There is a need to monitor and control the state of relays and circuit breakers within power distribution systems. The monitoring of a relay state, i.e. open or closed, is often performed by applying a monitoring signal to sensing contacts added to the relay. Manufactures of such systems have chosen many different voltages for their own monitoring systems making it difficult to interconnect dissimilar monitoring systems. A signal conditioning circuit is provided that can cope with a large input voltage range and can be configured to allow may items of equipment (which may be new item or legacy items) to be connected to a controller.

A circuit for controlling an input current, the circuit includes a first input port configured to receive the input current. A current detector detects an input current value of the input current and generates a control signal indicative of the input current value. A first output port outputs an output current to a load. A second output port receives the output current from the load. A control circuit provides a low-impedance path in parallel with the load in response to the control signal indicating the input current value is below a threshold value.

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 operatively, 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 controller circuit generates a 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.

A method for cleaning electrical contacts of an electrical switching device includes displacing a first electrical contact element and a second electrical contact element of an electrical contact relative to each other so that the first electrical contact element and the second electrical contact element are in a closed position; and when the first and second electrical contact elements are in the closed position applying a waveform on the electrical contact so that the first contact element and the second contact element are excited to undergo a mechanical vibration relative to each other.

A transmission device includes a pair of terminals connected to an electrical coupler via a pair of signal lines, a transmission unit connected to the pair of terminals via a pair of capacitor, and a DC power supply, a switch, and inductances, each connected in series between the pair of terminals without interposition of the pair of capacitors. A transmission device includes a pair of terminals connected to an electrical coupler via a pair of signal lines, a reception unit connected to the pair of terminals via a pair of capacitors, and a load resistor and inductances each connected in series between the pair of terminals without interposition of the pair of capacitors.

A method for removing oxidation of a contact of a trigger switch of a battery pack powered tool. The method includes receiving power from one or more battery packs coupled to the battery pack powered tool, determining, with a controller, that a trigger of the battery pack powered tool has been actuated, and providing, with a wetting circuit, power from the one or more battery packs to the contact to remove an oxidation surface film on the contact.

A switch monitoring device includes a constant current source which supplies a current to an input line or extracts a current from the input line, a switch which connects the input line to a supply voltage or to a ground voltage, a comparator which compares a voltage on the input line with a reference voltage, a logic which receives an output voltage of the comparator, a base current source which generates a base current, and a bias current circuit which generates a bias current by adjusting the base current as a base in accordance with a current control signal from the logic and the output voltage of the comparator. The constant current source generates a current by adjusting the bias current as a base.

A system and method according to various embodiments can include a universal contact input status detection circuit. A voltage source wets a contact with a wetting voltage. A current mirror circuit is connected across an input of the contact to provide a constant wetting current over a wide input voltage range. The input voltage can be varied over a range wide enough to include both AC voltages and DC voltages. The current mirror circuit maintains the constant wetting current during varying wetting voltage inputs across the input of the contact. A wetting voltage sensor senses the wetting voltage provided to the contact so that the status of the contact can be determined.

Disclosed is a method for optimizing a wetting current, for a device for monitoring sensors with contact switches including a current source and at least two switch/resistor assemblies (CT1/R1, CT2/R2) in parallel, including the following steps: the current source (A) supplies the circuit with a nominal current; if a voltage (Vm) measured across the terminals of the switch/resistor assemblies is greater than a threshold voltage (Vs), the threshold voltage being lower than the supply voltage of the current source and than the saturation voltage of the analog-to-digital converter (CAN), then the current source is stopped and a unit for discharging the circuit are implemented; and the current source supplies the circuit again with a supply current (Iwet_c) equal to the nominal current reduced by a predetermined increment. These two last steps are repeated until the measured voltage is lower than the threshold voltage.

Disclosed is a method for optimizing a wetting current, for a device for monitoring sensors with contact switches including a current source and at least two switch/resistor assemblies (CT1/R1, CT2/R2) in parallel, including the following steps: the current source (A) supplies the circuit with a nominal current; if a voltage (Vm) measured across the terminals of the switch/resistor assemblies is greater than a threshold voltage (Vs), the threshold voltage being lower than the supply voltage of the current source and than the saturation voltage of the analog-to-digital converter (CAN), then the current source is stopped and a unit for discharging the circuit are implemented; and the current source supplies the circuit again with a supply current (Iwet_c) equal to the nominal current reduced by a predetermined increment. These two last steps are repeated until the measured voltage is lower than the threshold voltage.