High Resistance 50Kohm Thermal Fuse Cement Resistors Heat Resistant
- It is suitable for protecting circuit boards.
- Flameproof construction in a ceramic case, resistant to humidity and insulation.
- In high resistance value, the winding cores will be replaced by power film cores.
- Excellent anti-surge characteristics and accurate fusibility.
The SQF series is a thermal fuse cement resistor designed for circuit protection applications. It uses a ceramic case and winding structure, combining resistor functionality with thermal fuse protection for circuit designs where resistive loading and thermal protection are required in the same component.
As a fusible wire wound resistor, the SQF series can be used in PCB protection positions. Rated current options include 3A, 5A, and 10A, while rated functioning temperatures include 132°C, 145°C, and 185°C, allowing engineers to select a specification according to the circuit's operating conditions.
The SQF series references IEC 60115-1 and JIS C 5201-1. Ordering information includes the type, nominal resistance, resistance tolerance, rated functioning temperature, rated current, and RoHS compliance.

| Parameter | SQF Series Specification |
|---|---|
| Product Type | Thermal Fuse Cement Resistor |
| Series | SQF3 / SQF5 / SQF7 / SQF10 / SQF10S |
| Construction | Ceramic case, wire wound construction |
| Rated Current | 3A / 5A / 10A |
| Rated Functioning Temperature | 132°C / 145°C / 185°C |
| Resistance Range | 0.1Ω~50kΩ; SQF10 specifications start from 0.8Ω |
| Resistance Tolerance | ±5% (J) |
| Temperature Coefficient | 300 ppm/°C; some specifications 600 ppm/°C |
| Insulation Resistance | 1000MΩ, DC 500V |
| Dielectric Withstanding Voltage | AC 1000V, 1 minute |
| Terminal Strength | 4.5kg |
| Solderability | Minimum 95% coverage |
| Resistance to Soldering Heat | 265±5°C, 10±1 seconds |
The specifications above are based on the SQF series product document. Because some dimensional and rating data in the original PDF are presented in graphic-table format and are not fully recoverable from the text layer, unavailable dimensional values have not been inferred.

SQF thermal fuse cement resistors can be used in protection positions on industrial control boards. When a circuit requires both resistance and thermal fuse protection, engineers can select the appropriate specification according to the 3A, 5A, or 10A rated current and the 132°C, 145°C, or 185°C rated functioning temperature.
In industrial power-related circuits, a fusible resistor can provide resistance while incorporating a thermal fuse protection function under the specified operating conditions. The AC 1000V dielectric withstand test and 1000MΩ insulation resistance specification provide defined electrical parameters for component selection in power circuits.
The product document explicitly states that the SQF series is suitable for protecting circuit boards. It can therefore be considered for PCB designs requiring circuit protection. The ceramic case construction, rated functioning temperature, and rated current provide key parameters for engineering selection.
For industrial electronic equipment requiring a safety resistor or circuit protection resistor, the SQF series can be selected according to nominal resistance, rated current, and rated functioning temperature. Its wire wound construction and ceramic case provide defined structural characteristics for resistor installation in industrial electronic circuits.
The SQF series documentation specifically states “Excellent anti-surge characteristics” and specifies a short-time overload test at 16 times rated wattage for 5 minutes. Therefore, it can be evaluated as an anti-surge fusible resistor for circuits exposed to short-duration abnormal loads or surge conditions. Actual component selection should be based on the circuit's surge energy and operating conditions.
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