| 摘要 |
PROBLEM TO BE SOLVED: To prevent burning of a brake resistor and damage of a switching element by outputting a failure signal if a detection current is not generated upon elapsing a predetermined time after a brake signal is outputted from a setting comparing means. SOLUTION: The protector for brake system comprises a setting comparator 2 delivering a brake signal Br when a DC voltage Vdc exceeds a brake set level Vb and the brake signal Br is normally delivered to a signal interrupter 7 and a failure detector 6 when the DC voltage Vdc exceeds the brake set level Vb. If a current detector 4 is damaged when a current flows through a brake resistor 1 and a detection current ir can not be outputted, a failure signal is outputted with a predetermined time lag T to the signal interrupter 7 which interrupts the brake signal forcibly. A conductor 9 also interrupts an AC power supply 8 and an inverter 10 to stop the inverter 10. According to the arrangement, burning of the brake resistor and damage of the switching element can be prevented. |
