Line pin porcelain insulators are designed for an insulation and mounting of the wires of overhead transmission lines of DC current and AC current with a voltage up to 1000 V and a frequency up to 100 Hz, as well as communication lines. They meet the requirements of DSTU 3546-97 (GOST 30531-97). The material of the insulation part is a ceramic electrotechnical material of a subgroup 110 GOST 20419-83.
| Insulator name | Designation of the drawing | DSTU (GOST) | Voltage class, kV | N, mm | D outer, mm | Weight, kg | Rough drawing | |
| nom. | prev. deviation, ± 7% | |||||||
| ТФ-20 О1 | НИЮД.757516.010 | DSTU 3546-97 (GOST 30531-97) | до 1 кВ | 100 | 70 | 0,49 | 0,0343 |  |
The following letters and figures in the conventional value of insulator type denote:
T – telephone;
F – porcelain;
20 – diameter of a pin or hook on which the insulator is fixed, mm;
O – climatic version;
1 – placement category.