JPH01234035A - Interlayer short-circuit detecting device for field winding - Google Patents

Abstract

PURPOSE:To monitor interlayer short-circuits all the time, by incorporating a pickup coil in a wedge for fixing an armature winding that is inserted in the slot of a stator core, mounting a probe edge having a lead wire, and detecting leaking magnetic flux. CONSTITUTION:An armature winding 8 which is wound in the slot of a stator core 2 is fixed in the slot with a fixing wedge 15. A probe wedge 14 is mounted on the stator wedge 15. A probe 3 incorporating a pickup coil is made to protrude in an air gap 4 from the probe wedge 14. The output of the pickup coil is led out to the outside through a lead wire 12. The probe 3 having the pickup coil is securely fixed. The removal of a rotor 1 in disassembling becomes easy. Thus, leaking magnetic flux is always detected, and interlayer short-circuits are always monitored precisely.

Description

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

(Prior Art) For example, in a turbine generator, field windings are embedded in a plurality of rotor grooves provided in the axial direction on the outer circumferential surface of a cylindrical rotor. The generated 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 groove, electrical and mechanical imbalance will occur due to magnetic and thermal imbalance in the rotor, leading to a generator failure. There is a risk that

There is a method of detecting interlayer short circuits between field winding conductors, which cause such accidents, by detecting changes in the resistance of the field winding.
When considering an interlayer short circuit of the conductor for one out of 114 turns of the field winding, the change in resistance is as small as about 0.9%, and detection is extremely difficult.

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 detection of interlayer short circuits is not based on resistance changes, but is based on the field that caused the interlayer short circuit. By comparing the local leakage magnetic flux on the rotor outer circumferential surface due to the grooved winding in which the magnetic winding conductor is embedded with the leakage magnetic flux due to the field winding that does not cause an interlayer short circuit, it is possible to detect short interlayer terminations. A method is known in which the conductor of the field winding that has been generated is buried in the groove to identify the groove.

In this method, as shown in FIG. 4, a ring-shaped air gap or air gap 4 formed between the rotor 1 and the stator core 2 is filled with the outside of the stator frame. A cylindrical probe 3 made of a non-magnetic material, such as stainless steel or synthetic resin, is provided penetrating the Jl plate 10 and close to the outer peripheral surface of the rotor 1, and a pickup coil is accommodated in the probe 3. There is.

This probe 3 is sealed with the inside of the generator by a probe seat 11 provided on the stator frame outer peripheral plate 10.
It is installed avoiding the armature winding 8 embedded in the stator groove of the stator core 2 and the spacer piece 9 that forms a passage for in-machine cooling gas, and is connected to the voltage display device 13 via the lead wire 12. There is.

Interlayer short circuit is detected by the field winding 6 embedded in the first rotor groove 5.
By interlinking the leakage magnetic flux 7 generated by this with the pickup coil, a voltage with a magnetic flux pulsation frequency determined by the product of the number of rotor grooves 5 and the rotation speed of the rotor 1 is induced in the pickup coil, and this voltage waveform is converted into a voltage. This is done by displaying the information on the display device 13 and identifying the rotor groove in which the field winding conductor is embedded, where the interlayer short circuit has occurred based on the irregularity of the voltage waveform.

(Problem to be solved by the invention) In the detection device as described above, the probe 3 is connected to the rotor 1.
In order to permanently install the probe 3 close to the outer peripheral surface of the rotor, it was necessary to maintain the distance from the outer peripheral surface of the rotor and to withstand wind pressure during rotation, which caused problems in fixing the probe 3. Also, for example, when the inside of a machine such as a turbine generator is cooled with hydrogen gas,
Since the reliability of the hydrogen gas seal at the probe mounting seat 11 is also important, devices for detecting interlayer short circuits have traditionally been installed temporarily rather than permanently.

The present invention eliminates the above-mentioned conventional drawbacks and permanently installs the probe of the field winding interlayer short circuit detection device, and also enables hydrogen gas release, probe setting, and hydrogen gas regeneration even in hydrogen gas cooled turbine generators. It is an object of the present invention to provide a device that can easily and safely detect interlayer short circuits without going through a process such as encapsulation.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, the field winding interlayer short circuit detection device of the present invention includes a probe having a pickup coil built in an air gap, and a probe that fixes the probe. The probe wedge is provided with a wedge and a lead wire connected to the pickup coil, and the probe wedge is attached to the stator wedge that holds the armature winding in the stator core. Further, the lead wire is routed through a through hole provided in the probe model, and the probe is disposed at the axial end position of the air gap.

(Function) Since the present invention is constructed as described above, the probe is firmly fixed to the stator core by the probe wedge and the stator wedge, the position of the probe is always stable within the air gap, and the wind pressure during rotation etc. This prevents the distance from the rotor from becoming unstable.

Furthermore, the process of attaching and detaching one probe and the process of releasing and refilling the internal cooling gas, which were conventionally required each time an interlayer short circuit detection test is performed, are no longer necessary.

Furthermore, by providing the probe at the axial end of the air gap, the probe faces the non-magnetic portion of the rotor, and the waveform of magnetic flux detection becomes clearer.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, the probe 3 with a built-in pickup coil is embedded in a double-tail probe PJj 14, and the probe model 14 is embedded in the inner circumferential groove of the stator core 2 and placed in the upper part that holds the armature winding 8. It is inserted and fixed into a stator mold 15 having a dovetail-shaped groove in the axial direction.

The probe wedge 14 has a lead wire 12 connected to the probe 3.
The lead wire 12 passes through this hole, runs along the end of the internal core of the generator, is pulled out of the machine, and is connected to a voltage display device.

Further, the probe 3 is disposed at the axial end position of the air gap, and the tip thereof is set to face the non-magnetic portion of the rotor wedge.

Further, FIG. 2 shows a cross-sectional view of a main part in a state where the probe 3 is placed in the air gap 4 between the rotor 1 and the stator 2.

In the above configuration, short interlayer termination of the field winding can be detected by interlinking the leakage magnetic flux generated by the field winding embedded in the rotor groove with the pickup coil in the probe 3. This is done by inducing a voltage in the pickup coil with a magnetic flux pulsation frequency determined by the product of the number of threads and the rotation speed of the rotor, and detecting irregularities in this voltage waveform.

In this embodiment, the stator wedge 15 is used to fix the probe 3, so it can be fixed securely, and since the probe 3 is attached at the end of the stator core, there is a gap between the surface of the rotor 1 and the probe 3. can be easily realized, the rotor can be easily pulled out during disassembly, and since it faces the non-magnetic part of the rotor, the leakage flux waveform for detecting interlayer short circuit becomes clear.

Furthermore, since the probe 3 can be mounted at any position on the circumference, there is no restriction on the mounting position to avoid obstacles etc. as in the past.

In addition, the hydrogen gas seal inside the machine for pulling the lead wire out of the generator can use the same packing gland as the lead wire for the temperature measuring element inside the machine, so there is no need to seal it independently at the probe mounting seat like in the past. There is no.

As described above, in this embodiment, the probe 3 is firmly fixed to the stator wedge 15 via the probe wedge 14, and since the mounting position is at the end of the stator core, the mounting state can be monitored.
Since the gap between the probe 3 and the rotor surface can be actually measured, highly reliable detection can be performed.

Further, since the probe 3 can be opposed to the non-magnetic portion of the rotor 1, the leakage magnetic flux waveform becomes clear, and interlayer short circuits can be detected with high accuracy.

Further, since the probe 3 can be attached at any position in the circumferential direction, the work efficiency can be greatly improved by selecting a position where the work can be easily done.

In addition, the position where the detection lead wire 12 is pulled out to the outside of the machine can be shared with the packing gland for pulling out the element lead wires for indoor temperature greenhouses, so the hydrogen gas seal inside the machine can be reduced, and the detection probe can be set at the time of detection. It also eliminates the need for processes such as releasing and re-enclosing hydrogen gas, improving reliability as a generator.

Next, another embodiment of the present invention will be described with reference to FIG. In the figure, the probe wedge 14 has a dovetail-shaped cross section as in the previous embodiment, but the probe wedge 14 is fixed only once.
The probe wedge 14 is inserted and fixed into a groove provided in the stator wedge 15, and the probe wedge 14 is inserted and fixed in a groove provided in the stator wedge 15, and the probe wedge 14 is inserted and fixed in a groove provided in the stator wedge 15. You can get the same effect as . This embodiment is particularly effective when the cross-sectional area of one stator member is small.

〔Effect of the invention〕

As explained above, in the field and line interlayer short circuit detection device of the present invention, the probe is firmly fixed to the stator wedge located at the axial end of the stator core through the probe wedge, so the probe position is fixed. Interlayer short circuit detection can always be performed stably and with high reliability.

Further, since there is no need to remove the probe even during operation, interlayer short circuit detection can be performed at all times. Furthermore, with hydrogen-cooled generators, etc., there is no need to release and re-enclose hydrogen gas inside the machine, which is performed every time an interlayer short circuit detection test is performed, so there is no need to release or re-enclose hydrogen gas, which has a risk of explosion depending on the hydrogen gas concentration. Safety is also greatly improved as this process can be omitted.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing how an interlayer short circuit detection device according to an embodiment of the present invention is installed, and FIG. 2 is a circumferential position of the probe attached and fixed on the inner circumferential surface of the stator core shown in FIG. FIG. 3 is a cross-sectional view of a main part showing how a probe wedge is fixed to a stator model according to another embodiment of the present invention, and FIG. 4 is a diagram showing a conventional field winding interlayer short circuit detection device. It is a schematic diagram showing an attachment situation. 1... Rotor 2... Stator core 3...
・Probe 8...Armature winding 12...Lead wire 14...Probe wedge 15...Stator wedge Agent Patent attorney Nori Chika Ken Yudo Daishimaru Ken Figure 1 Figure 2

Claims (3)

[Claims] (1) The probe is provided in the air gap of a rotating electrical machine and includes a probe with a built-in pickup coil, a probe wedge that fixes the probe, and a lead wire connected to the pickup coil, and the probe wedge is fixed. An interlayer short circuit detection device for a field winding, characterized in that it is attached to a stator wedge that holds an armature winding in a child core. (2) The interlayer short circuit detection device for a field winding according to claim 1, wherein the lead wire is routed through the through hole of the probe wedge. (3) The interlayer short circuit detection device for a field winding according to claim 1, wherein the probe is provided at an axial end position of the air gap.