Abstract: A neon transformer includes secondary windings 16 and 17, and a junction 20 therebetween is connected through a voltage detection circuit 41 to a ground terminal 18 of the transformer. A resistive element 54 is connected in shunt with the voltage detection circuit 41. The voltage detection circuit 41 may comprise a series circuit of a Zener diode 52 and a light emitting element 53L of a photocoupler, for example. When a ground fault occurs on the secondary side of the transformer, the location of the ground fault assumes a reference potential, whereby the potential of the junction 20 rises to cause a current flow through the Zener diode 52 and the light emitting element 53L, which renders a light receiving element 53P conductive to pass an energizing current through a relay drive coil 34, thus throwing a relay contact switch 13 from NC to NO, thus interrupting the supply of the a.c. power.

Abstract: An abnormality detection circuit 22 delivers a detected abnormality relating to a transformer 11. An interrupter circuit 23 turns a switch 16 off to interrupt the supply of the power to the transformer 11. When the supply of the power is interrupted, the switch 16 is connected to a restart circuit 31, whereupon the circuit 31 is activated to allow a charging current to flow to a capacitor, which is connected in series in a drive current path of a drive circuit 32 with a time delay on the order of 0.5 to 1.0 second which is determined by a delay circuit thereof. The charging current drives a restoring circuit 33, which controls the interrupter circuit 23 so that the switch 16 is turned on.

Abstract: Induced voltages of two tertiary coils magnetically coupled with two secondary coils, respectively, are detected separately by two voltage detector circuits, and the detected voltages V1 and V2 are compared by two comparators with a reference voltage VS. When wiring connected to either one of the two secondary coils or a neon tube is grounded, the induced voltage of the corresponding tertiary coil decreases, then the output from the corresponding comparator is reduced down to zero volt, then a light emitting element emits light, and a phototriac is turned ON to actuate a relay to turn OFF its contact switch, shutting off the supply of AC power.

Abstract: For use with a transformer unit comprising a main housing accommodating a transformer, a coil case is provided which encloses a high-voltage coil and the magnetic core section around which said coil is mounted. Only the interior space of the coil case is filled with insulating compound.

Abstract: A dividing ratio is represented by a ratio (M/N) of two integers (M) and (N), and six data (N), (-N), (M), (M+N), (M-N) and (0) are generated, then one of the six data is selected on the basis of a condition that is predetermined by an input signal to be divided and a comparison result of the data (N), (-N) and data which is derived by addition or subtraction between the selected data from the six data and the previous calculation result of the addition or subtraction; and output or interception of an output signal is controlled on the basis the comparison result, and thereby the input signal is divided by the dividing ratio (M/N).