Means and method for detecting stray electrical energy, above a predetermined level, on a conductor

Claim 2

In combination with an electrical conductor forming a part of the firing circuit of an explosive device and subject to the possibility of having imposed thereon stray electrical energies at levels ranging from a given, low level to a given, higher level, a detector, associated with the electrical conductor, for detecting stray electrical energies occurring in the conductor, said detector comprising: a plurality of detecting means connectable in parallel to the conductor for detecting stray electrical energies of any polarities imposed thereon and including a first one of said means having an energy-detecting range including said given, higher level and further including at least one other means having an energy-detecting range extending lower than the first; sequencing means for causing the plurality of detecting means to operate automatically in a sequence until stray electrical energy is detected, beginning with connection of the first detecting means with the conductor and operation of the first detecting means and, upon no stray energy being detected, ending with connection with the conductor and operation of the one of said means having the lowest energy-detecting range; and means, connectable with respective ones of the detecting means, for indicating detection of stray electrical energy, for a period of time independent of the duration of the stray electrical energy, by any of the detecting means.

Claim 3

The stray energy detector claimed in claim 1 wherein the conductor is associated with a device having therein a plurality of potential stray energy sources, and the plurality of detecting means includes means for detecting stray energies imposed on said conductor by said sources.

Claim 4

The stray detector claimed in claim 1 wherein the conductor is associated with a device having therein a plurality of potential stray energy sources and wherein the plurality of detecting means includes means for detecting stray energies imposed on said conductor by sources in addition to those of said device.

Claim 5

The stray energy detector claimed in claim 1 wherein the first detecting means has an energy-detecting threshold corresponding to approximately 90 volts of electrical energy.

Claim 6

The stray energy detector claimed in claim 1 wherein at least one of said detecting means has an energy-detecting threshold corresponding to approximately 5 volts of electrical energy.

Claim 7

The stray energy detector claimed in claim 1 wherein at least one of said detecting means has an energy-detecting threshold corresponding to approximately 0.05 volts of electrical energy.

Claim 8

The stray energy detector claimed in claim 1 wherein said means for causing said detecting means to operate in a sequence includes means for automatically delaying the operation of at least one of said plurality of detecting means to provide adequate response time for at least one other, previously operated one of said detecting means.

Claim 9

The stray energy detector claimed in claim 1 wherein the plurality of detecting means includes at least three means for detecting stray electrical energies.

Claim 10

The stray energy detector claimed in claim 1 including protecting means associated with at least some of said detecting means for electrically disconnectIng the detector from the conductor in response to detecting operation of said at least some of said means, to protect subsequently operable ones of said detecting means from damage by energy of a high level.

Claim 11

The stray energy detector claimed in claim 1 and including means for electrically connecting the detecting means to the conductor to start the detecting sequence.

Claim 12

The stray voltage detector claimed in claim 1 wherein at least one detecting means includes a gas-filled lamp which conducts at a voltage level corresponding to the lower limit of the energy level desired to be detected by said at least one detecting means, said detector further including a photosensitive resistor positioned to be illuminated by said lamp, whereby resistance of the resistor is reduced in response to said illumination, said photosensitive resistor, upon its resistance being reduced, constituting a means for conducting current to the means for indicating detection of stray electrical energy.

Claim 13

The stray energy detector claimed in claim 1 wherein at least one of said detecting means includes an incandescent lamp which provides a given level of illumination in response to a voltage corresponding to an energy level to be detected and a photosensitive resistor positioned to be illuminated by said lamp, whereby the value of the resistance is reduced by said illumination, said photosensitive resistor positioned to be illuminated by said incandescent lamp constituting, upon its resistance being reduced, a means for conducting current to the means for indicating detection of stray electrical energy.

Claim 14

The stray energy detector claimed in claim 1 wherein the means for indicating detection of stray electrical energy includes an electrically operated indicating device, a source of electrical power, and switching means for connecting said source of power to said electrically operated device, and wherein at least one of said detecting means associated with a low, energy-detecting range has associated therewith means for providing electrical current to said switching means to cause said switching means to switch and to connect said source of power to said indicating means.

Claim 15

The stray voltage detector claimed in claim 1 wherein at least a portion of the stray energies which may possibly be imposed on said conductor is negative with respect to other stray energies which may possibly be imposed on said conductor, and at least one of said detecting means is for detecting said negative portion.

Claim 16

The stray energy detector claimed in claim 1 wherein the means for indicating detection of stray electrical energy includes a silicon-controlled rectifier having a gate electrode to which a predetermined amount of current must be supplied to cause the rectifier to conduct to activate said means for indicating detection, and at least some of said detecting means have associated therewith means for producing at least said predetermined amount of current for application to the rectifier gate in response to the detection of stray electrical energy by said associated detecting means.

Claim 17

The stray energy detector of claim 7, wherein said detecting means having the lowest energy detecting range comprises a sensing amplifier means for causing a constant polarity change in amplifier output voltage in response to nonrectified input pulses of either polarity.

Claim 18

A detector for stray electrical energies for use in association with an electrical conductor forming a part of the firing circuit of an explosive device and subject to the possibility of having imposed thereon stray electrical energies at energy levels ranging from a given, low level to a given, higher level, said detector comprising: a plurality of stray energy detecting means connectable in parallel to the conductor for detecting stray electrical energies imposed thereon and including a first one of said detecting means having an energy-detecting range including said given, higher level and further including at least one othEr of said detecting means having an energy-detecting range extending lower than the first; sequencing means for connecting the plurality of detecting means to the conductor in parallel and in a sequence which corresponds to the respective levels of the individual energy-detecting ranges of the respective detecting means and is limited to an order of effecting such connections beginning with connection of the first detecting means to the conductor and ending with connection to the conductor of the one of the detecting means having the lowest energy-detecting range; means responsive to individual operation of each of the detecting means for indicating detection of stray electrical energy by any one of the detecting means, the means for indicating detection of stray electrical energy comprising a means for indicating detection of stray electrical energy for a period of time independent of the duration of the stray electrical energy; and means for electrically isolating all of the detecting means from the conductor in response to operation of any of the detecting means to indicate the presence of stray electrical energy on the conductor.

Claim 19

A detector for stray electrical energies for use in association with an electrical conductor forming a part of the firing circuit of an explosive device and subject to the possibility of having imposed thereon stray electrical energies at energy levels ranging from a given, low level to a given, higher level, said detector comprising: a plurality of stray energy detecting means connectable in parallel to the conductor for detecting stray electrical energies imposed thereon and including a first one of said detecting means having an energy-detecting range including said given, higher level and further including at least one othEr of said detecting means having an energy-detecting range extending lower than the first; sequencing means for connecting the plurality of detecting means to the conductor in parallel and in a sequence which corresponds to the respective levels of the individual energy-detecting ranges of the respective detecting means and is limited to an order of effecting such connections beginning with connection of the first detecting means to the conductor and ending with connection to the conductor of the one of the detecting means having the lowest energy-detecting range; means responsive to individual operation of each of the detecting means for indicating detection of stray electrical energy by any one of the detecting means, the means for indicating detection of stray electrical energy comprising a means for indicating detection of stray electrical energy for a period of time independent of the duration of the stray electrical energy; and means for electrically isolating all of the detecting means from the conductor in response to operation of any of the detecting means to indicate the presence of stray electrical energy on the conductor.