| 摘要 |
In the device phase voltage (RPh/RN), transformed (2) and rectified (3), gives a 30 V DC output, which, filtered (4,7,8) and regulated (6), provides a 12 V power supply (Vcc). The transformer sec. voltage is applied (9) to paired photo-transistors (10), acting as a zero-phase detector which provides one line (11) to a NAND-gate (13). The other line (22) derives from an overvoltage detector, a subtractor (18) with associated Zener diodes (19,20). The gate output, inverted (39), drives a transistor switching unit (23,24), energising the circuit-breaker (27) operating coil (26), so interrupting the main circuit. It is also (29) applied to a NAND-gate (30) whose other input is the subtractor output, inverted (31). This gate initiates the delay unit (33) which (34,35) resets the circuit-breaker control circuit (23), provided the original overvoltage has disappeared. USE - Esp. for neutral voltage displacements.
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