Published:2011/8/4 20:39:00 Author:Rebekka | Keyword: Electrical equipment overload , open-phase protection device | From:SeekIC
The device is composed of +12 V, +5 V DC power supply, AC transformer, voltage comparator, block timer, relay control circuit and phase loss protection circuits and other components. LH makes three-phase AC transformer current flowing couple in proportion, and they pass D1C1, D2C2, D3C3 rectifier filters and are added to the voltage comparator (IC1, DW1, DW5, R7) and phase-failure protection circuit (IC4, IC5, IC6). The phase loss protection circuit is composed of IC4 (CD4070), IC5 (7402), IC6 (CD4013). It is used for detecting and determine whether the three-phase current, if a phase-off phase, the IC3 will be set, the relay J Pick-up, the device will be cut off and the phase protection works.
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