Apparatus including a piezoelectric element for checking the operativeness of a voltage tester

Claim 2

In a voltage tester of the type comprising one or more contact elements for engaging a conductor to be tested for its voltage condition, an insulated armature for capacitively cooperating with ground, and an indicating circuit including glow discharge means connected between said contact elements and said armature, the improvement which comprises the provision of means for checking the operativeness of said voltage tester comprising a piezoelectric device, a member for applying a mechanical load thereto to produce a voltage between opposed terminals of the piezoelectric device, electrical leads extending from said terminals, and a spark-gap in one of said leads, said leads being arranged for connection across said indicating circuit of the voltage tester, said piezoelectric device comprising a metallic frame having two terminal support points, two piezoelectric elements having respective ends mounted for pivotal movement about said terminal support points, a metallic terminal member located between their other ends so that the piezoelectric elements form a large obtuse angle, said member for applying the mechanical load being mounted adjacent said metallic terminal member to change said angle.

Claim 3

In a voltage tester of the type comprising one or more contact elements for engaging a conductor to be tested for its voltage condition, an insulated armature for capacitively cooperating with ground, and an indicating circuit including glow discharge means connected between said contact elements and said armature, the improvement which comprises the provision of means for checking the operativeness of said voltage tester comprising a piezoelectric device, a member for applying a mechanical load thereto to produce a voltage between opposed terminals of the piezoelectric device, electrical leads extending from said terminals, and a spark-gap in one of said leads, said leads being arranged for connection across said indicating circuit of the voltage tester, said piezoelectric device comprising a single piezoelectric element having terminals at each end, a spring supported mass, a snap-lock mechanism for restraining said mass, and push-button means for releasing said mass to cause it to contact the piezoelectric element to apply a load thereto.

Claim 4

In a voltage tester of the type comprising one or more contact elements for engaging a conductor to be tested for its voltage condition, an insulated armature for capacitively cooperating with ground, and an indicating circuit including glow discharge means connected between said contact elements and said armature, the improvement which comprises the provision of means for checking the operativeness of said voltage tester comprising a piezoelectric device, a member for applying a mechanical load thereto to produce a voltage between opposed terminals of the piezoelectric device, electrical leads extending from said terminals, and a spark-gap in one of said leads, said leads being arranged for connection across said indicating circuit of the voltage tester, said piezoelectric device comprising a single piezoelectric element having terminals at each end, a spring supported mass, a snap-lock mechanism for restraining said mass, and push-button means for releasing said mass to cause it to contact the piezoelectric element to apply a load thereto.

Claim 5

In a voltage tester of the type comprising one or more contact elements for engaging a conductor to be tested for its voltage condition, an insulated armature for capacitively cooperating with ground, and an indicating circuit including glow discharge means connected between said contact elements and said armature, the improvement which comprises the provision of means for checking the operativeness of said voltage tester comprising a piezoelectric device, a member for applying a mechanical load thereto to produce a voltage between opposed terminals of the piezoelectric device, electrical leads extending from said terminals, and a spark-gap in one of said leads, said leads being arranged for connection across said indicating circuit of the voltage tester, said piezoelectric device, said member for applying a mechanical load, and said sparkgap being located in a housing having an internal conductive armature connected to one of said electric leads, said housing being adapted to be held in one hand of an operator so that when the other hand grasps the voltage tester and engages a contact element thereof with the otheR of said electrical leads, a capacitive connection is made across said indicating circuit through the operator''s body.

Claim 6

In a voltage tester of the type comprising one or more contact elements for engaging a conductor to be tested for its voltage condition, an insulated armature for capacitively cooperating with ground, and an indicating circuit including glow discharge means connected between said contact elements and said armature, the improvement which comprises the provision of means for checking the operativeness of said voltage tester comprising a piezoelectric device, a member for applying a mechanical load thereto to produce a voltage between opposed terminals of the piezoelectric device, electrical leads extending from said terminals, and a spark-gap in one of said leads, said leads being arranged for connection across said indicating circuit of the voltage tester, said piezoelectric device, said member for applying a mechanical load, and said sparkgap being located in a housing having an internal conductive armature connected to one of said electric leads, said housing being adapted to be held in one hand of an operator so that when the other hand grasps the voltage tester and engages a contact element thereof with the otheR of said electrical leads, a capacitive connection is made across said indicating circuit through the operator''s body.