Start with the cooling method
Thyristor heatsink selection starts with the cooling method and mounting conditions. The Fuzheng catalogue identifies SF as air-cooling heatsinks and SS as water-cooling heatsinks; SF12 and SF17 belong to the SF series. A series designation does not establish cooling capacity under a particular operating condition.
Fuzheng Electronic Product Catalogue, edition 3, printed page 29 (PDF page 34)
Fuzheng Electronic Product Catalogue, edition 3, printed page 30 (PDF page 35)
Check SF12 and SF17 outline dimensions
The manufacturer-confirmed dimensional drawings give L × D × H as 200 × 110 × 125 mm for SF12 and 300 × 200 × 193 mm for SF17. Check cabinet space, then verify mounting holes, busbars and device contact surfaces against the corresponding drawing. Available space alone does not establish interchangeability.
SF12 / XSF12 · Dimensional drawing
SF17 / XSF17 · Dimensional drawing
The new drawings list geometry and individual thermal-resistance values, but do not specify the airflow or test conditions for those values. They do not establish an allowable heat-dissipation rating or universal pairing with a particular thyristor. A larger SF17 outline alone does not quantify additional current or power capacity.
SF12 / XSF12 · Dimensional drawing
SF17 / XSF17 · Dimensional drawing
Dimensions do not replace thermal design
Thermal design must consider device losses, the permitted junction temperature and actual cooling conditions together. Rth(j-c), Rth(c-hs) and Rth(hs-a) describe junction-to-case, case-to-heatsink and heatsink-to-ambient thermal resistance. Use data for the actual device and heatsink under stated test conditions; do not mix reference points or treat another manufacturer's figures as ratings for these models.
Operating conditions for a quotation
- Full device model, package and the source for its permitted junction temperature.
- Load-current waveform, duty cycle and the basis for loss calculations, not just nominal current.
- Maximum ambient temperature, cabinet temperature rise, mounting orientation and available space.
- Air path and fan operating conditions; for water cooling, also specify coolant, flow and temperature conditions.
- Contact surfaces, thermal interface material, insulation requirements and the device manufacturer's clamping or tightening requirements.
Mounting drawings and dimension notation
Check linear dimensions in millimetres. The new drawings mark SF12 mounting threads as 2-M6×20 and SF17 as 4-M8×20. M6 and M8 are thread designations, not tightening torques. Verify hole positions and other mounting dimensions against the corresponding new drawing; do not infer clamping force or tightening torque from thread designations.
SF12 / XSF12 · Dimensional drawing
SF17 / XSF17 · Dimensional drawing
Connect the selection documents to your enquiry
The related resources link to SF12, SF17 and the original catalogue. For a quotation, identify the candidate model and attach the device datasheet, mounting drawing and operating conditions listed above. If thermal-performance evidence is missing, establish the required data and compatibility conditions before finalising the selection.