| 摘要 |
<p>The current feed to the three-phase motor driven in a primary direction is interrupted, and after the elapse of a period set by a time delay relay, is reconnected after changing of at least two phase connections to it. Thus, the motor and the fan are driven in the opposite direction, and because of the fan characteristics its effect is altered but its air flow direction remains unvaried. The connecting medium between the three-phase motor and the A.C. three-phase mains comprises partly a switch for interrupting and connecting current to the motor and for changing at least two phases, and partly a time delay relay connected to the switch. This relay, after a current feed interruption, delays connection of current to the motor after changing two phases. (Provisional Basic advised week 84/06).</p> |
