A protection and monitoring system, device, and method for an electric power system, including a capacitor bank having multiple strings in each phase, voltage and current measuring devices, and relays to protect this capacitor bank. Each string can have multiple capacitor units and each unit can consist of multiple capacitor elements. The method may include: determining steady state operating condition using the obtained current and voltages, calculating and storing present time impedance value of each string into memory, calculating the string per unit impedance incremental quantity, detecting capacitor element failure based at least in part on this incremental quantity and calculating number of failed capacitor elements for each event, accumulating the number of failed capacitor elements, and performing a protection action when healthy capacitor elements are subject to an overvoltage limit. The method may be inherently immune or otherwise insensitive to capacitor variations due to aging, temperature change, instrument transformers errors, inaccuracy in data acquisition, and inherent manufacturing unbalance.

An example method may include generating an alternating current (AC) output at a power source within a borehole in a subterranean formation. An electrical component may receive a direct current (DC) output from a converter circuit coupled to the power source and the electrical component. One or more measurements corresponding to the power source, the converter circuit, the electrical component, or a protection circuit coupled to the converter circuit may be received. Blocking devices within the protection circuit may be selectively caused to block current flow in the converter circuit based, at least in part, on the one or more received measurements.

One or more embodiments relate to a control circuit for an input filter circuit in a switch mode power supply comprising a power switch and a switch controller to control the power switch to provide a regulated output voltage and current to a load. The control circuit, also referred to as a filter control circuit, can be used to detect a high voltage surge at its input and disconnect a capacitor in the input filter circuit from an input return, thereby protecting the input filter capacitor and the SMPS from damage. According to certain aspects, the control circuit can be integrated with the switch controller. Additionally, the control circuit can provide power to the switch controller at start-up.

One or more embodiments relate to a control circuit for an input filter circuit in a switch mode power supply comprising a power switch and a switch controller to control the power switch to provide a regulated output voltage and current to a load. The control circuit, also referred to as a filter control circuit, can be used to detect a high voltage surge at its input and disconnect a capacitor in the input filter circuit from an input return, thereby protecting the input filter capacitor and the SMPS from damage. According to certain aspects, the control circuit can be integrated with the switch controller. Additionally, the control circuit can provide power to the switch controller at start-up.

A safety switching device for the fail-safe disconnection of an external consumer has an internal consumer and switching elements for connecting in parallel the internal consumer with the external consumer. Read-back taps are arranged between the switching elements, a first and second pole of the external consumer, and the internal consumer. A signal processing unit includes a testing device and a memory, in which a first error pattern set is stored. The testing device is coupled to the read-back taps and executes a switching test having a minimum of three temporally-separated test intervals. In each test interval, the testing device receives a read-back signal from each read-back tap in order to generate a first test pattern. To identify a fault, the testing device matches the first test pattern with the first error pattern set.

A safety switching device for the fail-safe disconnection of an external consumer has an internal consumer and switching elements for connecting in parallel the internal consumer with the external consumer. Read-back taps are arranged between the switching elements, a first and second pole of the external consumer, and the internal consumer. A signal processing unit includes a testing device and a memory, in which a first error pattern set is stored. The testing device is coupled to the read-back taps and executes a switching test having a minimum of three temporally-separated test intervals. In each test interval, the testing device receives a read-back signal from each read-back tap in order to generate a first test pattern. To identify a fault, the testing device matches the first test pattern with the first error pattern set.

An AC/DC converter includes: an AC circuit breaker, configured as a hybrid circuit or semiconductor circuit breaker; a rectifier; a smoothing capacitor; a semiconductor switch connected in series with the smoothing capacitor; and a first isolation relay for galvanic isolation. One input of the AC circuit breaker forms an AC input of the converter. One output of the AC circuit breaker is connected with an input of the rectifier. The smoothing capacitor, and the first semiconductor switch, connect a first output of the rectifier with its second output. The first output of the rectifier is connected, with one input of the first isolation relay. The one output of the first isolation relay forms a first DC output of the AC/DC converter. The AC circuit breaker, the first semiconductor switch, and the first isolation relay are interconnected.

An AC/DC converter includes: an AC circuit breaker, configured as a hybrid circuit or semiconductor circuit breaker; a rectifier; a smoothing capacitor; a semiconductor switch connected in series with the smoothing capacitor; and a first isolation relay for galvanic isolation. One input of the AC circuit breaker forms an AC input of the converter. One output of the AC circuit breaker is connected with an input of the rectifier. The smoothing capacitor, and the first semiconductor switch, connect a first output of the rectifier with its second output. The first output of the rectifier is connected, with one input of the first isolation relay. The one output of the first isolation relay forms a first DC output of the AC/DC converter. The AC circuit breaker, the first semiconductor switch, and the first isolation relay are interconnected.

A circuit converts an AC or DC electrical input applied between first and second input leads into a DC output applied to a load via first and second output leads. Four thyristors have their anodes respectively connected to one of the first and second input leads or one of the first and second output leads. Cathodes of two thyristors are connected to the first and second output leads while cathodes of two other thyristors are connected to the first and second input leads. Gates of each thyristor are connected to respective unidirectional switches that open and close at the same time. When closed, the unidirectional switches polarize the gates. Thyristors having a positive voltage on their anodes apply this voltage to the first output lead to power the load. Thyristors having a negative voltage on their cathodes transmit return current from the load to the first or second input lead.

In the field of voltage source converters for high voltage direct current (HVDC) power transmission there is provided a protection arrangement for a switching device. The protection arrangement comprises a thyristor that has main current-carrying terminals which in use are connected in reverse parallel with a switching device to be protected, whereby during normal operation of the switching device a reverse voltage is applied to the thyristor. The protection arrangement also includes a trigger circuit that is operatively connected with a gate control terminal of the thyristor. The trigger circuit is configured to apply a voltage to the gate control terminal of the thyristor when the reverse voltage applied to the thyristor reaches a safety threshold voltage whereby the thyristor fails and presents an irreversible short-circuit across the main current-carrying terminals of the switching device.