Abstract:
A system includes a relay system and a controller. The relay system includes a plurality of relays, each having a first contact on an input side of the respective relay, the input side coupled to a power source, a second contact on a load side of the respective relay coupled to a load, and a spanner configured to close the first and second contacts of the respective relay when activated by a close signal. The load sides of each of the respective relays are coupled through their respective loads. The controller is configured to measure a voltage between a spanner of a first relay and an input side of a second relay. Based on the voltage between the spanner of the first relay and the input side of the second relay, the controller determines whether an electrical weld of one of the contacts of the first relay exists.
Abstract:
A non-transitory, computer-readable medium may include instructions executable by at least one processor in a computing device to cause the processor to perform operations that include transmitting, to a first power source, a command to provide power to a coil of a switching device with a fixed current profile. The operations also include receiving one or more voltage measurements associated with the coil during a period of time, determining whether the voltage measurements associated with the coil indicate that one or more movable contacts of the switching device are at least partially welded to one or more contacts of an electric circuit, and transmitting an additional command to a second power source to disconnect a current to the coil in response to determining that the voltage measurements indicate that the movable contacts of the switching device are at least partially welded to the contacts of the electric circuit.
Abstract:
A system includes a relay system and a controller. The relay system includes a relay having a first contact on an input side of the relay, the input side coupled to a power source, and a second contact on a load side of the relay coupled to a load. The controller is configured to monitor a current flow from the power source through the relay, transmit a close signal to the relay, and to transmit an open signal to the relay. Based on the current flow through the relay following the open signal, determine whether an electrical weld of one of the first contact and the second contact of the relay exists.
Abstract:
A system includes a relay system and a controller. The relay system includes a plurality of relays. The controller is configured to transmit a close signal to a first relay of the plurality of relays, and to transmit a pulse signal to a second relay of the plurality of relays. The pulse signal is configured to have a sufficient electrical magnitude and duration to close the second relay when the second relay has an electrical weld, and to have an insufficient electrical magnitude and duration to close the first contact and the second contact of the second relay when the second relay has no electrical weld. The controller is also configured to measure a current flow through the second relay in response to the pulse signal; and based on the current flow through the second relay, determine whether the electrical weld exists in the second relay.
Abstract:
Systems and methods are provide for detecting weld relay devices within a switching device by: closing one or more first relay devices, wherein the one or more first relay devices are configured to selectively connect and disconnect a first phase of electric power from a power source; opening one or more second relay devices and one or more third switches; detecting whether there is electric current through the one or more second relay devices; and in response to detecting that there is electric current through the one or more second relay devices, determining that the one or more second relay devices are welded.
Abstract:
A device includes an armature, a coil, and a circuit. The armature is configured to move between a close position that electrically couples the armature to a contact and an open position that is not electrically coupled to the contact. The coil is configured to release a voltage configured to de-magnetize the coil, thereby causing the armature to move from the close position to the open position. The circuit is configured to provide reverse driving current to the coil during a period of time when the armature moves from the close position to the open position.
Abstract:
Current transformer circuit systems and methods dynamically switch a load. The current transformer circuit includes a current source circuit including at least one current transformer to produce a current output wave. A burden circuit includes at least one burden resistor and a voltage sensor, at least a portion of the current output wave to be passed through the burden resistor, and the voltage sensor to sense a voltage across the respective at least one burden resistor. A switch circuit includes at least one switch, the switch circuit coupled to the burden circuit. A microcontroller circuit includes a microcontroller, the microcontroller circuit coupled to a power circuit and the switch circuit, the microcontroller being configured to control the switch circuit to dynamically switch a secondary loading of the at least one current transformer between the burden resistor and a low resistance load.
Abstract:
A method of estimating stator resistance of an induction motor is provided. The method includes applying voltage pulses through two phase paths of the motor for a plurality of electrical cycles to inject current in the motor, wherein the voltage pulses are applied until rotor flux of the motor is substantially stabilized and measuring stator voltage and stator current in response to the applied voltage pulses for each of the plurality of electrical cycles. The method also includes calculating the stator resistance based upon the measured stator voltages and the stator currents.
Abstract:
A method may include receiving a command to move one or more armatures of a switching device from a first position that electrically couples a first contact to a second contact to a second position that electrically uncouples the first contact from the second contact. The method may also include selecting a current zero-crossing point along an electric waveform indicative of a change in current through the first contact and the second contact as a synchronization point, determining a predicted current zero-crossing point by adding a period measurement associated with a previously detected current zero-crossing point or a previously detected line-to-line crossing point in the electric waveform to the synchronization point, and transmitting a command to the switching device to move the armatures from the first position to the second position before or at the predicted current zero-crossing point.
Abstract:
A method may include receiving a command to move one or more armatures of a switching device from a first position that electrically couples a first contact to a second contact to a second position that electrically uncouples the first contact from the second contact. The method may also include selecting a current zero-crossing point along an electric waveform indicative of a change in current through the first contact and the second contact as a synchronization point, determining a predicted current zero-crossing point by adding a period measurement associated with a previously detected current zero-crossing point or a previously detected line-to-line crossing point in the electric waveform to the synchronization point, and transmitting a command to the switching device to move the armatures from the first position to the second position before or at the predicted current zero-crossing point.