A system includes a dry contact with a first pair of switchable electrodes, a wet contact with a second pair of switchable electrodes, an arc suppressor, and a controller circuit operatively coupled to the arc suppressor and the first and second pairs of switchable electrodes. The controller circuit is configured to detect a failure of the wet contact and determine a stick duration associated with the first pair of switchable electrodes. The stick duration is based on a duration between an instance when a coil of the dry contact is deactivated and an instance of separation of the first pair of switchable electrodes during deactivation of the coil. The controller circuit generates, in-situ and in real-time, health assessment for the first pair of switchable electrodes based on a comparison of the determined stick duration with an average stick duration associated with a window of observation.

Disclosed herein is an overcurrent protection circuit configured to, upon detection of an output current that flows through a switch element reaching a first overcurrent limit value, reduce an overcurrent limit value for the output current from the first overcurrent limit value to a second overcurrent limit value smaller than the first overcurrent limit value.

According to an aspect of this disclosure, an intrinsically safe circuit includes a voltage source, a Zener diode, a transistor, a switching element, one or more resistors, and a current limiting stage. According to this aspect, the intrinsically safe circuit may be configured such that an over-voltage threshold is determined by a voltage across the Zener diode, a base-emitter voltage of the transistor, and a voltage across the one or more resistors.

An apparatus includes a controller. The controller monitors a magnitude of first current supplied by an output voltage of a first power converter to power a dynamic load. The controller controls a second power converter to supply second current through the dynamic load based on the monitored magnitude of first current.

An apparatus includes a controller. The controller monitors a magnitude of first current supplied by an output voltage of a first power converter to power a dynamic load. The controller controls a second power converter to supply second current through the dynamic load based on the monitored magnitude of first current.

A direct current circuit breaker, including: n in number circuit breaker modules connected in series, one energy-absorbing and voltage-limiting module connected in parallel to the n in number circuit breaker modules, and a trigger module. The n in number circuit breaker modules each includes a mechanical switch and a commutation branch circuit which are connected in parallel; each commutation branch circuit includes a charging commutation module and a commutation capacitor which are connected in series; the charging commutation module is configured to charge up the commutation capacitor and produce reverse current to cut off the mechanical switch; the one energy-absorbing and voltage-limiting module is configured to absorb energy stored in inductive elements of power systems after a fault current is cut off, so as to limit voltage and protect the mechanical switch, and n is a positive integer greater than or equal to 1.

A direct current circuit breaker, including: n in number circuit breaker modules connected in series, one energy-absorbing and voltage-limiting module connected in parallel to the n in number circuit breaker modules, and a trigger module. The n in number circuit breaker modules each includes a mechanical switch and a commutation branch circuit which are connected in parallel; each commutation branch circuit includes a charging commutation module and a commutation capacitor which are connected in series; the charging commutation module is configured to charge up the commutation capacitor and produce reverse current to cut off the mechanical switch; the one energy-absorbing and voltage-limiting module is configured to absorb energy stored in inductive elements of power systems after a fault current is cut off, so as to limit voltage and protect the mechanical switch, and n is a positive integer greater than or equal to 1.

Provided is a current limiting circuit (30) configured to: before release of a touch between a second contact (20b) provided at a position where a terminal (11a) on a power receiving side in which a current flows at supply of DC power in an electrode that supplies the DC power touches before touching a first contact (20a) provided for the electrode at supply of the DC power and the terminal (11a), decrease the current flowing into the terminal (11a) through the second contact (20b); and avoid flowing a current in a case where the terminal (11a) is touching the first contact (20a), and decrease the current flowing into the terminal (11a) through the second contact (20b) only in a case where the terminal (11a) is touching the second contact (20b).

Provided is a current limiting circuit (30) configured to: before release of a touch between a second contact (20b) provided at a position where a terminal (11a) on a power receiving side in which a current flows at supply of DC power in an electrode that supplies the DC power touches before touching a first contact (20a) provided for the electrode at supply of the DC power and the terminal (11a), decrease the current flowing into the terminal (11a) through the second contact (20b); and avoid flowing a current in a case where the terminal (11a) is touching the first contact (20a), and decrease the current flowing into the terminal (11a) through the second contact (20b) only in a case where the terminal (11a) is touching the second contact (20b).

An object is to provide a DC power supply connector that can suppress occurrence of an arc discharge at DC power off with a small-scale configuration without reducing power efficiency during DC power supply and can reduce heat generation.

The connector includes, on at least any of a positive-electrode-side electrode side and a negative-electrode-side electrode side, a movable contact piece (20c) that touches a first contact (25) in a state where a terminal (11) on a power receiving side has been inserted and to touch a second contact (24) in a state where the terminal has not been inserted, and a current limiting circuit (30) including a switching element (T1). The current limiting circuit (30) does not flow a current to the switching element (T1) in the case where the movable contact piece (20c) is touching the first contact (25), and flows a current to the terminal (11) through the movable contact piece (20c) until the movable contact piece (20c) is linked to the second contact (24) after separation from the first contact (25), and gradually decreases the flowing current.