| 摘要 |
PURPOSE:To realize a highly reliable protector by interrupting a load on condition that three requirements of voltage, apparent power variation of load and apparent power variation rate of load are satisfied for a specific time. CONSTITUTION:A first block 1 judges that the voltage is lower than a set value K1 while a second block 2 detects that the apparent load power variation is larger then a set value K2 and a third block 3 detects that the time variation rate of the apparent load power is higher than a set value K3. When these three requirements are satisfied, output from on AND gate 4 goes to 1 and when such condition continues longer than the set time T1 of a timer element 5, a load interruption command is provided. |
