A short circuit protection apparatus for a power conversion apparatus supplying power to a load via a plurality of switches connected to each other in parallel includes Ma current detectors each configured to detect a sum of currents flowing through two or more switches among the plurality of switches so as to output a detection signal indicative of the sum that is detected, wherein Ma is 1 less than M, which is the number of the plurality of switches, and a short circuit determiner configured to determine, based on detection signals obtained from the respective Ma current detectors, occurrence of short circuit failure in the plurality of switches to output a cutoff instruction signal for stopping on-off drive of the plurality of switches.

A short circuit protection apparatus for a power conversion apparatus supplying power to a load via a plurality of switches connected to each other in parallel includes Ma current detectors each configured to detect a sum of currents flowing through two or more switches among the plurality of switches so as to output a detection signal indicative of the sum that is detected, wherein Ma is 1 less than M, which is the number of the plurality of switches, and a short circuit determiner configured to determine, based on detection signals obtained from the respective Ma current detectors, occurrence of short circuit failure in the plurality of switches to output a cutoff instruction signal for stopping on-off drive of the plurality of switches.

In a power-supply control device, power supply to loads is controlled by driving circuits separately switching on or off FETs, respectively. In a state in which the connection destination of a fuse element is the FET, a microcomputer provides an instruction to switch the FET off. Then, the microcomputer determines whether or not a current is flowing through the FET. Upon determining that a current is flowing through the FET, the microcomputer switches the connection destination of the fuse element to the FETs, and provides an instruction to switch the FET on.

A safety circuit, in the form of a switch box, for coupling with a catheter, detects DC leakage or emission from an amplifier circuit of the catheter, and switches a switch to immediately terminates (cuts-off) power to the amplifier circuit. This immediate power termination instantaneously stops DC leakage, which if left unchecked or otherwise undetected, may reach the heart, and disrupt its electrical activity and cause other damage.

A safety circuit, in the form of a switch box, for coupling with a catheter, detects DC leakage or emission from an amplifier circuit of the catheter, and switches a switch to immediately terminates (cuts-off) power to the amplifier circuit. This immediate power termination instantaneously stops DC leakage, which if left unchecked or otherwise undetected, may reach the heart, and disrupt its electrical activity and cause other damage.

A protection circuit 60 is provided with: switches 61, 62 positioned on a power line PL of an electricity storage element 22 and a load 12; first protection elements 63, 64, 65 connected in parallel with the switches 61, 62 and absorbing surge caused when the switches 61, 62 open and cut off discharge current; and a second protection element 66 connected in parallel with the load and flowing, back to the load, the surge caused when the switches 61, 62 open and cut off the discharge current.

A metering and control subsystem for a photovoltaic solar system is configured for metering the photovoltaic solar system using current measurement devices and individually controlling relays to selectively energize photovoltaic branch circuits. In some examples, the metering and control subsystem includes photovoltaic branch connectors, a relay matrix, current measurement devices, and a metering and relay control circuit. The metering and control circuit is configured for metering the photovoltaic solar system using current measurement data from the current measurement devices and individually controlling the relays to selectively energize each photovoltaic branch circuit.

A series Z-source circuit breaker including a semiconductor switch that breaks source power being provided to a load in response to overcurrent. An electromechanical switch is electrically coupled in parallel with the semiconductor switch, a first capacitor is electrically coupled to an output side of the semiconductor switch, a second capacitor is electrically coupled in parallel with the semiconductor switch, and a delay circuit is electrically coupled in series with the first capacitor. The semiconductor switch is in an open position and the electromechanical switch is in a closed position when overcurrent is not present. Upon detection of overcurrent the semiconductor switch is closed, the electromechanical switch is opened and the delay circuit is controlled to delay when reverse bias current is provided from the first capacitor to the semiconductor switch to prevent source power from being provided to the load to give the electromechanical switch time to open.

A series Z-source circuit breaker including a semiconductor switch that breaks source power being provided to a load in response to overcurrent. An electromechanical switch is electrically coupled in parallel with the semiconductor switch, a first capacitor is electrically coupled to an output side of the semiconductor switch, a second capacitor is electrically coupled in parallel with the semiconductor switch, and a delay circuit is electrically coupled in series with the first capacitor. The semiconductor switch is in an open position and the electromechanical switch is in a closed position when overcurrent is not present. Upon detection of overcurrent the semiconductor switch is closed, the electromechanical switch is opened and the delay circuit is controlled to delay when reverse bias current is provided from the first capacitor to the semiconductor switch to prevent source power from being provided to the load to give the electromechanical switch time to open.

In order both to accommodate instantaneous current as well as overcurrent protection in accordance with the load, an overcurrent protection circuit has: a threshold value generation unit that, in accordance with a threshold value control signal, switches between setting an overcurrent detection threshold value to a first set value (∝ Iref) and a second set value (∝ Iset) lower than the first set value; an overcurrent detection unit that compares a sense signal in accordance with the current being monitored and the overcurrent detection value and generates an overcurrent protection signal; a reference value generation unit that generates a reference value (∝ Iset) in accordance with the seconds set value; a comparison unit that compares the sense signal and the reference value, and generates a comparison signal; and a threshold value control unit that monitors the comparison signal, and generates a threshold value control signal.