| 摘要 |
The invention relates to an auxiliary teaching device used for studying the multitude of possibilities for the conversion of the clock hour figure of a three-phase transformer, using the conversion diagram. According to the invention, the device consists of a support plate (1) provided in its central part with a circular recess in which there is a circular plate (2) made of ferromagnetic material and being in contact with a friction roll (4) actuated from outside by means of a rosette-like button (4'), where the above mentioned recess is closed by means of a support plate (5), provided in the centre with a circular cut-out wherein a disk (6) integral with a scale (6') rotates, the disk (6) being fixed to the ferromagnetic plate (2) by means of some magnets ( 7 and 7') embedded in the disk material, in diametrally opposed positions and where the disk (6) can be separated from the ferromagnetic plate (2) by means of a key button provided with two distinct springs: a spring (10) for returning the button to the stand-by position and another spring (11) for separating the disk (6) from the ferromagnetic plate (2) by pushing. |
