| 摘要 |
PURPOSE:To detect easily and speedily a fault occurring to an ouptut device and a load circuit, and to improve the safety by flowing a current weak enough not to operate a load device to the load device when the logical level of an ouptut command is 0. CONSTITUTION:Even if the output command (s) falls in logical level to 0 to turn off a transistor (TR) 21, a weak current flows to a transformer 11 through a resistor 26 is long as voltages V1 and V2 are normal, and the voltage rectified by diodes 12 and 13, therefore, flows between the emitter and base of a TR14 for control; and the TR14 constitutes a common base amplifier, so the current amplification is almost 1 and the collector current is nearly equal to the emitter current. This current flows through the circuit in the order of a terminal 6, load device 5, resistor 15, TR14, diodes 12 and 13, and terminal 7 and monitored at test terminals 8 and 9 all the time. The current at this time is so set that the load device 5 does not operate. |
