The STR-1 transformer speed controllers are based on the principle of voltage control with auto-transformers. They are applicable to voltage-controllable motors (230 V, 50/60 Hz) to control in steps the rotational speed (of fans, pumps, etc.).
When choosing a controller it is important to know the maximum current intensity consumption on the taps. The indicated maximum current can be taken from each tap.
| Imax (A) | Fuse (A) | |
| STR-1-10L10 | 1,0 | (5×20 mm) 1,25 |
| STR-1-08L22 | 0,8 | (5×20 mm) 1,5 |
| STR-1-15L22 | 1,5 | 2,5 |
| STR-1-22L22 | 2,2 | 3,15 |
| STR-1-35L22 | 3,5 | 5,0 |
| STR-1-50L22 | 5,0 | 8,0 |
| STR-1-75L22 | 7,5 | 12,5 |
| STR-1100L22 | 10,0 | (6×32 mm) 16,0 |
| STR-1130L22 | 13,0 | 20,0 |
| STR-1160L20 | 16,0 | 25,0 |
| STR-1200L20 | 20,0 | 30,0 |
