TEMPERATURE MEASURING SYSTEM FOR ROTATING MACHINES

• US 3,824,857 A
• Filed: 08/07/1972
• Issued: 07/23/1974
• Est. Priority Date: 08/07/1972
• Status: Expired due to Term

• Current Assignee: Dresser-Rand Company Corning New York A General Partnership of New York
• Original Assignee: Forest D. Smith
• Inventors: Smith, Forest D.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Corr, Denis E.
• Application Number:
  US05/278,578
• Time in Patent Office: 715 Days
• Field of Search: 73/351,361 340/27R,195,208,227R
• US Class Current: 374/154
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 13/08 in rotary movement

Abstract

A temperature measuring system for measuring the rotor temperature of an electric motor or generator. A temperature signal from a thermocouple mounted on the rotor is amplified and used to run a voltage to frequency converter which generates a signal having a frequency proportional to the temperature. This signal is coupled from the rotating portion to the stationary portion of the machine where it is converted to an analog voltage proportional to the rotor temperature. In one embodiment a rotary transformer is used to couple the signal from the rotating portion to the stationary portion of the machine, while in another embodiment an FM transmitter and receiver is used for the signal coupling.

Claims

1. A temperature monitoring system for monitoring the rotor temperature of a machine having a rotation portion and a stationary portion, said system being independent of axial movements of the rotor shaft, comprising:

a. temperature sensing means associated with the rotating portion for producing a temperature signal indicative of the temperature of the rotating portion;

b. signal conversion means associated with the rotating portion and connected to receive the temperature signal from the temperature sensing means, the signal conversion means operable to produce an intermediate signal having a frequency indicative of the value of the temperature signal;

c. signal coupling means associated with the rotating portion and the stationary portion of the machine and connected to receive the intermediate signal, the signal coupling means operable to convey the intermediate signal from the rotating portion to the stationary portion of the machine; and

d. output means associated with the stationary portion of the machine and connected to receive the intermediate signal from the signal coupling means, the output means responsive only to the frequency of the intermediate signal and operable to produce output signals indicative of the temperature of the rotating portion, whereby the output signals are not affected by axial movements of the rotor.

2. A temperature measuring system for a machine having rotating portion and a stationary portion, for measuring the temperature of the rotating portion independently of any axial movement of the rotation portion, comprising:

a. temperature sensing means attached for rotation with the rotating portion for producing a temperature signal having a voltage indicative of the temperature of the rotating portion;

b. voltage to frequency conversion means attached for rotation with the rotating poRtion and connected to receive the temperature signal from the temperature sensing means, the voltage to frequency conversion means, the signal coupling means being operable to convey the intermediate signal from the rotating portion to the stationary portion of the machine; and

d. frequency to voltage conversion means associated with the stationary portion of the machine and connected to receive the intermediate signal from the signal coupling means, the frequency to voltage conversion means being operable in response to the frequency of the intermediate signal to produce an output voltage indicative of the temperature of the rotating portion of the machine, whereby the output voltage is not affected by amplitude changes in the intermediate signal caused by axial movements of rotating portion of the machine.

3. The apparatus according to claim 2 wherein the temperature sensing means comprises a thermocouple.

4. The apparatus according to claim 3 wherein the temperature sensing means further comprises:

a. a DC amplifier having input means and having an output connected to the voltage to frequency conversion means;

b. temperature compensation resistance means; and

c. means for connecting the thermocouple and the temperature compensation resistance means to the input means of the DC amplifier, so that the temperature signal produced is compensated for changes in ambient temperature.

5. The apparatus according to claim 2 further including level detection means connected to receive the output voltage, the level detection means operable to produce a first out of tolerance signal when the output voltage reaches a value corresponding to a predetermined maximum allowable rotor temperature, and a second out of tolerance signal when the output voltage reaches a value corresponding to a predetermined minimum expected rotor temperature.

6. The apparatus according to claim 2 further including:

a. a power rotary transformer having a primary associated with the stationary portion of the machine, and a secondary associated with the rotating portion of the machine;

b. an AC power supply connected to the primary; and

c. rectification means connected to the secondary for receiving AC power, and connected to the voltage to frequency conversion means and the signal coupling means for supplying DC power thereto.

7. The apparatus according to claim 2 wherein the signal coupling means comprises:

a. frequency modulation transmitting means associated with the rotating portion of the machine and connected to receive the intermediate signal, the frequency modulation transmitting means being operable to transmit a carrier signal modulated by the intermediate signal; and

b. frequency modulation receiving means associated with the stationary portion of the machine and connected to the frequency to voltage conversion means, the frequency modulation receiving means being operable to receive the transmitted carrier signals and to demodulate and deliver the intermediate signal to the frequency to voltage conversion means.

8. The apparatus according to claim 2 wherein the signal coupling means comprises a signal rotary transformer having a primary associated with the rotating portion of a machine and connected to receive the intermediate signal of the voltage to frequency conversion means, and having a secondary associated with the stationary portion of the machine and connected to convey the intermediate signal to the frequency to voltage conversion means.