RU2553281C1 - Device for detecting partial discharges - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device for detecting partial discharges comprises high-voltage direct-current power supply source with high-voltage capacitor connected to it through one position of switch key; through the second position of switch key the tested facility is connected with a sensor connected to the facility. Oscilloscope is coupled to the sensor through a shielded wire. Direct-current power supply source, capacitor and sensor are interconnected at common point and grounded. The technical effect is as follows: device for detecting partial discharges allows diagnosing direct-current machines.

EFFECT: potential detection of partial discharge signals in insulation of direct-current motors.

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Description

The invention relates to the field of measuring electrical quantities and can be used to detect signals of partial discharges in the electrical insulation of DC motors when diagnosing the occurrence of insulation defects.

A device for measuring partial discharges is known [RU 2402092 C1, IPC Н01Н 9/50 (2006.01), publ. 20.10.2010], containing a partial discharge sensor located inside the electrostatic screen and having a common ground, made in the form of an inductor, analog-to-digital and optical converters and a common power supply unit for converters. The input of the analog-to-digital converter is connected to the potential output of the inductor, and its output is connected to the input of the optical converter, the output of which is connected to an optical cable connected to an external measuring device. The device contains an amplifier with a negative gain and is equipped with a signal and magnetizing windings located on the electrostatic screen. The signal winding is connected to the input of the amplifier, to the output of which a magnetizing winding is connected. The items listed above have a common ground.

A device is known for the continuous monitoring of partial discharges in the insulation of three-phase high-voltage devices under operating conditions, consisting of at least an active part in the form of a system of electrically connected elements connected under high voltage and surrounded by insulation layers [RU 2393494 C1, IPC G01R 31/02 (2006.01), publ. 06/27/2010]. In addition, this device contains circuits for processing, recording the partial discharge signal and at least one sensor-receiver of the partial discharge signal, which is used as the active part of a three-phase high-voltage apparatus. Partial discharge signals are measured simultaneously on all three phases of the high-voltage apparatus at the common point of the active part of this apparatus using low-voltage measuring voltage transformers connected by an open triangle circuit.

A device for monitoring the characteristics of partial discharges [RU 2019850 C1, IPC5 G01R 31/12, publ. September 15, 1994], selected as a prototype, comprising a test transformer, a high voltage capacitor, a high-pass filter, a measuring cable, and a recording device connected in series. One of the capacitor plates is the current-carrying core of the test object, parallel to which there is a conductive plate, which is the second capacitor plate and connected to the input of the high-pass filter, made in the form of a segment of a two-wire line with distributed parameters. The capacitance C _{C of the} high voltage capacitor and the wave impedance RHK of the coaxial measuring cable satisfy the relation

where T _and is the pulse duration of the partial discharge.

The recording device includes a serially connected broadband integrating amplifier, a comparator, a pulse counter and an indicator.

A common disadvantage of analogues is that these partial discharge diagnostic devices operate on alternating current. For DC machines, such devices are not acceptable.

The objective of the invention is to provide a device for detecting partial discharges, allowing to diagnose DC machines.

The problem is solved due to the fact that the device for detecting partial discharges as in the prototype contains a high voltage capacitor and a recording device.

According to the invention, a high-voltage capacitor is connected in parallel to the high-voltage DC power supply through one of the positions of the switching key, through another position of which a test object is connected to the capacitor, to which the sensor is connected, and an oscilloscope is used as a recording device, which is connected to the sensor through a shielded wire, and DC power supply, capacitor and sensor connected to a common point and grounded.

Thus, due to the use of a power capacitor as a source of pulsed DC voltage, the proposed device allows to detect partial discharges in the insulation of the windings of DC motors, which will allow to identify insulation defects at the initial stage of their appearance.

Figure 1 schematically shows the inventive device.

The device for detecting partial discharges contains a high-voltage DC power supply 1, in parallel with which a high-voltage capacitor 2 is connected through one of the positions of the switching key 3. Through another position of the switching key 3, the test object 4 (IO) is connected to the capacitor 2, to which the sensor 5 is connected ( D), which through a shielded wire is connected to the oscilloscope 6 (O). DC power supply 1, capacitor 2 and sensor 5 (D) are connected to a common point and grounded.

As a sensor 5 (D), a low inductance resistor is used.

The proposed device operates as follows. To charge the high-voltage capacitor 2, a power source 1 is used. The charged capacitor 2 is switched by a switching key 3 from the power source 1 to the test object 4 (IO), for example, to the winding section of a DC motor. When discharging, the capacitor 2 produces a pulsed DC voltage, which passes through the test object 4 (IO). If the voltage value is sufficient, then partial discharges appear, which are recorded by the sensor 5 (D) and recorded by the oscilloscope 6 (O), which allows you to present the received data in the form of graphs or tables for further processing. Grounding serves as a protection for humans against electric shock.

Claims (1)

A device for detecting partial discharges, comprising a high-voltage capacitor and a recording device, characterized in that a high-voltage capacitor is connected in parallel to the high-voltage DC power supply through one of the positions of the switching key, through another position of which a test object is connected to the capacitor, to which the sensor is connected, and An oscilloscope was used as a recording device, which is connected to the sensor through a shielded wire, and the power supply is constant first current, the capacitor and the sensor are connected to a common point and grounded.