JPH01298928A - Layer short detector for field winding - Google Patents

Abstract

PURPOSE:To eliminate the removal of a detecting probe at the time of removal and insertion of a rotor by rotatably mounting the probe. CONSTITUTION:A probe 3 is secured to a probe guide 16, and rotatably mounted in a probe wedge 14. It is pressed by a helical spring 22 fixedly in a probe position securing groove 18 at its measuring position, and directed toward the center of a rotor. The guide 16 is pressed at the time of removal and insertion of the rotor, the probe 3 is removed from the securing groove 18 against the spring 22, rotated at 90 deg., and secured toward the circumferential direction of the rotor. It does not disturb the removal and insertion of the rotor at this position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a device for detecting an interlayer short circuit in a field winding provided in an air gap of a rotating electric machine.

(Prior art) For example, in a turbine generator, a field winding is embedded in a plurality of grooves provided on the outer peripheral surface and axial direction of a cylindrical rotor, and the field is generated by the rotor. The magnetic flux induces a commercial frequency voltage in the armature winding embedded in the stator core.

In the unlikely event that an interlayer short circuit occurs between the field winding conductors embedded in the rotor grooves, magnetic and thermal imbalance will occur in the rotor.
There is a risk that the vibration imbalance will lead to a generator accident.

In order to detect an interlayer short circuit between the field winding conductors, which causes such an accident, by a change in resistance of the field winding, for example, assuming that the number of turns of the field winding is 114, it is necessary to The resistance change due to the interlayer short circuit of the conductor was as small as 0.9%, and it was extremely difficult to detect.

In addition, interlayer short circuits occur when centrifugal force due to high-speed rotation of the rotor and force due to temperature rise during operation act, so conventionally, interlayer short circuits were detected without relying on resistance changes. Detects the difference between the locally decreased magnetic flux on the rotor outer circumferential surface caused by the grooved winding in which the field winding conductor is embedded, and the leakage magnetic flux caused by the field winding that has not caused the interlayer short circuit. A method is known in which the field winding conductor in which the interlayer short circuit has occurred is buried and the groove can be identified with high sensitivity.

In this method, as shown in FIG. 6, a non-magnetic material 1 is provided close to the outer peripheral surface of the rotor 1 in a ring-shaped air gap formed between the rotor 1 and the stator core 2. For example, a cylindrical probe 3 made of stainless steel or synthetic resin
The number of customers in the rotor groove 5 and the rotation speed of the rotor can be changed by intersecting the leakage magnetic flux 7 generated by the field winding 6 embedded in the groove 5 of the rotor with the pickup coil 4. A voltage with a magnetic flux pulsation frequency determined by the product of the oscillation frequency and the oscillation frequency is induced in the pickup coil 4, and the groove in which the field winding conductor is buried, where the interlayer short circuit has occurred, is identified from the irregularity of this voltage waveform.

In Fig. 7, 8 is the armature winding embedded in the groove of the stator core 2, 15 is the stator pole for fixing the armature winding, and the second
In the figure, 14 is a probe wedge with a built-in probe 3 and a dovetail cross-sectional shape that allows the stator pole 15 to slide in the axial direction of the air gap, and 12 is a probe wedge provided outside the generator to transfer the voltage induced in the pickup coil 4. This is a lead wire leading to the display device 13.

(Problem to be Solved by the Invention) In the detection device as described above, the probe 3 protrudes toward the center of the rotor from the outer diameter surface of the retaining ring that holds the end of the core of the field winding 6. It is necessary to fix it close to the
This caused an obstruction when removing or reinserting the rotor from inside the stator. Therefore, when the rotor is pulled out and reinserted, the probe 3
It was necessary to slide the dovetail cross section of the probe wedge 14 and the stator pole 15 into the air gear shaft to remove them from the stator pole.

This invention eliminates the drawbacks of the conventional method described above and moves the probe of the field winding short interlayer detection device to the outer circumferential side of the rotor retaining ring so as not to become an obstacle when the rotor is pulled out and reinserted. The purpose is to provide a device that facilitates maintenance and fixation.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a device for detecting an interlayer short circuit that occurs in a field winding embedded in a rotor groove of a rotating electrical machine. A probe with a built-in pickup coil is installed close to the circumferential surface of the rotor in the air gap formed between the probe and the armature winding embedded in the inner circumferential groove of the stator core that fixes this probe. A probe guide round hole that can easily slide in the air gap axial direction on the stator pole that holds the rotor, and a semicircular probe position fixing groove that fixes the probe in the air gap axial direction and circumferential direction toward the rotor center. The rotor can be pulled out and re-inserted without removing the probe from the stator pole by incorporating a built-in spring that securely fixes the probe and allows the probe guide to easily slide in the axial direction. It is characterized by the fact that

(Function) The present invention is configured as described above, and when detecting an interlayer short circuit, the tip of the probe, that is, the detection part is fixed so as to face the rotor center direction, and when one rotor is pulled out or inserted, one rotor is Since it is fixed so that it faces in the circumferential direction (tangential direction) of the rotor, there is no need to pull out and insert the rotor, and it also prevents damage to the probe and breakage of the lead wire, ensuring reliability in detecting interlayer short circuits. It also improves.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows one embodiment of the present invention, and shows an overall view of a probe wedge 14 in which a probe is built into a stator wedge that holds an armature winding at the end of a stator core.

FIG. 2 shows a cross section of the probe wedge 14 shown in FIG. 1, showing a state in which the probe 3 is fixed and facing toward the center of the rotor. FIG. 3 shows a cross section of the probe wedge 14 shown in FIG. 1, showing a state in which the probe 3 is oriented and fixed in the circumferential direction of the air gap. Figure 4 shows the probe guide 1 shown in Figures 1 to 3.
6 shows a cross section of a lock nut incorporating a lock spring 21 that fits into a lock groove 19 provided in the nut 6. Figure 5 shows the helical coil spring 2 built into the probe wedge 14.
2 is shown.

Next, the operation of this embodiment will be explained. That is, the field winding interlayer short termination detection device configured as described above operates as follows.

(υ Since the probe 3 is attached to the probe wedge 14 which also serves as a stator wedge provided at the end of the stator core, the probe 3 can be fixed securely and firmly.

- Since the probe 3 is installed at the end of the stator core, the gap from the surface of the stator 1 to the probe 3 can be measured and adjusted easily.

(2) By sliding the probe guide 16 in the axial direction, the direction of the probe 3 can be changed to the rotor center direction or the air gap circumferential direction.

0) When the probe guide 16 is slid in the axial direction, it can be easily slid by the force of the spring built into the probe wedge 14.

(2) In addition to being fixed by the force of a spring, the probe position fixing groove 18 provided in the probe wedge 14 allows for reliable fixation.

■ By simply moving the lock nut provided at the end of the probe wedge 14 along the probe guide 16 in the axial direction, the spring 21 built into the lock nut 20 engages the lock groove 19 provided in the probe guide 16 to lock the probe 3 in the direction 1. The position can be reliably fixed in the rotor center direction or air gap circumferential direction.

■ By using a helical coil in the spring 22 built into the probe wedge 14 and fixing one end of the spring to the probe wedge or the other end to the probe guide 16, the direction of the probe 3 is controlled by the repulsive force in the winding direction of the helical coil. can be easily changed toward the rotor center direction or the air gap circumferential direction.

(8) Since the direction of the probe 3 can be changed in the circumferential direction of the air gap, the rotor coil retaining ring, which is larger than the outer diameter of the rotor core, does not come into contact with the probe 3 when the rotor is inserted or disassembled. Therefore, the probe mounting location can be selected arbitrarily in the circumferential direction of the air gap.

Next, the effects of this embodiment will be described below.6 (1) Since the probe 3 is installed at the end of the stator core, the installation status can be visually confirmed, and the gap between the rotor surface and the probe can be actually measured. Since the adjustment is easy, a highly reliable waveform can be obtained.

■ Since the rotor + ff16 mounts the probe 3 horizontally on a non-magnetic material, the built-in probe guide 16 including the probe wedge 14, lock nut 20, spring 22, etc. are made of non-magnetic materials such as stainless steel or synthetic resin to prevent leakage. The magnetic flux waveform becomes clearer, and a more accurate interlayer short circuit detection device can be provided.

■ Probe 3 connects probe guide 16 to probe wedge 14
The direction of the probe wedge 14 can be changed by sliding it in the axial direction inside the probe wedge 14 when inserting or removing the rotor.
There is no need to disassemble the probe, which improves the reliability of probe installation.

) Since the probe can be installed at any position in the circumferential direction of the air gap, reliability and
will improve.

■ Since the direction of the probe 3 can be changed inside the probe stem 14 to detect interlayer short circuits in the field winding as shown in Figure 1, the probe wedge can be disassembled when the rotor is inserted or removed after the probe is installed. There is no longer a need to do this, making recovery easier, and not only can the generator be operated continuously, but it has also become easier to test the field winding for interlayer short circuit detection.

〔Effect of the invention〕

As explained above, in the field winding interlayer short circuit detection device of the present invention, the probe is fixed at the stator wedge located at the axial end of the inner circumference of the stator core, and the probe is attached to the stator wedge itself. As a result, the structure is simple, the probe mounting part is securely fixed, and it is now possible to check both visually and by touch.

Furthermore, in the conventional method of inserting and fixing a dovetail-shaped probe wedge with a built-in probe into the stator wedge at the end of the iron core, the probe protrudes toward the center of the rotor when the rotor is inserted or removed from the stator. The retaining ring that holds the field winding end, which has a diameter larger than the outer diameter of the rotor core, became an obstacle and the probe wedge had to be disassembled each time.However, with the present invention, the rotor can be removed without disassembling the probe wedge. Since it is now possible to insert and pull out the probe, the reliability of fixing the probe during disassembly and reassembly of the probe wedge is further improved, and the probe can be used to detect short circuits between the field winding layers during continuous operation of the generator. This eliminates the possibility of being unable to test due to a problem with the mounting part. Therefore, for example, in a generator with internal hydrogen gas cooling,
It is possible to omit the process of releasing and re-inserting the hydrogen gas inside the machine, which has a risk of explosion depending on the hydrogen gas concentration, and has the great effect of omitting the process of disassembling and reassembling the probe wedge. It is something that you have.

[Brief explanation of the drawing]

Fig. 1 is a detailed view of an embodiment of the probe mounting part according to the present invention, Fig. 2 is a sectional view of the embodiment when the probe is oriented toward the rotor center, and Fig. 3 is a sectional view of the embodiment when the probe is oriented toward the circumferential direction of the air gap. FIG. 4 is a cross-sectional view of a lock nut that locks the probe guide, FIG. 5 is a cross-sectional view of a spring built into the probe wedge, and FIG.
The figure shows the overall structure of a probe for detecting a short circuit between the field winding layers installed in the air gap of a rotating electrical machine, and FIG. 7 is a detailed view of a conventional probe mounting part. 1... Rotor, 2... Stator core, 3...
...Probe, 4...Pickup coil 5.
... Rotor groove, 6... Field winding, 7... Leakage flux, 8... Armature winding. 10... Stator frame outer peripheral plate, 12... Lead wire, 13... Voltage display device. 14... Probe wedge, 15... Stator wedge, 16
...Rotor wedge, 17...Probe guide hole,
18... Probe position fixing groove, 19... Lock groove, 20... Lock nut, 21... Lock nut spring, 22... Helical coil spring. Agent Patent Attorney Noriyuki Chika Ken Yudo Daishimaru Ken Figure 4

Claims (3)

[Claims] (1) In a device that detects an interlayer short circuit in a field winding embedded in a rotor groove of a rotating electric machine, a ring-shaped air gap (hereinafter referred to as an air gap) formed between a stator and a rotor is used. A probe that is provided close to the outer peripheral surface of the rotor and has a built-in pickup coil, a probe guide that fixes the probe, a probe guide round hole that moves this probe guide in the air gap axial direction, and this probe guide round A fixing device in which a spring inserted into a hole and a semicircular probe position fixing groove that fixes the probe in position in the rotor center direction, air gap axial direction, and circumferential direction are embedded in a stator core inner circumferential groove. An interlayer short circuit detection device for a field winding, characterized in that it is provided on a stator wedge that holds a child winding. (2) An interlayer short-circuit detection device for a field winding, characterized in that the probe guide is provided with a locking groove for positioning and fixing the probe in the rotor center direction and rotor circumferential direction. (3) The interlayer short-circuit detection device for a field winding according to claim 2, further comprising a lock nut having a built-in lock spring that fits into a lock groove of the probe guide.