Apparatus for monitoring rotary machines
An encoder for use with a machine includes at least one moveable member. The encoder also includes at least one sensor configured to activate via magnetic flux and is configured to dissipate electrical signals with a power amplitude less than approximately one microwatt.
1. An encoder for use with a machine including at least one moveable member, said encoder comprising at least one sensor configured to activate via magnetic flux, said at least one sensor comprises a plurality of switches coupled together in parallel, said switches configured to substantially prevent current flow through said encoder when said switches are open, and to have a substantially zero voltage across said switches when said switches are closed such that said encoder is configured to dissipate less than approximately one microwatt of power.
2. An encoder in accordance with claim 1 wherein each of said switches is configured to dissipate less than approximately one-third of one microwatt of power.
3. An encoder in accordance with claim 1 wherein the machine is a rotary machine and the moveable member is a rotatable member, said encoder further comprising:
at least one rotor configured to rotatably couple to the rotary machine at least one rotating member;
a sealed housing extending over at least a portion of said at least one rotor such that a clearance gap is defined between said housing and said rotor; and
a plurality of magnets coupled within at least a portion of said at least one rotor.
4. An encoder in accordance with claim 3 wherein said plurality of magnets are configured such that said plurality of magnets are spaced circumferentially substantially equidistantly from each other, about said at least one rotor, and a radially outermost portion of each of said plurality of magnets is substantially flush with an outer surface of said rotor.
5. An encoder in accordance with claim 3 wherein said at least one sensor is coupled to said housing and configured to receive magnetic flux from said plurality of magnets.
6. An encoder in accordance with claim 5 wherein said plurality of magnets control the operation of said at least one magnetically-powered sensor.
7. An encoder in accordance with claim 5 wherein said at least one sensor and said plurality of magnets are configured to generate a signal indicative of at least one of a direction of rotation of said rotor and a number of rotations of said rotor.