Failed fuse detector and detecting method for rotating electrical equipment

• US 4,635,044 A
• Filed: 10/16/1980
• Issued: 01/06/1987
• Est. Priority Date: 10/16/1980
• Status: Expired due to Term

• Current Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Original Assignee: Westinghouse Electric Company LLC (Brookfield Asset Management Incorporated)
• Inventors: South, William H.
• Primary Examiner(s): Rowland, James L.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US06/197,732
• Time in Patent Office: 2,273 Days
• Field of Search: 340/638, 340/639, 340/645, 310/68 R, 310/68 B, 310/68 D, 361/104, 363/50, 363/52, 363/53
• US Class Current: 340/638
• CPC Class Codes: H02H 3/046 Signalling the blowing of a fuse detecting non functioning of a lamp H05B47/20
• CPC Class Codes: H02H 7/065 against excitation faults
• CPC Class Codes: H02K 11/042 Rectifiers associated with rotating parts, e.g. rotor cores or rotary shafts

Abstract

A method and an arrangement of apparatus is provided for remotely detecting the existence of a failed fuse of a brushless exciter rotor'"'"'s rotating rectifier assembly. A conducting fuse produces a magnetic field which is sensed by elements on a stationary structure. A signal corresponding to the conducting status of each fuse is synchronized to the rotational speed of the brushless exciter rotor by means of a preselected oscillator frequency and the status of each individual fuse is retained and displayed until the next inspection of that fuse. Alarm circuitry enables automatic detection of a failed fuse and shutdown in the event of multiple fuse failures. Since this method looks for the instance of current through each fuse, it operates in a fail-safe manner.

Claims

1. A brushless exciter with a failed fuse detector, comprising:

a rotating member of said brushless exciter;

a plurality of diodes fixed to said rotating member and arranged in a manner which rectifies alternating current and produces a direct current field for excitation of a turbine generator;

a plurality of fuses fixed to said rotating member and connected individually in series with each of said diodes;

a plurality of fixed current sensing means disposed about the circumference of said rotating member proximate to the circular path of said fuses during rotation of the rotating member; and

means for synchronizing the use of the current sensing means with the rotation of the rotating member to enable the selective determination of the conducting status of each of said fuses, said synchronizing means comprising means for measuring the instantaneous angular displacement of the rotating member and relating that displacement to a reference position of said rotating member.

2. Apparatus for selectively determining the conducting status of a plurality of conductors which are rigidly attached to the circumference of a rotating device, comprising:

a stationary mark sensing means for remotely sensing a mark on the rotating device and producing a synchronizing signal when the mark proximately passes the mark sensing means;

an angle position oscillating means for producing output pulses at a preselectable frequency;

an angle counting means, whose inputs are the binary synchronizing signal and the output pulses of the angle position oscillating means, for producing an output which is a number representing the accumulated number of output pulses from the angle position oscillating means that have occurred since the most recent synchronizing signal, whereby said output number is a measurement of actual angular displacement of said rotating device relative to the angular position where said mark is proximate to said stationary mark sensing means;

a plurality of current sensing means for remotely sensing an electric current flow in a conductor passing proximate to said current sensing means and producing a binary signal indicative of the conducting status of the conductor, said current sensing means being disposed about the circumference of the rotating device;

a conductor oscillating means for producing output pulses at a preselectable frequency;

a conductor counting means, whose input is the output of the conductor oscillating means, for cyclically incrementing a conductor counter from unity to a value equal to the number of said conductors whose conducting status are to be sensed and whose output is a number equal to the value of said conductor counter;

an angle decoding means, whose input is the conductor number that is the output of the conductor counting means, for determining according to a predetermined scheme the proper angular displacement of said rotating device for sensing the conducting status of the conductor represented by the conductor number, the output of said angle decoding means being a number representative of the proper angular displacement;

a comparator means for comparing two inputs, the actual angular displacement of the rotating device and the proper angular displacement for sensing the conducting status of the conductor represented by the conductor number, and producing an enabling signal when the two inputs are identical;

a sense coil decoding means, whose input is the conductor number output of the conductor counting means, for determining the proper one of the plurality of current sensing means for sensing the conducting status of the conductor represented by the conductor number, based upon a predetermined scheme, and producing an output which is a number representing the proper one of the plurality of current sensing means;

a current sense coil selecting means, whose inputs are the enabling signal and the output number produced by the sense coil decoding means, for producing an output signal equivalent to the output from the current sensing means represented by the output from the sense coil decoding means when the enabling signal from the comparator indicated an equality between the actual angular displacement and the proper angular displacement for sensing the conducting status of the conductor represented by the conductor number;

a conductor status indicator decoding means, whose input is the conductor number, for producing an output which is a number representing the physical location of the conductor on the rotating device represented by the conductor number;

a conductor status indicator selecting means, whose inputs are the output number from the conductor status indicator decoding means and the conducting status output from the current sense coil selecting means, for retaining the most recent conducting status for each of the plurality of conductors and producing an output representing the conducting status of each of said conductors; and

a displaying means for visually indicating the most recent conducting status of each of the plurality of conductors as received as an input from the output of the conductor status indicator decoding means.

3. The rotating device with apparatus of claim 2, wherein:

said current sensing means comprises a device that reacts to the magnetic field created by an electric current and produces a signal proportionate to said electric current.

4. A method for selectively determining the conducting capability status of a plurality of conductors which are rigidly attached to the circumference of a rotating device, said method comprising:

marking a location on said rotating device in such a way that the marked location is able to be detected remotely;

detecting said mark remotely on each revolution of the rotating device when said mark passes a fixed point;

remotely sensing the conducting status of said conductors;

sequentially determining the identity of the one of the plurality of conductors to be monitored during each subsequent revolution of said rotating device;

measuring the incremental angular displacement of the rotating device that has occurred since the most recent detection of the mark on the rotating device;

selecting the one of plurality of sensing means which is a proper position to determine the conducting status of said conductor;

activating the chosen sensing means when said conductor is proximate said sensing means;

synchronizing the rotation of the rotating device with the determining of the conductor and the selecting of the sensory means; and

visually displaying the most recent conducting status of each of said conductors.

5. The method of claim 4, further comprising:

activating an alarm when one of said conductors has been sensed to have a nonconducting status.

6. The method of claim 4, further comprising:

shutting down said rotating device when a plurality of conductors have been sensed to have a nonconducting status.

7. The method of claim 4, further comprising:

automatically adjusting the sensitivity of the current sensors so that their sensitivity level varies inversely with the expected current flow through said conductors to minimize interference from conductors adjacent to the selected conductor.