Abstract: An electrical device protection apparatus, such as an overload relay, can include a microprocessor 102 that can receive a wide range of current signals from a current transformer or other current sensor. Also microprocessor 102 can employ a voltage sensor 112 to measure line voltage, for representing true power, and as a power supply 114 source for the microprocessor 102. The microprocessor can then generate annunciation signals 118, control signals 120, and/or communication signals 122 as necessary for the control and/or protection of an attached electrical device.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A highly accurate relative humidity sensing device includes a sensory unit having a humidity sensitive capacitor which has a capacitance which changes as a function of relative humidity. The sensor unit is housed in a tubular unit which is inserted through an aperture into the environment to be measured which is typically a duct or the like. The unit is constructed for easy removability. A housing having a central aperture is bolted to the duct and the tube containing the sensor is inserted through the aperture into a hole drilled into the sidewall of the duct. The cylinder holding the sensor is grasped by a releasably detachable securing structure. By releasing the securing structure, the cylinder may be withdrawn from the duct for replacement of the sensor.

Abstract: A humidity sensing device comprises a sensor unit including a humidity sensitive capacitor having a capacitance which changes as a function of relative humidity, an oscillator circuit including the humidity sensitive capacitor wherein the output frequency of the oscillator circuit is a function of capacitance, and a sensor memory unit having stored calibration data for said humidity sensitive capacitor. A data processing unit is coupled to the sensor unit and includes a data processing circuit coupled to an output of said oscillator circuit, wherein said data processing circuit provides an output indicative of relative humidity as modified by the calibration data received by and stored in another memory unit as associated with such data processing circuit.