An outdoor unit includes: first, second, third, and fourth connection terminals all of which are connected to an indoor unit; a power converter; and a switch unit provided between the first connection terminal and the power converter. The indoor unit includes: a first indoor unit terminal connected to the first connection terminal; a second indoor unit terminal connected to the second connection terminal; a third indoor unit terminal connected to the third connection terminal; a fourth indoor unit terminal connected to the fourth connection terminal; and a switch provided between the first indoor unit terminal and the fourth indoor unit terminal. The switch unit includes: a first switch that is closed when receiving power supply from the second and fourth connection terminals; and a second switch connected in parallel with the first switch. AC power is applied to the first and second connection terminals. The indoor unit closes the switch upon receiving a start signal, and the outdoor unit closes the second switch after supply of AC power to the power converter starts.

An outdoor unit includes: first, second, third, and fourth connection terminals all of which are connected to an indoor unit; a power converter; and a switch unit provided between the first connection terminal and the power converter. The indoor unit includes: a first indoor unit terminal connected to the first connection terminal; a second indoor unit terminal connected to the second connection terminal; a third indoor unit terminal connected to the third connection terminal; a fourth indoor unit terminal connected to the fourth connection terminal; and a switch provided between the first indoor unit terminal and the fourth indoor unit terminal. The switch unit includes: a first switch that is closed when receiving power supply from the second and fourth connection terminals; and a second switch connected in parallel with the first switch. AC power is applied to the first and second connection terminals. The indoor unit closes the switch upon receiving a start signal, and the outdoor unit closes the second switch after supply of AC power to the power converter starts.

A DC power supply device includes a housing including a wall portion, a first opening and a second opening, a circuit portion, a regulation wall portion, and a fan. The first and second openings are formed in the wall portion. The circuit portion includes first and second circuit elements those fixed within the housing. The regulation wall portion provide a first air passage in communication with the first opening, a second air passage in communication with the second opening, and a bent air passage allowing the first air passage and the second air passage to communicate with each other. The fan is configured to generate an air-flow flowing between the first air passage and the second air passage. The fan is positioned to face the first opening. The first circuit element is positioned in the first air passage. The second circuit element is positioned in the second air passage.

A DC power supply device includes a housing including a wall portion, a first opening and a second opening, a circuit portion, a regulation wall portion, and a fan. The first and second openings are formed in the wall portion. The circuit portion includes first and second circuit elements those fixed within the housing. The regulation wall portion provide a first air passage in communication with the first opening, a second air passage in communication with the second opening, and a bent air passage allowing the first air passage and the second air passage to communicate with each other. The fan is configured to generate an air-flow flowing between the first air passage and the second air passage. The fan is positioned to face the first opening. The first circuit element is positioned in the first air passage. The second circuit element is positioned in the second air passage.

A high-compatibility dimmer circuit is provided, which includes an impedance inspection avoidance module, a dimming module and an alternating-current input module. The impedance inspection avoidance module is connected to a load via an output end. The dimming module is connected to the impedance inspection avoidance module and includes a control unit. The alternating-current input module is connected to the dimming module, and converts an input alternating voltage into a pulsating direct voltage so as to power the load and the dimming module. When the load is driven, the control unit starts timing and switches the impedance inspection avoidance module after a predetermined time period. In this way, the dimming module can directly power the load and perform dimming for the load according to a dimming signal.

A high-compatibility dimmer circuit is provided, which includes an impedance inspection avoidance module, a dimming module and an alternating-current input module. The impedance inspection avoidance module is connected to a load via an output end. The dimming module is connected to the impedance inspection avoidance module and includes a control unit. The alternating-current input module is connected to the dimming module, and converts an input alternating voltage into a pulsating direct voltage so as to power the load and the dimming module. When the load is driven, the control unit starts timing and switches the impedance inspection avoidance module after a predetermined time period. In this way, the dimming module can directly power the load and perform dimming for the load according to a dimming signal.

The present disclosure provides a light-emitting diode lamp designed to replace an incandescent filament bulb for illumination purposes in a transportation vehicle and a light-emitting diode circuit associated therewith.

The present disclosure provides a light-emitting diode lamp designed to replace an incandescent filament bulb for illumination purposes in a transportation vehicle and a light-emitting diode circuit associated therewith.

In a power converter, an inductance L of a reactor and a capacitance C of a capacitor satisfy a condition of the expression (1) below. In the power converter, a current-limiting circuit between an AC power source and the capacitor is unnecessary. Herein, αm ([A.Math.s]) is a value of a ratio of a maximum rated current squared time product to a maximum rated output current of diodes of a rectifier circuit, Pmax is a maximum power consumption of the motor, Vac is a voltage value of a three-phase AC voltage, and a value of a constant a is 4.3 $\begin{array}{cc}a.Math.C.Math.\sqrt{\frac{C}{L}}.Math.\frac{{\mathrm{Vac}}^3}{P_{\max }}\le {\alpha }_m.& \left(1\right)\end{array}$

A power supply device may include a connector configured to electrically couple the power supply device to a conductor of the underground power lines; a voltage divider configured to receive an input voltage from the conductor, the voltage divider comprising a capacitor and divider voltage control electronics in series with the capacitor; and, a surge resistor in series with the capacitor and configured to provide impulse protection from surge events. The divider voltage control electronics may be configured to regulate an output voltage of the voltage divider to support variable loads on the voltage divider.