Abstract: A casting apparatus has a melting pot (4) in which pieces of metal (8) to be melted is placed. A RF induction heater coil (10) is disposed in association with the melting pot (4) to heat the metal pieces (8). An inverter (18) supplies the coil (10) with high-frequency power to melt the metal pieces (8) in the melting pot (4), and the resulting molten metal is poured into a die (6). A control unit (36), after all of the metal pieces (8) having various sizes and shapes are melted, causes the operation of the inverter (18) to continue for a first time period and, after that, to suspend the operation of the inverter (18) for a second time period so that the heating can be stopped. After that, the control unit (36) causes the inverter (18) to resume its operation to heat the melted metal (8) in the melting pot (4) until the molten metal (8) assumes a predetermined state and, a third predetermined time after that, operates a melting pot driver (9) to cause the molten metal (8) to be poured into the die (6).

Abstract: A casting apparatus has a melting pot (4) in which pieces of metal (8) to be melted is placed. A RF induction heater coil (10) is disposed in association with the melting pot (4) to heat the metal pieces (8). An inverter (18) supplies the coil (10) with high-frequency power to melt the metal pieces (8) in the melting pot (4), and the resulting molten metal is poured into a die (6). A control unit (36), after all of the metal pieces (8) having various sizes and shapes are melted, causes the operation of the inverter (18) to continue for a first time period and, after that, to suspend the operation of the inverter (18) for a second time period so that the heating can be stopped. After that, the control unit (36) causes the inverter (18) to resume its operation to heat the melted metal (8) in the melting pot (4) until the molten metal (8) assumes a predetermined state and, a third predetermined time after that, operates a melting pot driver (9) to cause the molten metal (8) to be poured into the die (6).

Abstract: A power supply apparatus has chassis (42, 44) mounted on opposing surfaces of a heat sink (40). Printed circuit boards (46, 48) are disposed outward of the chassis (42, 44) and detachably secured to the chassis (42, 44). Semiconductor modules (4, 16a, 16b, 32) are mounted on the respective surfaces of the heat sink (40) facing toward the printed circuit boards (46, 48) and extend through the chassis (42, 44). The semiconductor modules (4, 16a, 16b, 32) are electrically connected to the printed circuit boards (46, 48) to form a power supply circuit.

Abstract: A cooling apparatus for electrical equipment having heat-generating components, air-intake apertures and air-outlet apertures includes a fan, a forward-rotation power control circuit, a reverse-rotation power control circuit, an indicator, a long-term timer and a short-term timer. The forward-rotation power control circuit rotates the fan in a forward direction such that air flows in through the air-intake apertures, over the heat-generating components and away through the air-outlet apertures, in response to a forward-rotation command signal. The reverse-rotation power control circuit rotates the fan in the opposite direction. The long-term timer continuously applies the forward-rotation command signal to the forward-rotation power control circuit during a first predetermined period. The indicator indicates the expiration of the first predetermined period.

Abstract: A power supply apparatus for welders includes an input-side AC-to-DC converter for converting an input commercial AC voltage into a DC voltage, which is, in turn, converted to a high-frequency voltage in an inverter. The high-frequency voltage is transformed to a high-frequency voltage having a desired magnitude in a transformer. The transformed high-frequency voltage is then converted back to a DC voltage in an output-side high-frequency-to-DC converter. The DC voltage is developed between output terminals of the power supply apparatus. A current detector detects the current flowing through the output terminals and develops a detected-current representative signal. A voltage detector detects the voltage between the output terminals and develops a detected-voltage representative signal. A CPU has three control modes and controls, in a first mode, the inverter in such a manner that the current representative signal becomes equal to a reference-current representative signal.

Abstract: An input-side rectifier of a DC power supply apparatus receives and rectifies an AC voltage selected from first and second groups of AC voltages. The AC voltages in the second group are lower than those of the first group. A voltage boosting/lowering converter boosts or lowers the output voltage of the input-side rectifier to a voltage having a predetermined value. An inverter converts the output voltage of the voltage boosting/lowering converter to a high-frequency voltage. A voltage transformer transforms the high-frequency voltage from the inverter. An output-side rectifier rectifies the transformed high-frequency voltage from the transformer.

Abstract: A power supply apparatus includes a front panel, a rear panel and two left and right side panels which together form a housing. Opposed edges of a partition are connected to the front and rear panels to thereby divide the interior space of the housing into upper and lower chambers. The left and right side panels each have edges which are placed to abut against the corresponding edges of the other side panel.Components of a power supply circuit are appropriately distributed in the upper and lower chambers. Some of the components in the upper chambers are located beneath the upper abutting edges of said left and right side panels, and a cover is disposed to cover at least those components which are located beneath the upper abutting edges.

Abstract: DC power supply apparatus includes an input-side rectifier for converting an AC signal from an AC power supply into a DC signal. A DC-to-high-frequency converter converts the DC signal into a high frequency signal in response to a control signal from a control unit. An output-side rectifier converts the high frequency signal into a DC signal and applies it to a load. An input current detector detects an input current flowing through the input-side rectifier and generates a signal representative of the input current. A load current detector detects a load current flowing through the load and generates a signal representative of the load current.