阅读说明：本技术 大安匝数电流互感器绝缘受潮处理的干燥装置及干燥方法 (Drying device and drying method for insulating and wetting treatment of current transformer with large ampere turns ) 是由 林建军 姜兆福 张鸿升 李晓彬 于 2021-06-24 设计创作，主要内容包括：大安匝数电流互感器绝缘受潮处理的干燥装置及干燥方法。目前工频谐振法易破坏二次绝缘,使真空干燥时内部放电,无法达到额定电流干燥。本发明其组成包括：一组电流互感器二次绕组(1),一组电流互感器二次绕组、电压表(2)并联连接,其中一端接口为S1接口,另一端与电流表串联后为S2接口,一组电流互感器二次绕组为4个,其中前3个分别与电流表(3)串联后再与另一个电流表连接,S1接口、S2接口分别连接低频电源装置的输出接口(8),低频电源装置的上方分别安装有接地线(4)、RS232通讯接口(5)、保护输入接口(6)、保护输出接口(7)、输出接口、保险装置(9)、电源(10)。本发明用于大安匝数电流互感器绝缘受潮处理的干燥装置。(A drying device and a drying method for insulating and wetting treatment of a current transformer with large ampere turns are provided. At present, secondary insulation is easy to damage by a power frequency resonance method, so that internal discharge is caused during vacuum drying, and drying at rated current cannot be achieved. The invention comprises the following components: a set of current transformer secondary winding (1), a set of current transformer secondary winding, voltmeter (2) parallel connection, wherein one end interface is the S1 interface, be the S2 interface after the other end establishes ties with the ampere meter, a set of current transformer secondary winding is 4, wherein preceding 3 establish ties with ampere meter (3) respectively and then are connected with another ampere meter, the S1 interface, the output interface (8) of low frequency power supply unit are connected respectively to the S2 interface, earth connection (4) are installed respectively to the top of low frequency power supply unit, RS232 communication interface (5), protection input interface (6), protection output interface (7), the output interface, safeties (9), power (10). The invention relates to a drying device for insulating and damping treatment of a current transformer with large ampere turns.)

1. The utility model provides a big ampere of turn current transformer is insulating drying device who wets processing which constitutes and includes: a set of current transformer secondary winding, characterized by: a set of current transformer secondary winding, voltmeter parallel connection, wherein one end interface be the S1 interface, be the S2 interface after the other end establishes ties with the ampere meter, a set of current transformer secondary winding be 4, wherein preceding 3 be connected with another ampere meter after establishing ties respectively, S1 interface S2 interface connect low frequency power supply unit ' S output interface respectively, low frequency power supply unit ' S top install earth connection, RS232 communication interface, protection input interface, protection output interface respectively output interface, safeties, power, low frequency power supply unit ' S below install master switch, regulation voltage button, display screen respectively.

2. The drying method of the drying device for the insulation damp treatment of the current transformer with large ampere turns of claim 1 is characterized in that: the method comprises the following steps:

firstly, a primary winding of a current transformer is short-circuited, and low-frequency voltage capable of being automatically adjusted is applied to a secondary winding of the current transformer, so that a coil reaches rated current, and heating and drying are realized;

the method comprises the steps that an alternating current power supply is adopted, a low-frequency power supply is used for replacing a power frequency power supply, the voltage applied to the secondary side of the CT is reduced, an automatically adjustable low-frequency power supply device which outputs 0-400V/0-5A and has a frequency range of 1-50 Hz is selected, the device automatically boosts and reduces the frequency under the condition that the input CT secondary rated constant current mode is set in the low-frequency power supply device, the constant current is kept and is output to the secondary side of the CT after the set current is achieved, the aim of drying the CT is achieved, and the maximum voltage applied to the secondary side of the CT is 400V;

the low-frequency vacuum short-circuit drying method of the current transformer does not discharge the secondary coil by voltage, heating and vacuumizing are carried out simultaneously, vacuumizing needs to be carried out for at least 20 times, and 20 times of circulation needs to take 120 hours;

the specific operation process is as follows: the low-frequency power supply output is connected to a CT secondary protection terminal, other terminals are short-circuited and are set as a unit, a temperature control module, a vacuum degree control module, a time control module and a drying air heating control module are set as a unit, the upper and lower limit temperatures, the vacuum degree and the drying air temperature of CT drying are set through a temperature sensor and a pressure sensor, the starting and stopping of the low-frequency power supply, a vacuum pump and a drying air heater are automatically and timely controlled, remote control and monitoring functions can be realized through a camera and a wireless transmission system, and the aim of unattended operation of a drying field in the whole drying intermediate process is achieved.

Technical Field

The invention relates to a drying device and a drying method for insulating and wetting a current transformer with large ampere turns.

Background

For a less ampere turn, like 1250/5's current transformer handles insulating heating problem that wets, can make it reach rated current at CT secondary pressurization with ordinary 400V voltage regulator, required equipment is simple, and the effect is better, but great to ampere turn, like 1250/1's current transformer handles insulating and wets, when secondary coil needs 1600V voltage, the secondary can reach rated current 4A (4 groups of secondary are parallelly connected), the voltage hardly satisfies the requirement, can adopt series resonance vacuum short-circuit drying at this moment, carry out voltage compensation, but to ampere turn bigger if: according to the LBT5-220W2 type CT produced by Atahai big electrical apparatus Co Ltd in 2012, when the power frequency secondary current reaches the rated current (1 ampere), the secondary voltage reaches 8000V, but the secondary insulation design is about 2000V, the secondary insulation is easily damaged by adopting a power frequency resonance method, the internal discharge is easily caused during vacuum drying, and the drying cannot reach the rated current.

Disclosure of Invention

The structure and the method achieve the aim of drying by reducing the power supply frequency for drying the dried current transformer with large ampere-turns, reducing the voltage, avoiding the discharge of a secondary coil, and simultaneously performing heating and vacuumizing.

The above purpose is realized by the following technical scheme:

the utility model provides a big ampere of turn current transformer is insulating drying device who wets processing which constitutes and includes: a set of current transformer secondary winding, voltmeter parallel connection, wherein one end interface is the S1 interface, is the S2 interface after the other end establishes ties with the ampere meter, a set of current transformer secondary winding be 4, wherein preceding 3 establish ties with the ampere meter respectively and then is connected with another ampere meter, S1 interface S2 interface connect low frequency power supply unit ' S output interface respectively, low frequency power supply unit ' S top install earth connection, RS232 communication interface, protection input interface, protection output interface, safeties, power respectively, low frequency power supply unit ' S below install master switch, regulation voltage button, display screen respectively.

A drying device and a drying method for insulating and wetting treatment of a current transformer with large ampere turns comprise the following steps:

firstly, a primary winding of a current transformer is short-circuited, and low-frequency voltage capable of being automatically adjusted is applied to a secondary winding of the current transformer, so that a coil reaches rated current, and heating and drying are realized;

the method comprises the steps that an alternating current power supply is adopted, a low-frequency power supply is used for replacing a power frequency power supply, the voltage applied to the secondary side of the CT is reduced, an automatically adjustable low-frequency power supply device which outputs 0-400V/0-5A and has a frequency range of 1-50 Hz is selected, the device automatically boosts and reduces the frequency under the condition that the input CT secondary rated constant current mode is set in the low-frequency power supply device, the constant current is kept and is output to the secondary side of the CT after the set current is achieved, the aim of drying the CT is achieved, and the maximum voltage applied to the secondary side of the CT is 400V;

the low-frequency vacuum short-circuit drying method of the current transformer does not discharge the secondary coil by voltage, heating and vacuumizing are carried out simultaneously, vacuumizing needs to be carried out for at least 20 times, and 20 times of circulation needs to take 120 hours;

the specific operation process is as follows: the low-frequency power supply output is connected to a CT secondary protection terminal, other terminals are short-circuited and are set as a unit, a temperature control module, a vacuum degree control module, a time control module and a drying air heating control module are set as a unit, the upper and lower limit temperatures, the vacuum degree and the drying air temperature of CT drying are set through a temperature sensor and a pressure sensor, the starting and stopping of the low-frequency power supply, a vacuum pump and a drying air heater are automatically and timely controlled, remote control and monitoring functions can be realized through a camera and a wireless transmission system, and the aim of unattended operation of a drying field in the whole drying intermediate process is achieved.

Has the advantages that:

1. the invention relates to a drying device and a drying method for insulating and humidifying a current transformer with large ampere turns.

2. The automatic adjustable variable frequency power supply device selectively outputs 0-400V/0-5A and has a frequency range of 1-50 Hz, and under the condition that a secondary rated constant current mode of CT input is set in the variable frequency power supply device, the device automatically boosts and reduces the frequency, so that the constant current output to the secondary side of the CT is kept after the current is set, and the aim of drying the CT is fulfilled.

Description of the drawings:

FIG. 1 is a diagram of the variable frequency heating electrical wiring of the present invention.

Fig. 2 is a structural diagram of a low-frequency power supply device of the present invention.

Wherein: 1. the current transformer secondary winding, 2, a voltmeter, 3, an ammeter, 4, a grounding wire, 5, an RS232 communication interface, 6, a protection input interface, 7, a protection output interface, 8, an output interface, 9, a safety device, 10, a power supply, 11, a main switch, 12, a voltage regulating button, 13 and a display screen.

The specific implementation mode is as follows:

example 1:

the utility model provides a big ampere of turn current transformer is insulating drying device who wets processing which constitutes and includes: a set of current transformer secondary winding 1, a set of current transformer secondary winding, voltmeter 2 parallel connection, wherein one end interface is the S1 interface, is the S2 interface after the other end establishes ties with the ampere meter, a set of current transformer secondary winding be 4, wherein preceding 3 establish ties with ampere meter 3 respectively and then be connected with another ampere meter, the S1 interface S2 interface connect low frequency power supply unit ' S output interface 8 respectively, low frequency power supply unit ' S top install respectively that earth connection 4, RS232 communication interface 5, protection input interface 6, protection output interface 7 output interface, safety device 9, power 10, low frequency power supply unit ' S below install master switch 11, regulation voltage button 12, display screen 13 respectively.

Example 2:

the drying method of the drying device for the insulation moisture treatment of the current transformer with large ampere turns according to the embodiment 1 comprises the following steps:

firstly, a primary winding of a current transformer is short-circuited, and low-frequency voltage capable of being automatically adjusted is applied to a secondary winding of the current transformer, so that a coil reaches rated current, and heating and drying are realized;

the method comprises the steps that an alternating current power supply is adopted, a low-frequency power supply is used for replacing a power frequency power supply, the voltage applied to the secondary side of the CT is reduced, an automatically adjustable low-frequency power supply device which outputs 0-400V/0-5A and has a frequency range of 1-50 Hz is selected, the device automatically boosts and reduces the frequency under the condition that the input CT secondary rated constant current mode is set in the low-frequency power supply device, the constant current is kept and is output to the secondary side of the CT after the set current is achieved, the aim of drying the CT is achieved, and the maximum voltage applied to the secondary side of the CT is 400V;

the low-frequency vacuum short-circuit drying method of the current transformer does not discharge the secondary coil by voltage, heating and vacuumizing are carried out simultaneously, vacuumizing needs to be carried out for at least 20 times, and 20 times of circulation needs to take 120 hours;

the specific operation process is as follows: the low-frequency power supply output is connected to a CT secondary protection terminal, other terminals are short-circuited and are set as a unit, a temperature control module, a vacuum degree control module, a time control module and a drying air heating control module are set as a unit, the upper and lower limit temperatures, the vacuum degree and the drying air temperature of CT drying are set through a temperature sensor and a pressure sensor, the starting and stopping of the low-frequency power supply, a vacuum pump and a drying air heater are automatically and timely controlled, remote control and monitoring functions can be realized through a camera and a wireless transmission system, and the aim of unattended operation of a drying field in the whole drying intermediate process is achieved.

For a large CT with a higher ampere-turn number, because the voltage of the saturation inflection point of the iron core is very high (from thousands of volts to tens of thousands of volts), the secondary winding is easy to be subjected to insulation breakdown discharge, which cannot be realized by a frequency electric drying method, for example: according to the test of the voltage-current characteristics of the protection winding TPY, the LBT5-220W2 type CT produced by Atahai big-mutual electrical apparatus company, Inc. in 2012, when the power frequency secondary current reaches the rated current (1 ampere), the secondary voltage reaches 8000V, but the secondary insulation design is about 2000V, and the power frequency resonance method can not reach the rated current at all;

in order to lower the saturation point of the iron core, a method for reducing the power frequency can be adopted, and the point can be described by a formula of induced electromotive force of the transformer;

E = 4.44fWBS = K f B

K = 4.44WS

wherein E-induced electromotive force (V);

f-supply frequency (Hz);

w is the number of coil turns;

b-magnetic flux density (T)

S-core section area (m 2)

K-constant of proportionality

As can be seen from the above formula, if B is kept constant, since the K value is constant, when the power supply frequency is reduced by 10 times, the induced voltage is also reduced by 10 times, and the voltage of the core volt-ampere characteristic curve inflection point (core saturation) can be reduced from several thousand volts to several hundred volts;

the principle is that a primary winding of a current transformer is short-circuited, low-frequency voltage capable of being automatically adjusted is applied to a secondary winding, so that a coil reaches rated current, heating and drying are realized, compared with direct current, the loss of the secondary winding is heated except the loss of the secondary winding when alternating current is conducted, the loss of the primary winding and the eddy current loss of an iron core working in saturated excitation are also heated, so that the heating speed is higher than that of direct current, residual magnetic flux of the iron core of the transformer can be caused by the direct current, the precision of the transformer is reduced, residual magnetism cannot be generated when alternating current is conducted, the voltage applied to a secondary side of CT can be greatly reduced by using a low-frequency power supply to replace a power-frequency power supply, the automatic adjustable variable-frequency power supply device is very safe to work, if an automatic adjustable variable-frequency power supply device which outputs 0-400V/0-5A and has a frequency range of 1-50 Hz, and under the set input CT secondary rated current mode in the variable-frequency power supply device, the automatic variable-frequency power supply device automatically boosts, Reducing the frequency, keeping constant current output to the CT secondary side after the set current is achieved, and achieving the aim of CT drying, wherein the highest voltage applied to the CT secondary side is 400V;

through the analysis, the low-frequency vacuum short-circuit drying method of the current transformer is feasible, the voltage does not cause the secondary coil to discharge, and the heating and the vacuumizing can be simultaneously carried out. Practice proves that if the power frequency vacuum short-circuit drying method is used for achieving the drying purpose, vacuumizing is usually carried out for at least 20 times, vacuum breaking is also carried out for at least 20 times, and 20 times of circulation requires as much as 120 hours, namely if the low-frequency vacuum short-circuit drying method is adopted for measurement, the drying time can be reduced by 5 days at least, the workload can be reduced to the maximum extent, and the working efficiency can be improved;

the low-frequency vacuum short-circuit drying method is that the frequency is reduced to reduce the voltage, so that the secondary coil is not discharged, the heating and the vacuum pumping can be simultaneously carried out, the specific working process can connect the output of a low-frequency power supply to a CT secondary protection terminal, and other terminals are short-circuited to form a unit; setting a temperature control module, a vacuum degree control module, a time control module and a drying air heating control module as a unit, setting upper and lower limit temperatures, vacuum degrees and drying air temperatures of CT drying through temperature and pressure sensors, and automatically controlling starting and stopping of a low-frequency power supply, a vacuum pump and a drying air heater at fixed time; the remote control and monitoring functions can be realized through the camera and the wireless transmission system, the unattended operation of a drying site in the whole drying intermediate process is realized, the workload of workers is reduced to the maximum extent again, and the working efficiency is improved;

in the variable-frequency heating electrical wiring diagram of fig. 1, output terminals S1 and S2 of the low-frequency power supply device of fig. 2 are connected to 4 windings of the secondary windings TPY of the current transformer, wherein the windings are connected in parallel by 3S, 4S, 5S and 6S.