Sigma Instruments, Inc.

Pacific Scientific Company

Thomas Yeh

Joseph R Thibodeau

The disclosed faulted current indicator ignores temporary overloads and transients by inhibiting any trip resulting from an overcurrent signal until a disabling circuit senses that a fuse or circuit breaker has reduced the line current to zero.

Faulted current indicator with protection against temporary overloads

The disclosed fault indicator which senses current in a cable, resets in response to a minimum current and trips when the current exceeds a predetermined multiple above the average value of the current. A trip circuit senses the average value by periodic current sampling or by continuous current averaging. Maximum and minimum trip setting limit the excursion of the multiple of the average value.

Autoranging faulted circuit indicator

The disclosed fault indicator which senses current in a cable, resets in response to a minimum current and arms a trip arrangement in response to current rising a predetermined amount with respect to time. If the rising current also opens a circuit breaker within a predetermined time and cuts off current to the cable, the indicator trips. If no zero current occurs within the time period, the trip arrangement is disarmed for the next current rise.

Adaptive trip fault current indicator

In the disclosed fault indicator a sensing device is arranged for location in the magnetic field surrounding a conductor, an electronic device responsive to the sensing device assumes a first state in response to the sensing device sensing a trip condition and remains in the first state until set to a second state, a signaling device coupled to the electronic device serves for generating a signal only in response to the electronic device being in the first state, and a timing device responsive to the electronic device assumes the first state serves for setting the electronic device to the second state after a predetermined period. The sensing device is an inductive sensor, preferably a coil with an axis transverse to the conductor. In one embodiment an inrush restraint circuit renders the electronic device insensitive to inrush currents.

Fault indicator with timing control

A fault indicator which senses current in a cable, resets in response to a minimum current and arms a trip arrangement in response to current rising a predetermined amount with respect to time. If the rising current also opens a circuit breaker within a predetermined time and cuts off current to the cable, the indicator trips. If no zero current occurs within the time period, the trip arrangement is disarmed for the next current rise.

Current adaptive fault indicator

A faulted circuit indicator includes an inrush restraint circuit that suppresses a trip signal when an inrush current rises from below a minimum value to a trip value within a predetermined time and then drops again to another value such as the trip value. According to various aspects the restraint ends after a fixed time or after a variable time. According to another aspect a second trip circuit overrides the inrush restraint circuit when the current rises a given amount beyond the first trip value.

Faulted current indicators and inrush restraints therefor

In the disclosed fault detector, a casing has a u-shaped portion for receiving a cable and a portion extending from the u-shaped portion. A screw is mounted on said portion. A pressure device is mounted on the end of the screw and directed toward the u-shaped portion for holding the cable in the u-shaped portion. A magnetic lamination passes through the u-shaped portion. The pressure device is made of a magnetic material and a coil surrounds said laminations.

Fault indicator with hot stick clamping mechanism

The disclosed faulted current indicator senses current in a line having a breaker or fuse, and avoids tripping in response to current inrush signals by producing a trip signal in response to an overcurrent occurring for an overcurrent duration which is inversely related to the magnitude of the overcurrent and is faster than the overcurrent operating time of the breaker or fuse. In one embodiment, this involves operating a current protection device in response to an overcurrent occurring for a second overcurrent duration inversely related to the magnitude of the overcurrent according to a first characteristic, and adjusting the first overcurrent duration to follow a second characteristic having variations substantially the same as the first characteristic but having a shorter first overcurrent duration than the second overcurrent duration.

Faulted current indicator with inrush restraint

In the disclosed outdoor lighting control, angular reflectors (52) direct vertical light passing through a translucent dome (38) onto a vertically oriented photocell (24) and a rigid vertically-adjustable sheet (54) between the photocell and the reflectors regulates the operating point of the photocell. The backs of the reflectors, and a socket (14) projecting vertically from a base (12) under the dome, shield the vertical photocell from horizontal light.

Growing community of inventors

South Weymouth, MA, United States of America

Thomas Yeh