To obtain a failure detector of a refrigerating showcase which can function as a circuit for determining positive and negative phases of a power supply when powering on at the installation of the showcase, can function as a circuit for detecting the operation of a protection circuit during normal operation after that, can separably use one circuit at the installation of the showcase and during the normal operation after the installation, can reduce the number of components of a detection circuit, and can reduce a space of a board circuit.
The refrigerating showcase comprises a refrigerator such as a compressor 1 with an overcurrent protection device connected thereto, and controls the operation of the showcase by using a showcase controller 3. Each of a power supply of a compressor protection operation detection circuit that takes out the operation state of the overcurrent protection device 4 of the three-phase power supply showcase compressor 1, and a power supply of the showcase controller 3, is constituted of two phases which are common to one phase from a three-phase power supply 2, and the negative phase connection of the three-phase power supply 2 is detected.
COPYRIGHT: (C)2008,JPO&INPIT
KOMIYA YASUYUKI
HOSAKA TAKASHI
OKAWA SHIGEAKI
NIPPON KENTETSU CO LTD
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Tadahiko Inaba
Kanako Murakami
Nakatsuru Kazutaka
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