing for their newly developed DC thermal cutoffs, with reference to IEC 60691:2023 (GB/T 9816.1-2023).

According to the standard, inrush current testing must meet the following core requirements:

DUT

Thermal cutoffs with:

Rated voltage ≤ 690 V (AC/DC)

Rated current ≤ 63 A

Test Conditions

Current pulse: 3 ms width, amplitude of 15 × rated current (15 Ir), interval of 10s

Cycle count: 100 continuous cycles

Acceptance criteria: The thermal cutoff shall not operate and no damage shall occur after the test.

Please refer to the following image for details:

NGI Testing Solution

Power Supply + Electronic Load Collaborative Test Architecture

After multiple rounds of in-depth technical communication and on-site sample testing demonstrations, the customer ultimately selected NGI’s N36200 series wide-range programmable DC power supply combined with the N69200 series high-performance, high-power programmable DC electronic load as a combined testing solution, fully meeting the standard requirements for instantaneous overload current testing of thermal cutoffs.

The relevant test waveforms are as follows:

20A thermal fuse test waveform diagram

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