Abstract: A system and method for detecting a phase-to-ground fault in an AC electrical machine operates to receive measurements of three-phase voltages and currents provided to the AC electrical machine, compute at least one of a zero sequence component and a negative sequence component of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (FSI) based on the zero or negative sequence component of voltage and current, so as to identify a phase-to-ground fault in the AC electrical machine. Calculating the FSI further includes determining a total value of the zero or negative sequence current, determining a noise-contributed value of the zero or negative sequence current included in the total value, determining a compensated value of the zero or negative sequence current based on the total value and the noise-contributed value, and calculating the FSI based on the compensated value.

Abstract: A system and method for detecting a phase-to-ground fault in an AC electrical machine operates to receive measurements of three-phase voltages and currents provided to the AC electrical machine, compute at least one of a zero sequence component and a negative sequence component of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (FSI) based on the zero or negative sequence component of voltage and current, so as to identify a phase-to-ground fault in the AC electrical machine. Calculating the FSI further includes determining a total value of the zero or negative sequence current, determining a noise-contributed value of the zero or negative sequence current included in the total value, determining a compensated value of the zero or negative sequence current based on the total value and the noise-contributed value, and calculating the FSI based on the compensated value.

Abstract: A control system includes: a controller configured to: access an estimated torque and estimated speed of a motor mechanically coupled to an impeller of a centrifugal machine; access at least one set of pre-determined performance data values associated with a known speed of the impeller, where each set of pre-determined performance data values includes: a plurality of flowrate values and a plurality of performance metric values; determine an operating point of the centrifugal machine based on the estimated torque, the estimated speed, and the at least one set of pre-determined performance data values; compare the determined operating point to a best efficiency point (BEP) associated with the centrifugal machine; and determine whether to change the speed of the motor based on the comparison.

Abstract: A system and method for detecting a phase-to-ground fault in an AC electrical machine operates to receive measurements of three-phase voltages and currents provided to the AC electrical machine, compute at least one of a zero sequence component and a negative sequence component of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (FSI) based on the zero or negative sequence component of voltage and current, so as to identify a phase-to-ground fault in the AC electrical machine. Calculating the FSI further includes determining a total value of the zero or negative sequence current, determining a noise-contributed value of the zero or negative sequence current included in the total value, determining a compensated value of the zero or negative sequence current based on the total value and the noise-contributed value, and calculating the FSI based on the compensated value.

Abstract: A system for locating a ground fault in an HRG power distribution system includes an HRG pulsing system having a ground fault sensor to detect a ground fault, a pulsing contactor to introduce a pulsing current into the power distribution system, and a controller to control the pulsing contactor to introduce the pulsing current into the power distribution system in response to a ground fault detection by the ground fault sensor. Current sensors in the power distribution system monitor three-phase current signals on conductors of the power distribution system, with the current sensors positioned on distribution networks in the power distribution system and at a protection device included on each respective distribution network. A processor associated with each protection device and operably connected to the current sensors thereat receives signals from the current sensors for identifying a location of a ground fault in the power distribution system.

Abstract: A system and method for estimating operating characteristics of an induction motor is disclosed. The system includes a motor control device that is electrically connectable between a motor and a power source. The motor control device includes a plurality of switching devices comprising at least one thyristor corresponding to a respective phase of the motor. The motor control device also includes a controller programmed to disconnect the power source from the motor for a predetermined time period following a first plurality of cycles of a mains phase voltage of the power source. The controller is further programmed to measure a back-emf voltage during the predetermined time period, estimate an operating characteristic of the motor from the measured back-emf voltage, and trigger the plurality of switching devices to reconnect the power source to the motor following estimation of the operating characteristic.

Abstract: A system and method for detecting a phase-to-ground fault in an AC electrical machine operates to receive measurements of three-phase voltages and currents provided to the AC electrical machine, compute at least one of a zero sequence component and a negative sequence component of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (F SI) based on the zero or negative sequence component of voltage and current, so as to identify a phase-to-ground fault in the AC electrical machine. Calculating the FSI further includes determining a total value of the zero or negative sequence current, determining a noise-contributed value of the zero or negative sequence current included in the total value, determining a compensated value of the zero or negative sequence current based on the total value and the noise-contributed value, and calculating the FSI based on the compensated value.

Abstract: A system and method for detecting, localizing and quantifying stator winding faults in AC electrical machines is disclosed. A diagnostic system configured to detect a stator winding fault in an AC electrical machine includes a processor programmed to receive measurements of three-phase voltages and currents provided to the AC electrical machine from voltage and current sensors associated with the electrical distribution circuit, compute positive, negative and zero sequence components of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (FSI) based on at least a portion of the positive, negative and zero sequence components of voltage and current, wherein calculating the FSI further comprises identifying a voltage gain in one or more phases of the AC electrical machine due to a stator winding fault and localizing the stator winding fault to one or more phases in the AC electrical machine.

Abstract: A system and method for detecting and localizing excess voltage drop in single or multiple phases of three-phase AC circuits is disclosed. An electrical distribution circuit is provided that includes an input connectable to an AC source, an output connectable to terminals of an electrical machine, the output configured to provide three-phase voltages and currents to the electrical machine, and a diagnostic system configured to detect an excess voltage drop (EVD) in the electrical distribution circuit. The diagnostic system includes a processor that is programmed to receive measurements of the three-phase voltages and currents provided to the electrical machine, compute a negative sequence voltage from the three-phase voltages and currents, determine a localization reference phase angle for each phase based in part on the three-phase voltages and currents, and calculate an EVD in the electrical distribution circuit based on the negative sequence voltage and the localization reference phase angles.

Abstract: A system for locating a ground fault in an HRG power distribution system includes an HRG pulsing system having a ground fault sensor to detect a ground fault, a pulsing contactor to introduce a pulsing current into the power distribution system, and a controller to control the pulsing contactor to introduce the pulsing current into the power distribution system in response to a ground fault detection by the ground fault sensor. Current sensors in the power distribution system monitor three-phase current signals on conductors of the power distribution system, with the current sensors positioned on distribution networks in the power distribution system and at a protection device included on each respective distribution network. A processor associated with each protection device and operably connected to the current sensors thereat receives signals from the current sensors for identifying a location of a ground fault in the power distribution system.

Abstract: A system for locating a ground fault in a high resistance grounded (HRG) power distribution system includes a pulsing circuit configured to introduce a pulse current into the distribution system and current sensors adapted to monitor three-phase current signals present on conductors of the distribution system, with the current sensors positioned on a number of distribution networks included in the HRG power distribution system and at a protective device included on each respective distribution network. A processor associated with each protective device receives signals from the current sensors for identifying a location of the ground fault in the HRG power distribution system, with the processor associated with each protective device receiving measurements of the three-phase current signals from the current sensors over a plurality of cycles and identifying a pattern of interest in the three-phase current signals across the plurality of cycles in order to detect a ground fault.

Abstract: A system and method for estimating operating characteristics of an induction motor is disclosed. The system includes a motor control device that is electrically connectable between a motor and a power source. The motor control device includes a plurality of switching devices comprising at least one thyristor corresponding to a respective phase of the motor. The motor control device also includes a controller programmed to disconnect the power source from the motor for a predetermined time period following a first plurality of cycles of a mains phase voltage of the power source. The controller is further programmed to measure a back-emf voltage during the predetermined time period, estimate an operating characteristic of the motor from the measured back-emf voltage, and trigger the plurality of switching devices to reconnect the power source to the motor following estimation of the operating characteristic.

Abstract: A system and method for automatically defining and tuning operating parameters for a motor control device with minimal or no operator input is disclosed. The system includes a motor control device electrically connectable to an AC motor and a controller that is programmed to define a motor start-up function based on a rated current of the motor, the motor start-up function comprising an initial torque factor and an initial ramp time. The controller also triggers switching devices of the motor according to the motor start-up function to inject current into the motor during a first trial run, monitors operating conditions of the motor and motor control device during the first trial run, modifies the motor start-up function based on the monitored operating conditions, and triggers the plurality of switching devices according to the modified motor start-up function to inject current into the motor during a subsequent trial run.

Abstract: A system and method for detecting and localizing excess voltage drop in single or multiple phases of three-phase AC circuits is disclosed. An electrical distribution circuit is provided that includes an input connectable to an AC source, an output connectable to terminals of an electrical machine, the output configured to provide three-phase voltages and currents to the electrical machine, and a diagnostic system configured to detect an excess voltage drop (EVD) in the electrical distribution circuit. The diagnostic system includes a processor that is programmed to receive measurements of the three-phase voltages and currents provided to the electrical machine, compute a negative sequence voltage from the three-phase voltages and currents, determine a localization reference phase angle for each phase based in part on the three-phase voltages and currents, and calculate an EVD in the electrical distribution circuit based on the negative sequence voltage and the localization reference phase angles.

Abstract: A system and method for detecting, localizing and quantifying stator winding faults in AC electrical machines is disclosed. A diagnostic system configured to detect a stator winding fault in an AC electrical machine includes a processor programmed to receive measurements of three-phase voltages and currents provided to the AC electrical machine from voltage and current sensors associated with the electrical distribution circuit, compute positive, negative and zero sequence components of voltage and current from the three-phase voltages and currents, and calculate a fault severity index (FSI) based on at least a portion of the positive, negative and zero sequence components of voltage and current, wherein calculating the FSI further comprises identifying a voltage gain in one or more phases of the AC electrical machine due to a stator winding fault and localizing the stator winding fault to one or more phases in the AC electrical machine.

Abstract: A system and method for determining rotor speed of an AC induction machine is disclosed. The system is programmed to estimate a rotor speed of the induction machine according to a linear speed estimation algorithm and based on name plate information (NPI) of the induction machine and parameters of the AC induction machine during operation thereof. The rotor speed estimation system is also programmed to estimate a rotor speed of the AC induction machine according to a frequency-domain signal processing algorithm and determine if the rotor speed estimated thereby is valid. If the rotor speed estimated by the frequency-domain signal processing algorithm is valid, then a tuned rotor speed of the AC induction machine is estimated according to the linear speed estimation algorithm and based, in part, on the rotor speed estimated by the frequency-domain signal processing algorithm.

Abstract: A system and method for automatically defining and tuning operating parameters for a motor control device with minimal or no operator input is disclosed. The system includes a motor control device electrically connectable to an AC motor and a controller that is programmed to define a motor start-up function based on a rated current of the motor, the motor start-up function comprising an initial torque factor and an initial ramp time. The controller also triggers switching devices of the motor according to the motor start-up function to inject current into the motor during a first trial run, monitors operating conditions of the motor and motor control device during the first trial run, modifies the motor start-up function based on the monitored operating conditions, and triggers the plurality of switching devices according to the modified motor start-up function to inject current into the motor during a subsequent trial run.

Abstract: A system and method for detecting excess voltage drop (EVD) in a three-phase electrical distribution circuit includes a diagnostic system comprising a processor that is programmed to receive three-phase voltages and currents provided to terminals of the electrical machine, determine fundamental components of the three-phase voltages and currents provided to the terminals, and compute positive, negative, and zero sequence currents from the fundamental components.

Abstract: A system and method for detecting excess voltage drop (EVD) in a three-phase electrical distribution circuit includes a diagnostic system comprising a processor that is programmed to receive three-phase voltages and currents provided to terminals of the electrical machine, determine fundamental components of the three-phase voltages and currents provided to the terminals, and compute positive, negative, and zero sequence currents from the fundamental components.

Abstract: A system and method for determining rotor speed of an AC induction machine is disclosed. The system is programmed to estimate a rotor speed of the induction machine according to a linear speed estimation algorithm and based on name plate information (NPI) of the induction machine and parameters of the AC induction machine during operation thereof. The rotor speed estimation system is also programmed to estimate a rotor speed of the AC induction machine according to a frequency-domain signal processing algorithm and determine if the rotor speed estimated thereby is valid. If the rotor speed estimated by the frequency-domain signal processing algorithm is valid, then a tuned rotor speed of the AC induction machine is estimated according to the linear speed estimation algorithm and based, in part, on the rotor speed estimated by the frequency-domain signal processing algorithm.