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Russian Avalanche Thyristor TL4-250 series

The TL4-250 series avalanche thyristor is a low-frequency, silicon, diffusion type with a p-n-p-n structure, featuring flexible leads. It is designed for operation in power circuits of both DC and AC with a frequency up to 500 Hz and a current not exceeding 250 A.

The avalanche thyristor TL4-250 series is utilized in various power electrical installations, including rectifiers, inverters, regulators, converters, and circuits of both DC and AC equipment for industrial applications. It is housed in a metal-ceramic stud-type casing with flexible power and control leads, offering enhanced resistance to overvoltages.

The anode is a copper base of the casing, while the cathode is a flexible main lead. The type designation and polarity markings are indicated on the thyristor’s body. Cooling can be either natural air or forced air, with the recommended cooler type being OA-016.

The TL4-250 series avalanche thyristor is manufactured in climatic versions “UHL” in placement category “2” and “T” in placement category “3” according to GOST 15150-69. It can operate in ambient temperatures ranging from -50 to +60 °C.

The thyristor can withstand sinusoidal vibration in the frequency range of 1-100 Hz with an acceleration of 49 m/s² and multiple shocks with an acceleration of 117.6 m/s².


  • Overall length of the thyristor: 283 mm
  • Stud length: 20 mm
  • Thread: M30x1.5

The weight of the thyristor is not more than 700 g. It falls under the quality category “OTK” and adheres to technical specifications TU 16-529.766-77.

Thyristor Circuit Diagram

LJT Л 425010 

  • LJ-MD 
  • Thyristor
  • Л (L) Avalanche
  • 4 Series 
  • 250  Maximum permissible on-state current in amperes
  • 10 Class designation based on repetitive reverse voltage in hundreds of volts

For Symbols explanation CLICK HERE.

Maximum permissible values of parameters at Tp=25°CParameter values at Tp=25°C
Part NumberIT(AV)UDRM/URRMIDRM/IRRMITSMPRSMrT(duD/dt)crit(diT/dt)critUTMUT(TO)i2tIGTUGTtqtgtRthjc
Tj = -60 ~ +125°C
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Looking to revolutionize your power control solutions? Look no further. At LJ-MD, we specialize in delivering cutting-edge diode and thyristor technologies that meet the highest industry standards. With a strong focus on innovation, reliability, and performance, our products are designed to excel in a wide range of power applications.


From high surge current capability to precise power control, our diodes and thyristors offer exceptional features that cater to your specific needs. Whether you require efficient rectification, fast switching, or precise phase control, our products deliver reliable and precise results.


At LJ-MD, we understand that every project is unique. That’s why we provide personalized support and guidance to ensure you find the perfect solution for your requirements. Our team of experts is always ready to assist you in selecting the right product and providing technical assistance.


Don’t miss out on the opportunity to optimize your power control systems. Contact us today to discuss your project requirements, and let us help you find the ideal diode or thyristor solution to drive your success.

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