Abstract: An apparatus is provided to determine deterioration of a photocoupler. The apparatus includes a detecting unit and a determining unit. The detecting unit receives an electric pulse signal outputted from the photocoupler. The amplitude of the outputted pulse signal depends on that of an electric AC voltage applied to the photocoupler. The detecting unit detects a duty ratio of the pulse signal. The determining unit determines whether or not the duty ratio is less than a threshold given for the determination. The determining unit also determines that the photocoupler has deteriorated in performance thereof more than a usable level if it is determined that the duty ratio is less than the threshold given for the determination.

Abstract: An apparatus is provided to determine deterioration of a photocoupler. The apparatus includes a detecting unit and a determining unit. The detecting unit receives an electric pulse signal outputted from the photocoupler. The amplitude of the outputted pulse signal depends on that of an electric AC voltage applied to the photocoupler. The detecting unit detects a duty ratio of the pulse signal. The determining unit determines whether or not the duty ratio is less than a threshold given for the determination. The determining unit also determines that the photocoupler has deteriorated in performance thereof more than a usable level if it is determined that the duty ratio is less than the threshold given for the determination.

Abstract: An electrical apparatus, which is immovable in a facility, comprises plural electric circuits. Each electric circuit has one or more resistance elements and is connected to each input terminal connected a power source. The electric circuits are arranged positionally closely with each other. In each electric circuit, a desired functional circuit is connected in series to the resistance element, and a protection circuit is connected in series to the resistance element and connected in parallel with the functional circuit. A discharge member is provided in each electric circuit and arranged between each input terminal and the functional circuit. The discharge member includes a discharge gap which allows the discharge member to face with the discharge member of an adjacently arranged electric circuit. The discharge gap discharge deliberately to the adjacently positioned discharge member when a voltage applied to a selected electric circuit exceeds a predetermined voltage value.

Abstract: An electrical apparatus, which is immovable in a facility, comprises plural electric circuits. Each electric circuit has one or more resistance elements and is connected to each input terminal connected a power source. The electric circuits are arranged positionally closely with each other. In each electric circuit, a desired functional circuit is connected in series to the resistance element, and a protection circuit is connected in series to the resistance element and connected in parallel with the functional circuit. A discharge member is provided in each electric circuit and arranged between each input terminal and the functional circuit. The discharge member includes a discharge gap which allows the discharge member to face with the discharge member of an adjacently arranged electric circuit. The discharge gap discharge deliberately to the adjacently positioned discharge member when a voltage applied to any of the electric circuits exceeds a predetermined voltage value.