Abstract: A voltage sensor consists of a number of capacitive voltage sensors coupled to test points in an electrical power system. The outputs of the voltage sensors are digitized and processed by a digital processor, which determines a normal value for the monitored AC voltages, and then determines if the monitored AC voltages are acceptable based on variations from the normal value.

Abstract: A voltage sensor consists of a number of capacitive voltage sensors coupled to test points in an electrical power system. The outputs of the voltage sensors are digitized and processed by a digital processor, which determines a normal value for the monitored AC voltages, and then determines if the monitored AC voltages are acceptable based on variations from the normal value.

Abstract: A safety device is disclosed. The safety device includes a protective component wearable on a user's head. The safety device further includes a display unit configured to present status information at position in the periphery of the field of view of the user. The safety device includes a communications unit connectable to a wireless communication network and configured to send or receive status information. In certain embodiments, the safety device is a breathing apparatus or a head protection device. A method of presenting information to a user of the breathing apparatus is also disclosed.

Abstract: A fault indicator for indicating the occurrence of a fault in an electrical conductor is programmable, such as in the field, by placing a magnet in proximity to the housing of the fault indicator. A data processor senses the changed state of a magnetic switch and, after a predetermined delay, initiates a programming routine to enable selection of one of a plurality of trip settings for the fault indicator. During programming, display LEDs flash once for programming of the first trip setting, twice for setting of the second trip setting, and so forth. Removal of the magnet from proximity to the fault indicator while at the desired trip setting will result in programming of the fault indicator to that trip setting.

Abstract: A fault indicator for indicating the occurrence of a fault in an electrical conductor is automatically configured for an overhead application or for an underground application. The fault indicator has a housing, a battery, a display for indicating the occurrence of a fault, a current sensor for sensing the load current in a monitored conductor, and electromagnetic field sensor to sense the electromagnetic field about the conductor, and a microcontroller for determining whether a fault condition occurred, for determining the magnitude of the electromagnetic field, and for configuring the fault indicator in the overhead configuration if the electromagnetic field is above a predetermined magnitude or configuring the fault indicator for the underground mode if the field is below the predetermined magnitude.

Abstract: A fault indicator for indicating the occurrence of a fault in an electrical conductor has a plurality of trip settings, such as in the range of 50 A to 1200 A, that is automatically calibrated. The fault indicator includes a housing, a battery, an illuminated display, such as LEDs, a current sensor for sensing the load current in the conductor and a microcontroller that receives a current signal from the current sensor to determine the load current. In the calibration mode, a known load current is passed through the conductor, the microcontroller selects the trip level that is related to the load current, determines the load current from the current signal, and sequentially calibrates each of the plurality of trip levels for the respective known load currents. The calibration information is stored in memory. The illuminated display provides a distinctive pattern to indicate that each trip setting has been calibrated.

Abstract: A fault indicator for indicating the occurrence of a fault in an electrical conductor has a housing, a high capacity battery, a display for indicating the occurrence of a fault, a current sensor for sensing the load current in a monitored conductor a microcontroller for determining the load current, for selecting one of a plurality of trip settings, such as in several steps between 50 A and 1200 A, based upon the determined load current and for determining that a fault condition occurred when the load current exceeds the trip setting. The selected trip setting is stored in memory. The load current is periodically sampled and the trip setting is changed if the load current falls in a different range. The display may include permanent and temporary fault indicating LEDs and additional internal LEDs that cause the housing to glow or flash at nighttime, or a target style display may be used. Upon the load current exceeding the trip setting, the microcontroller begins flashing the permanent fault LEDs.