JPH01190234A - Non-contact type field ground fault detection device - Google Patents

Abstract

PURPOSE:To simplify a construction and to improve a ground fault detection performance by loading a power and signal rotary transformer into a brushless synchronous machine and supplying AC power from a primary side fixing section of the power rotary transformer. CONSTITUTION:When a ground fault comes to a field circuit 2a of a synchronous machine, a power rotary transformer 6 is the power supply, and the ground fault current flows through limiting resistance 8 and a primary side rotating section of a signal rotary transformer 4. Accordingly, a voltage signal generates in a secondary side fixing section of the signal rotary transformer 4. The ground fault of the field circuit can be detected with non-contact by a ground fault detector 5 discriminating a level thereof. The field circuit and a detection device in the case of a ground fault can be protected by the limiting resistance 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to field circuit ground fault detection of a brushless synchronous machine, and particularly relates to a device suitable for non-contact field circuit ground fault detection. .

[Conventional technology]

Conventionally, contact type detection using slip rings and brushes has been widely used to detect field ground faults in synchronous machines, but maintenance and inspection around the brushes has become a major burden. on the other hand,
A contact-type field ground fault detection device for a brushless synchronous machine intended to be maintenance-free has a problem in that it impairs the function of the brushless machine.

Therefore, a non-contact type field ground fault detection device was published in Japanese Patent Application Laid-Open No. 61-19 as "Instruction Manual for Rotor Coil Ground Fault Detection Monitor".
It is disclosed in Publication No. 7155.

The "Rotor Coil Ground Fault Detection Monitor" uses a power supply rotating transformer to supply AC power from a fixed part to the rotating part without contact, and then rectifies it with a detection module in the rotating part to connect the DC power to the rotor coil and the ground. In addition, if a ground fault occurs, the ground fault current is detected by a comparator in the detection module, the thyristor switch is turned on, and the fixed part relay is operated via the output transformer. This method consists of multiple rotating transformers, detection modules, and relays, and is non-contact. However, since the detection module consisting of electronic components is installed in the rotating part, there are reliability problems and the structure is complicated. be.

Furthermore, in Japanese Patent Application Laid-Open No. 61-197155, power is supplied from a fixed part in a non-contact manner using a power supply rotating transformer,
Furthermore, DC power is applied between the field circuit and the ground through a rectifier circuit, and in the event of a ground fault, the primary current and primary impedance of the power supply rotating transformer will change. to detect ground faults. This method has a simple structure because it consists of a power supply rotating transformer, a detector, and a rectifier circuit, but the accuracy of ground fault detection is determined by the performance of the power supply rotating transformer.
When the ground fault detection resistance is high, the ground fault current is small, so the negative side current and impedance change are also small, making it difficult to distinguish.

In addition, the conventional method converts AC power into DC and applies it between the field circuit and the ground, so a rectifier circuit is installed, which causes reliability problems because many parts are installed in the rotating part. Ta.

[Problem to be solved by the invention]

The above-mentioned "rotor coil ground fault detection monitor" consists of a power supply rotating transformer, an output rotating transformer, a detection module and a relay, and has a complex structure, and a detection module made of electronic components is attached to the rotating part. Therefore, there was a problem with reliability. In addition, in the method of detecting changes in the primary side current or negative side impedance using a power supply rotating transformer, due to the characteristics of the rotating transformer, if the ground fault resistance is high,
There was a problem in that changes in the power supply and impedance on the primary side of the power supply rotating transformer became small, making it difficult to identify a ground fault. In addition, in each method, a rectifier circuit is attached to the rotating part in order to convert AC power into DC and apply it between the field circuit and the ground. As a result, the structure becomes complicated and there are many parts that rotate once, which poses a problem in reliability.

The present invention reduces the number of rotating parts and simplifies the structure,
The object of the present invention is to provide a non-contact field ground fault detection device that improves ground fault detection performance.

[Means to solve the problem]

The purpose of the above is to install a rotating transformer for power and signals on a brushless synchronous machine, connect an AC power source to the fixed part of the primary side of the rotating transformer, and connect one terminal of the rotating part of the secondary side to the main shaft through a limiting resistor. The other terminal is connected to the field circuit through the primary rotating part of the signal rotating transformer, and the secondary fixed part of the signal rotating transformer is configured with a circuit that determines the signal according to the ground current. This is achieved by providing a non-contact field ground fault detection device connected to a detector.

[Effect]

By applying AC power from the fixed part of the primary side of the rotating power transformer, AC power is supplied to the rotating part without contact, and it is connected between the field circuit and the ground via the limiting resistor and the rotating part of the primary side of the rotating signal transformer. AC power is applied to. When a ground fault occurs, the AC power supply causes a ground fault current to flow from the ground fault location in the field circuit to the ground through the signal rotary transformer and the limiting resistor. In that case, a voltage signal corresponding to the ground current is generated at the secondary fixed portion of the signal rotary transformer. By determining the level of the voltage signal, it is possible to determine a field ground fault in the one rotation section without contact.

In addition, the limiting resistor can suppress short-circuit current when completely grounded, and protect the detection device and field circuit.

By installing rotary transformers for power supply and signals in this way, the structure is simple, and discrimination can be performed at the fixed part without installing a rectifier circuit or discrimination circuit on the rotating part. The detection performance can be improved by this.

〔Example〕

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

In the figure, a stator 1 of a synchronous machine, a rotor 2a of a synchronous machine,
And the rotor 2 of the brushless exciter directly connected to this
b. In a brushless synchronous machine equipped with a stator 3 of a brushless exciter, a power supply rotating transformer 4 and a signal rotating transformer 6 consisting of a fixed part and a rotating part are installed in the main body of the brushless synchronous machine, and AC power is supplied from the outside. 7 is connected to the primary side fixed part of the power supply rotary transformer 6, one terminal of the secondary side rotation part of the power supply rotary transformer 6 is grounded to the main shaft through the limiting resistor 8, and the other terminal is connected to the signal rotary transformer 4. It is connected to the field circuit through the primary rotating part.

Further, a ground fault detector 5 constituted by a circuit for determining field ground faults is connected to the secondary fixed portion of the signal rotary transformer 4.

When a ground fault occurs in the field circuit of a synchronous machine, the ground fault current becomes a limiting resistance using the power supply rotating transformer 6 as a power source.

It also flows through the primary rotating part of the signal rotating transformer 4. As a result, a voltage signal is generated at the secondary fixed portion of the signal rotary transformer 4. A ground fault in the field circuit can be detected without contact using a detector that determines the level of the voltage signal.

Further, the limiting resistor 8 can protect the field circuit and the detection device in the event of a ground fault.

Furthermore, this method can also display the insulation resistance of the field circuit during operation.

In the figure, reference numeral 2 indicates a rotating part. [Effects of the Invention] The non-contact field ground fault detection device of the present invention can improve ground fault detection performance and simplify the structure.

[Brief explanation of the drawing]

The figure is a circuit configuration diagram of a non-contact field ground fault detection device showing one embodiment of the present invention.

Claims (1)

[Claims] 1. A brushless synchronous machine is equipped with a power supply rotary transformer for detecting a field ground fault of the synchronous machine and a signal rotary transformer, and an alternating current voltage is applied to the primary fixed part of the power supply rotary transformer. One terminal of the next rotating part is grounded to the main shaft through a current limiting resistor, and the other terminal is connected to the field circuit through the primary rotating part of the signal rotating transformer, and the secondary side of the signal rotating transformer is fixed. A non-contact type field ground fault detection device, characterized in that a detector including a circuit for determining the field ground fault is provided in the part.