A transient voltage surge suppression system incorporating a current protection device comprised of a voltage sensitive and a thermal sensitive device. The voltage sensitive device has a predetermined voltage rating and increases in temperature as voltage applied thereto exceeds its voltage rating. The thermal sensitive device is responsive to heating of the voltage sensitive device to break an electrical current path if an overvoltage condition sensed by the voltage sensitive device exceeds the voltage rating of the voltage sensitive device.

Circuit protection device

Apparatus and methods for controlling and communicating with one or more tools in a downhole tool string including a tractor, an auxiliary tractor tool, a logging tool, a safety sub, a release mechanism, a unit containing sensors for monitoring downhole conditions, a setting tool, and a perforating gun. Control and communication are accomplished by sending signals from the surface to control switches in the control units on the tool, with redundant switches for safety, to state machines in the respective control units, each state machine returning a signal verifying switch status to the surface. The state machine need not return a signal including a unique identifier.

Tractor communication/control and select fire perforating switch simulations

A protection apparatus (48) is provided which in addition to protecting electronic equipment (5) from overvoltage transients is also able to provide an indication of whether or not said transients are due to impedances associated with poor earthing. In one embodiment the protection apparatus (48) includes an input terminal (42), an output terminal (60) and a ground reference terminal (62) with a transient blocking unit (50) arranged to isolate the output terminal (60) in response to the destructive transient voltages. A gas discharge tube (46) is provided to conduct transient currents associated with the destructive transient voltages to the earth reference connection point (62); and an indicator (58), such as a fuse or circuit breaker is placed in series with the transient blocking unit (50) to indicate the presence of a voltage resulting from an interaction of the transient currents with an earthing impedance.

A protection and indication apparatus

A replacement wrist band may include a display and at least one replaceable module formed on the wrist band itself.

Smart Watch Band

A fiber optic splice closure permits grounding a fiber optic backbone cable but allows for propagation of cable-locating signals along the full length of the backbone cable and along fiber optic spur cables spliced to the backbone cable in the closure. An electrically conductive sheath of the backbone cable is coupled to ground through a surge protector and through a resistor to a conductive member of each spur cable. The terminating end of the spur cable is hard grounded at the customer site. The surge protector and resistor are mounted outside a sealed splice chamber of the closure.

Fiber optic splice closure and protection apparatus

This invention relates to a communication line filter for use in series with communication lines. The communication line filter provides for surge protection from voltage spikes and provides frequency filtering to remove selected interference signals from other radiating sources. The communication line filter comprises: two signal conductors linked together by a fuse; a common signal ground; and two shunts for shunting a surge current between the signal conductors and the common signal ground. The shunts provide protection from short duration voltage spikes while the fuse provides protection from longer duration overvoltages. The communication line filter functions effectively, independent of the direction of current flow along the communication line with respect the line filter. The two shunts and the fuse are selected to provide the required capacitance and impedance respectively, to form a suitable frequency notch filter.

Frey Wilfred

Papers

Bidirectional communication line filter and surge protector