| 摘要 |
<p>PURPOSE:To reduce the size of a brake unit by detecting a malfunction by the conditions of a current flowed to a brake resistor in a generative brake circuit and a power running time. CONSTITUTION:When a thyristor 13 for a generative brake is erroneously fired due to an external noise at a power running time, a current is flowed to a brake resistor 12. Since the resistor 12 is not affected by a cooling air at the power running time, the possibility of burnout occurs. Thus, the presence or absence of the current flowed to the resistor 12 is detected by a signal from a current detector 18, and an NAND circuit 20 discriminates whether the conditions of the power running current are satisfied or not. When the conditions of the power running current are satisfied, a load breaker 5 is opened to provide a protective sequence of interrupting the current of a main circuit.</p> |
