RU103191U1 - MOBILE INSTALLATION FOR DIAGNOSTICS OF POWER TRANSFORMERS - Google Patents

Abstract

A mobile installation for diagnostics of power transformers, containing a measuring unit placed on the vehicle chassis, made with the ability to measure and indicate the effective values of currents and voltages of a three-phase circuit, the average value of measured voltages, their frequency and total three-phase active power, an autonomous power frequency generator, made with the possibility of generating a three-phase system of alternating voltages, in which the ratio of each of the line voltages to its average value and to the arithmetic mean of the three line-to-line voltages of the system lies within 1.10-1.12 and 0.97-1.03, respectively, a three-phase set of measuring transformers current accuracy class not less than 0.2% and a set of wires for connecting the specified equipment to each other and a three-phase cable for connecting to a diagnosed power transformer in accordance with standardized measurement schemes for losses and no-load current at rated voltage nii.

Description

Technical field

The utility model relates to diagnostic tools for power transformers and is intended for use in the field of their operation during the prevention and energy audit. The preferred field of application of the device is the determination of current and idle losses of power transformers 10 (6) / 0.4 kV. Periodic monitoring of idling parameters is especially relevant for power transformers that have been in operation for more than 20 years.

State of the art

Current GOST 3484.1-88 “Power transformers. Methods of electromagnetic tests ”standardizes two modes of measuring parameters (current and active losses) of idling of power three-phase transformers:

- measurements at rated voltage;

- measurements at low voltage (carried out with a shorted secondary winding of one phase).

Currently, these measurements at rated voltage are carried out at the manufacturer's stand (during acceptance tests), and at the field of operation (when diagnosing transformers), the idling parameters are periodically measured at low voltage using mobile laboratories specially equipped for this purpose.

Known mobile laboratories installed on self-propelled chassis for testing electrical equipment at geographically dispersed operating facilities [RU 2054247, IPC A01J 7/00, 1996, RU 60734 IPC G01R 29/20, 2006].

The disadvantage of these analogues is the lack of specialization of the installed equipment for the diagnosis of power transformers (including the measurement of their idle parameters).

Known designed for the diagnosis of power transformers mobile laboratory "Mega-1", manufactured by the industrial association "Mega Engineering" [www.megavan.ru]. The Mega-1 laboratory has a K-04 complex for low-voltage measurements of transformer parameters, including idling at low voltage. This device is selected as a prototype.

The prototype contains (see passport of the K-04 block) a isolating power transformer located in the van, a continuously adjustable measuring autotransformer, a measuring unit configured to measure current, voltage and power, as well as connecting cables.

The disadvantage of the prototype is its unsuitability for direct measurements of idling parameters at rated voltage according to the GOST 3484.1-88 methodology. In addition, the prototype installation is not autonomous - for measurements, it requires external power supply, which is not always provided at operational sites with the power transformer disconnected.

The absence of mobile units specially equipped for autonomous on-line measurement of the idling parameters of power transformers in the field of operation in the nominal voltage mode leads to the fact that at present, when diagnosing power transformers, the idling parameters are measured only in the low voltage mode. This reduces the reliability of diagnostics of the state of the transformer magnetic circuit, does not give grounds for the timely shutdown of transformers with defects in the magnetic circuit (for example, short circuits and insulation failures between its laminated sheets) and, thereby, increases the likelihood of emergency situations.

The objective of the utility model is to eliminate this drawback.

Utility model creature disclosure

The technical result of the utility model is to increase the reliability of the diagnostics of power transformers carried out in operating conditions.

The subject of the utility model is a mobile installation for the diagnosis of power transformers, containing the following on the vehicle chassis:

- a measuring unit configured to measure and display the effective values of currents and voltages of a three-phase circuit, the average value of the measured voltages, their frequency and the total three-phase active power;

- an autonomous generator of industrial frequency, made with the possibility of generating a three-phase system of alternating voltages, in which the ratio of each of the linear voltages to its average value and to the arithmetic average of three linear voltages of the system is in the range of 1.10-1.12 and 0.97-1 , 03, respectively;

- a three-phase set of measuring current transformers of accuracy class not lower than 0.2%;

- a set of wires for connecting the specified equipment to each other and a three-phase cable for connecting to the diagnosed power transformer in accordance with standardized schemes for measuring losses and open circuit current at rated voltage.

The use of a mobile unit with a combination of the above features makes it possible to promptly and autonomously perform measurements of idling parameters at rated voltage in the field of operation of power transformers, standardized by current GOST 3484.1-88. These parameters reflect the state of the magnetic circuit of the power transformer more reliably than similar parameters measured at low voltage, and the increase in periodically measured losses allows timely detection of the appearance of defects in the magnetic circuit.

List of drawings

Figure 1 presents a mobile installation in the process of diagnosing a power transformer, and figure 2 a diagram of the electrical connections of the equipment.

Utility Model Implementation

Figure 1 shows the chassis 1 of the vehicle and the equipment placed on it:

measuring unit 2,

autonomous, for example, industrial frequency diesel generator 3,

set of wires 4 and three-phase cable 5.

three-phase set of measuring transformers 6 current.

The diagnosed power transformer 7 is connected to the installation by cable 5.

Measuring unit 2 provides measurements with an error of not more than 0.5% and an indication of the effective values of currents and voltages of the three-phase circuit, frequency, average value of the measured voltages, their frequency and the total three-phase active power. As block 2 can be used, for example, a universal power meter VU-01, manufactured by NPP Energopribor LLC, Vladimir.

Generator 3 provides the possibility of generating a three-phase system of alternating voltages, in which the ratio of each of the linear voltages to its average value and to the arithmetic average of three linear voltages of the system lies in the range of 1.10-1.12 and 0.97-1.03, respectively. The frequency of the output voltage of the generator 3 can be set (by changing the speed of the diesel engine) equal to the nominal value of the industrial frequency of 50 Hz with an accuracy of ± 1%. As the generator 3, for example, a DCA-25ESK diesel generator manufactured by the Japanese company DENYO Co., Ltd. can be used.

Measuring transformers 6 current have an accuracy class of 0.2% or 0.1%.

A set of wires 4 is designed to make the necessary connections between the measuring unit 2, the generator 3 and the measuring transformers 6 in accordance with the circuit shown in figure 2, which is standardized by GOST 3484.1-88 for measuring the open circuit parameters of power transformers at rated voltage.

Cable 5, several tens of meters long, is used to connect the unit to the low-voltage three-phase winding of the diagnosed power transformer 7.

The measurement of the idling parameters of the power transformer using the proposed installation is as follows.

The chassis 1 is located at a safe distance from the power transformer 7, which can be operated, for example, as part of a high-voltage transformer substation. The necessary removal is ensured by the choice of cable length 5. Cable 5 is connected to the low-voltage winding of the transformer 7 after disconnecting (or expanding) its other windings and applying the necessary grounding.

Power supply unit 2 is supplied with a voltage of 220 V from one of the phases of the generator 3.

After starting and the necessary heating of the diesel engine, the frequency of the output voltage of the generator 3 is set to 50 Hz by adjusting the speed of rotation of the engine, and the voltage is supplied to the transformer 7 using the controls of the generator. The value of the supplied voltage is set equal to the nominal value of the connected low-voltage winding of the tested transformer ( typically 400 V). Block 2 (universal wattmeter) at the same time measure the output frequency of the generator, the values of three phase voltages, the average voltage value of three phases. These values are controlled for compliance with the requirements of GOST 3484.1-88. Then block 2 measures the currents, active idling power for each phase and the total active idling power of the transformer 7. The results of these measurements are recorded in the protocol.

In this case, block 2 may not control the requirements of GOST 3484.1-88 in terms of the degree of sinusoidality of the stresses (the ratio of the effective value to the average) and the degree of symmetry of the three-phase system of test voltages (their deviations from the arithmetic mean value), since the generator 3 used meets these requirements.

Thus, a mobile installation with the claimed combination of features allows you to quickly and reliably produce in full accordance with the current standard "Power transformers. Methods of electromagnetic tests ”measuring the idling parameters of power transformers at rated voltage not only at the factory, but also in the field of operation.

Claims (1)

A mobile unit for diagnosing power transformers, comprising a measuring unit located on the vehicle chassis, configured to measure and display the current values of currents and voltages of a three-phase circuit, the average value of the measured voltages, their frequency and the total three-phase active power, an autonomous industrial frequency generator made with the possibility of generating a three-phase system of variable voltages, in which the ratio of each of the linear voltages to its average value to the arithmetic mean of the three linear voltages of the system lies within 1.10-1.12 and 0.97-1.03, respectively, a three-phase set of measuring current transformers with an accuracy class of at least 0.2% and a set of wires for connecting the specified equipment between themselves and a three-phase cable for connecting to the diagnosed power transformer in accordance with standardized schemes for measuring losses and open circuit current at rated voltage.