Abstract: A frost monitor for HVAC&R systems detects efficiency degradations indicative of coil icing or frosting conditions by modeling compressor input power. The model uses temperature and compressor input power parameter measurements to predict expected compressor input power parameter values. Efficiency degradations are detected by comparing compressor power or current as predicted by the model against measured power or current. Deviations of the measured power parameter values from the predicted power parameter values by a predefined threshold reflect efficiency degradations that may be due to ice or frost accumulation on system coils. Such efficiency degradations may then be used to initiate a defrost cycle in the system.

Abstract: A frost monitor for HVAC&R systems detects efficiency degradations indicative of coil icing or frosting conditions by modeling compressor input power. The model uses temperature and compressor input power parameter measurements to predict expected compressor input power parameter values. Efficiency degradations are detected by comparing compressor power or current as predicted by the model against measured power or current. Deviations of the measured power parameter values from the predicted power parameter values by a predefined threshold reflect efficiency degradations that may be due to ice or frost accumulation on system coils. Such efficiency degradations may then be used to initiate a defrost cycle in the system.

Abstract: Power measurement by tracking of a voltage cycle when voltage and current measurements are taken at different locations on an AC power line, with the devices taking the measurements interconnected by an asynchronous data network. In general, a synchronization/timing message is sent from the voltage sensing side to the current sensing side, with the synchronization/timing message being transmitted at a predetermined point in the periodic voltage cycle. The receipt of the synchronization/timing message by the current sensing side may be used to re-synchronize an internal model of the voltage cycle maintained by the current sensing side to the measured voltage cycle. The predetermined point in the voltage cycle may be the zero-crossing point, or other point, of the voltage cycle.

Abstract: Power measurement by tracking of a voltage cycle when voltage and current measurements are taken at different locations on an AC power line, with the devices taking the measurements interconnected by an asynchronous data network. In general, a synchronization/timing message is sent from the voltage sensing side to the current sensing side, with the synchronization/timing message being transmitted at a predetermined point in the periodic voltage cycle. The receipt of the synchronization/timing message by the current sensing side may be used to re-synchronize an internal model of the voltage cycle maintained by the current sensing side to the measured voltage cycle. The predetermined point in the voltage cycle may be the zero-crossing point, or other point, of the voltage cycle.

Abstract: A point-of-use energy status indicator monitoring the presence or absence of energy at a monitored device that is required for proper operation of a point-of-use device. The point-of-use indicator being in two-way communication with a status determining device that monitors the monitored device. The status determining device being capable of overriding a utility or energy management system curtailment of energy to the monitored device in response to receiving a signal from a means for overriding located in the point-of-use energy status indicator.

Abstract: A point-of-use energy status indicator monitoring the presence or absence of energy at a monitored device that is required for proper operation of a point-of-use device. The point-of-use indicator being in two-way communication with a status determining device that monitors the monitored device. The status determining device being capable of overriding a utility or energy management system curtailment of energy to the monitored device in response to receiving a signal from a means for overriding located in the point-of-use energy status indicator.

Abstract: Circuit for determining the presence or absence of a remotely controlled circuit beaker connection to a control circuit and the current state of an internal operating device of a remotely controlled circuit breaker connected to a control circuit.

Abstract: Circuit for determining the presence or absence of a remotely controlled circuit beaker connection to a control circuit and the current state of an internal operating device of a remotely controlled circuit breaker connected to a control circuit.

Abstract: An independent automatic shedding system that automatically allows any combination of loads to powered under limited power availability (such as a standby power source) without overloading the generator or rewiring, while contributing to the stability of the power grid. A motorized disconnection actuation mechanism under control of a controller disconnects or recloses the contacts of a branch circuit breaker. A sensor detects the presence or absence of a power source and the type of power source, which is classified according to its type. A power source classification program is executed by the controller that interprets the sensor data and causes disconnection or reclosing of the disconnection actuation mechanism depending on a desired status (ON or OFF) of the branch circuit breaker when standby power is available. Conventional circuit protection is provided an optional advanced circuit protection such as ground or arc fault circuit interruption.

Abstract: An economical digital voltage sag compensator for overcoming sags in distributed electrical power. The voltage sag compensator employs an inexpensive micro-controller, a full wave bridge rectifier, a DC power supply, a voltage divider and an output switch. The micro-controller continuously monitors and evaluates, with respect to a setpoint measured in volt-seconds, the rectified DC voltage. At regularly spaced trigger events, as determined by the micro-controller, the micro-controller concurrently monitors the rectified DC voltage, evaluates the monitored voltage with respect to the setpoint, produces an output signal and sends that output signal to the output switch. The output switch supplies an electrical device, connected electrically in series with the full wave bridge rectifier and the output switch, with a constant average current of sufficient level to maintain the electrical device in a desired operating condition.

Abstract: A microcontroller-based system to detect ground-fault and grounded-neutral conditions in a monitored circuit of an electrical distribution system having line and neutral conductors. The system includes a single sensor producing an output signal responsive to current flow in both the line and neutral conductors of the monitored circuit, and a microcontroller receiving the sensor output signal and initiating the generation of a circuit status signal indicating one of a normal operating condition, a ground-fault condition or a grounded-neutral condition in the monitored circuit. The microcontroller is programmed to continuously test for ground-fault conditions by evaluating the sensor output signal and, at selected intervals, test for grounded-neutral conditions by evaluating the sensor's output signal response to a microcontroller initiated ping in the sensor circuit.

Abstract: A microcontroller-based system to detect ground-fault and grounded-neutral conditions in a monitored circuit of an electrical distribution system having line and neutral conductors. The system includes a single sensor producing an output signal responsive to current flow in both the line and neutral conductors of the monitored circuit, and a microcontroller receiving the sensor output signal and initiating the generation of a circuit status signal indicating one of a normal operating condition, a ground-fault condition or a grounded-neutral condition in the monitored circuit. The microcontroller is programmed to continuously test for ground-fault conditions by evaluating the sensor output signal and, at selected intervals, test for grounded-neutral conditions by evaluating the sensor's output signal response to a microcontroller initiated ping in the sensor circuit.

Abstract: An economical digital voltage sag compensator for overcoming sags in distributed electrical power. The voltage sag compensator employs an inexpensive micro-controller, a full wave bridge rectifier, a DC power supply, a voltage divider and an output switch. The micro-controller continuously monitors and evaluates, with respect to a setpoint measured in volt-seconds, the rectified DC voltage. At regularly spaced trigger events, as determined by the micro-controller, the micro-controller concurrently monitors the rectified DC voltage, evaluates the monitored voltage with respect to the setpoint, produces an output signal and sends that output signal to the output switch. The output switch supplies an electrical device, connected electrically in series with the full wave bridge rectifier and the output switch, with a constant average current of sufficient level to maintain the electrical device in a desired operating condition.

Abstract: A power line communications apparatus and method for providing communications over power leads connecting two pieces of electrical equipment. One power lead is split into similarly sized first and second parallel conductors. The first and second conductors pass through a current transformer, the first conductor having a load current flow opposite the second conductor with respect to the current transformer. The transmitted communications signal is applied to the secondary of the current transformer and is induced on the primary of the transformer, namely a loop formed by the first and second conductors. A second current transformer serves as a receiving transducer and senses the communications signal on the first and second conductors.

Abstract: A power line communications apparatus and method for providing communications over power leads connecting two pieces of electrical equipment. One power lead is split into similarly sized first and second parallel conductors. The first and second conductors pass through a current transformer, the first conductor having a load current flow opposite the second conductor with respect to the current transformer. The transmitted communications signal is applied to the secondary of the current transformer and is induced on the primary of the transformer, namely a loop formed by the first and second conductors. A second current transformer serves as a receiving transducer and senses the communications signal on the first and second conductors.