| 摘要 |
PURPOSE: An SSR(Solid State Relay) having an over-current relay is provided to protect effectively a load device such as a motor or a heater from over-current by installing an electric over-current relay at the SSR. CONSTITUTION: A current detection portion(10) has a plurality of CT sensors(CT1 to CT3) in order to detect over-current from a three phase load power source or a single phase load power source. A voltage conversion portion(20) converts an output voltage of the current detection portion(10). A comparison portion(40) compares an output voltage of the voltage conversion portion(20) with a reference voltage of a reference voltage generation portion(30). The first switching portion(50) is turned on according to an output of the comparison portion(40) through an OR gate. The second switching portion(60) is turned on by a photo relay(PRY). A display portion(70) displays a state of overload.
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