Overvoltage protection circuit and power supply system

Abstract

Disclosed is an overvoltage protection circuit which interrupts power supply with a simple configuration by detecting an overvoltage applied to even a load of high electric power consumption. A first relay contact (14b) is connected between a polyphase power supply (12) and a compressor (16), and a first relay coil (14a) for controlling open / close of the first relay contact (14b) is provided in acontrol circuit (100) which consumes electric power less than the compressor (16). A second relay (140) is connected between the polyphase power supply (12) and a control circuit (100). When an overvoltage detection circuit (22) detects an overvoltage, a relay drive section (24) controls the energization of a second relay coil (140a) in the second relay (140) to cause interruption operation, thusinterrupting power supply from the polyphase power supply (12) to the control circuit (100). When power supply to the control circuit (100) is interrupted, power supply to the first relay coil (14a) is also interrupted and the first relay contact (14b) performs an interruption operation.

Description

technical field [0001] The invention relates to an overvoltage protection circuit and a power supply system loaded with the overvoltage protection circuit. Background technique [0002] An overvoltage protection circuit that detects an overvoltage of a power supply and cuts off power supply to a load is being put into practical use. For example, Patent Documents 1 and 2 below disclose that an overvoltage protection circuit in a circuit using a multiphase power supply is mounted in an air conditioner equipped with a compressor. [0003] Patent Document 1: (Japanese) Unexamined Patent Publication No. 4-161743 [0004] Patent Document 2: (Japanese) Unexamined Patent Publication No. H11-218346 [0005] However, in the techniques disclosed in the aforementioned Patent Documents 1 and 2, only the compressor can be protected, so there is a problem that other components (for example, a control board and a fan connected to the board) cannot be protected. Contents of the invention...

AI Technical Summary

Problems solved by technology

[0005] However, in the technologies disclosed in the above-mentioned patent documents 1 and 2, only the compressor can be protected, and therefore, other components (such as the control board and the fan, etc. connected to this base board)

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