Fault diagnosis system for rotor winding of rotary electric machine

• US 4,851,766 A
• Filed: 12/09/1987
• Issued: 07/25/1989
• Est. Priority Date: 12/15/1986
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shiobara, Ryoichi, Ohi, Masao
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Nguyen, Vinh P.
• Application Number:
  US07/130,477
• Time in Patent Office: 594 Days
• Field of Search: 324/158 MG, 324/55, 324/62, 324/430, 324/546, 324/547, 340/648, 318/490, 318/696, 363/71, 322/99
• US Class Current: 324/765.01
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: G01R 31/346 Testing of armature or field windings

Abstract

A fault diagnosis system for a rotor winding of rotary electric machines is disclosed, in which the rotor winding of rotary field type is excited in DC fashion by an excitation circuit, on which an AC voltage is superposed, the impedance of the rotor winding is calculated from the current and voltage of the AC portion flowing in the rotor winding, and the resulting impedance is compared with a reference impedance thereby to decide a fault, if any, of the rotor winding, thus making possible accurate diagnosis of a rotary electric machine even while it is running.

Claims

1. A fault diagnosis system for a rotor winding of a rotary electric machine, comprising a rotor winding of rotary field type, DC excitation means for exciting the rotor winding, a power supply for superposing an AC voltage on the DC voltage of the excitation means, a field voltage detector for detecting the AC portion of the voltage of the rotor winding, a field current detector for detecting the AC portion of the current flowing in the rotor winding, an arithmetic unit for calculating the impedance of the rotor winding from the current and voltage detected by the field current detector and the field voltage detector respectively, and fault decision means for deciding a fault of the rotor winding from the impedance calculated by the arithmetic unit.

2. A fault diagnosis system for a rotor winding of a rotary electric machine, comprising a field winding, DC excitation means for exciting the field winding, an AC power supply for superposing an AC voltage of the DC voltage of the DC excitation means, a field voltage detector for detecting the voltage value of the AC portion of the rotor winding, a field current detector for detecting the current value of the AC portion of the rotor winding, an arithmetic unit for calculating the impedance of the field winding from the values detected by the field current detector and the field voltage detector, and a comparator for comparing the impedance calculated by the arithmetic unit with a reference impedance prepared in advance, wherein the magnitude of the difference of the impedances produced by the comparator is used to decide a fault of the field winding.

3. A fault diagnosis system according to claim 2, wherein said reference impedance takes a value calculated by the arithmetic unit a predetermined period of time in advance.

4. A fault diagnosis system for a rotor winding of a rotary electric machine, comprising a rotor winding of rotary field type, DC excitation means for exciting the rotor winding, a power supply for superposing an AC voltage on the DC voltage of the excitation means, a field voltage detector for detecting thr AC portion of the voltage of the rotor winding, and a field current detector for detecting the AC portion of the current flowing in the rotor winding, means for calculating the impedance of the rotor winding from the voltage value of the field voltage detector and the current value of the field current detector, and comparator means for comparing the impedance thus calculated with a reference impedance, so that the magnitude of the difference between said impedance and said reference impedance is used to decide a fault of the rotor winding.

5. A fault diagnosis system for a rotor winding of a rotary electric machine, comprising a rotor winding of rotary field type, DC excitation means for exciting the rotor winding, a power supply for superposing an AC voltage on the DC voltage of the excitation means, a field voltage detector for detecting the AC portion of the voltage of the rotor winding, a field current detector for detecting the AC portion of the current flowing in the rotor winding, an arithmetic unit for calculating the impedance of the rotor winding from the current and voltage detected by the field current detector and the field voltage detector respectively, and fault decision means for deciding a fault of the rotor winding from the impedance calculated by the arithmetic unit, wherein said fault decision means includes a reference signal generator for producing the reference impedance and a comparator for comparing the impedance calculated by the arithmetic unit the reference impedance produced from the reference signal generator and an alarm for producing an alarm signal when the difference between the impedance and the reference impedance exceeds a predetermined value.

6. A fault diagnosis system for a rotor winding of a rotary electric machine, comprising a rotor winding of rotary field type, a DC excitation circuit connected to the rotor winding for exciting the same, AC-AC superposing means for superposing an alternating current on the direct current of the DC excitation circuit, an AC power supply circuit for supplying an alternating current to the DC-AC superposing means associated with said DC excitation circuit, a field voltage detector for detecting the superposed AC portion of the voltage produced from the DC excitation circuit, a field current associated with said DC excitation circuit for detecting the superposed AC portion of the current of the DC excitation circuit, an arithmetic unit for calculating the impedance of the rotor winding from the values detected by the field current detector and the field voltage detector, a comparator for comparing the impedance calculated by the arithmetic unit with a predetermined reference impedance, and alarm means for producing a predetermined alarm signal when the difference between the impedance and the reference impedance produced from the comparator exceeds a predetermined value.