Abstract: A cover for car lamps comprising a transparent base and a transparent element with variable coloring intensity capable of coloring and discoloring by electric conduction, disposed on at least a part of the base.

Abstract: A voltage/frequency converter is formed of a V/F converter circuit which converts an input potential into a frequency corresponding to the instantaneous value of the input potential, and a difference detection circuit which generates an output corresponding to the difference between the output frequency of the V/F converter circuit and a predetermined reference frequency. The V/F converter circuit is controlled according to the level of the output from the difference detection circuit, thereby reducing the deviation of the output frequency of said V/F converter circuit from the reference frequency.

Abstract: A digital protective relay system includes a read only memory (ROM) in which a program for executing calculations on a judgment formula for a predetermined protective relay function is stored. Switching of the judgement formula, from one form (e.g., over current protection) to another form (e.g., undervoltage protection), is facilitated by a setting unit and an operation mode switching unit which permit changing of judgement formula constants without changing the ROM program. The setting is used to input desired relay operation threshold values. The operation mode switching unit is used to specify the kind and sign of constants contained in a predetermined term in the judgment formula and also the kind of inequality in the formula.

Abstract: A relay device is disclosed which protects and controls an electric power line by detecting an electrical quantity carried by the electric power line. The relay device includes a rectifying circuit connected to the electric power line. The output of the rectifying circuit is supplied to a peak value holding circuit which stores the peak value of the output of the rectifying device during each predetermined period under control of a resetting pulse. The output of the peak value holding circuit is supplied to a detecting circuit having a predetermined threshold level.

Abstract: In a method and apparatus for supervising a digital protective relaying system, a first type of electrical quantities in an electric power system, each having a certain magnitude, are detected, digitized and operated on in a data processing unit to check whether there is a fault in any of first input circuits adapted to receive the first type of electrical quantities. To check whether there is a fault in a second input circuit which normally receives a second type of detected electrical quantity having a substantially zero magnitude, one of the first type of electrical quantities is inputted into the second input circuit, and the data processing unit performs an operation on the output of the second input circuit and the outputs of the first input circuits except for that first input circuit corresponding to the one of the first type of electrical quantities which is inputted to the second input circuit.