Method and apparatus for diagnosing bearing insulation impedance of a rotating electrical apparatus
First Claim
1. A system for diagnosing operability of a rotating electrical apparatus including a rotatable shaft having a voltage, a stator, bearing means and an insulator, with the bearing means electrically contacting the rotatable shaft and the insulator at least partially electrically insulating the rotatable shaft and the bearing means from the stator, said system comprising:
- means for inducing an electrical signal, which is different than said voltage of said rotatable shaft, in said rotatable shaft;
variable impedance means in parallel with said insulator, said variable impedance means having a first impedance and a second impedance;
means for sensing a first electrical parameter associated with said first impedance and a second electrical parameter associated with said second impedance; and
means for determining the operability of said insulator from the first and second electrical parameters and the second impedance.
2 Assignments
0 Petitions
Accused Products
Abstract
A system diagnoses the operability of a rotating electrical apparatus such as a reactor coolant pump (RCP) motor. The RCP motor includes a rotatable shaft, a stator, a bearing assembly and a bearing insulator. The bearing assembly electrically contacts the rotatable shaft and the bearing insulator at least partially electrically insulates the rotatable shaft and the bearing assembly from the stator. The system includes a shaft transformer and voltage source for inducing a voltage in the rotatable shaft; a variable resistor in parallel with the bearing insulator having first and second resistances; an analog-to-digital converter for sensing a first voltage associated with the first resistance and a second voltage associated with the second resistance; and means for determining the operability or the impedance of the bearing insulator from the first and second voltages and the second resistance.
19 Citations
20 Claims
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1. A system for diagnosing operability of a rotating electrical apparatus including a rotatable shaft having a voltage, a stator, bearing means and an insulator, with the bearing means electrically contacting the rotatable shaft and the insulator at least partially electrically insulating the rotatable shaft and the bearing means from the stator, said system comprising:
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means for inducing an electrical signal, which is different than said voltage of said rotatable shaft, in said rotatable shaft; variable impedance means in parallel with said insulator, said variable impedance means having a first impedance and a second impedance; means for sensing a first electrical parameter associated with said first impedance and a second electrical parameter associated with said second impedance; and means for determining the operability of said insulator from the first and second electrical parameters and the second impedance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for diagnosing operability of a rotating electrical apparatus including a rotatable shaft having a voltage, a stator, first bearing means, second bearing means, a first insulator and a second insulator, with the first and second bearing means electrically contacting the rotatable shaft, and with each of the first and second insulators at least partially electrically insulating the rotatable shaft and a corresponding one of the first and second bearing means from the stator, said system comprising:
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means for inducing an electrical signal, which is different than said voltage of said rotatable shaft, in said rotatable shaft; variable impedance means in parallel with one of said insulators, said variable impedance means having a first impedance and a second impedance; means for sensing a first electrical parameter associated with said first impedance and a second electrical parameter associated with said second impedance; and means for determining the operability of at least one of said insulators from the first and second electrical parameters and the second impedance. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A system for diagnosing operability of a rotating electrical apparatus including a rotatable shaft having a voltage, a stator, bearing means and an insulator having an impedance, with the bearing means electrically contacting the rotatable shaft and the insulator at least partially electrically insulating the rotatable shaft and the bearing means from the stator, said system comprising:
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means for inducing an electrical signal, which is different than said voltage of said rotatable shaft, in said rotatable shaft; variable impedance means in parallel with said insulator, said variable impedance means having a first impedance and a second impedance; means for sensing a first electrical parameter associated with said first impedance and a second electrical parameter associated with said second impedance; and means for determining the impedance of said insulator from the first and second electrical parameters and the second impedance.
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19. A method for diagnosing operability of a rotating electrical apparatus including a rotatable shaft having a voltage, a stator, bearing means and an insulator having an impedance, with the bearing means electrically contacting the rotatable shaft and the insulator at least partially electrically insulating the rotatable shaft and the bearing means from the stator, said method comprising the steps of:
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inducing an electrical signal, which is different than said voltage of said rotatable shaft, in said rotatable shaft; employing a first impedance in parallel with said insulator; sensing a first electrical parameter associated with said first impedance; employing a second impedance in parallel with said insulator; sensing a second electrical parameter associated with said second impedance; and determining the impedance of said insulator from the first and second electrical parameters and the second impedance. - View Dependent Claims (20)
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Specification