Shanghai Huabang Industrial Business Network - Harmonic eliminator

[Harmonic eliminator]LXQ II series harmonic elimination resistor

2026-6-13 21:13:44

The LXQ II series harmonic eliminator resistor (hereinafter referred to as the harmonic eliminator) is a nonlinear harmonic damping device installed between the neutral point Y0 of the primary winding of a 6-35kV voltage transformer (hereinafter referred to as the PT) and the ground. It plays a role in current limiting and damping, and can effectively suppress inrush current and PT ferromagnetic resonance. When the neutral point of the power grid where the 6-35kV substation is located is not grounded, the PT primary winding on the busbar will become the only metal channel for the neutral point ungrounded power grid to ground. The charging and discharging of the relative ground capacitance of the power grid will inevitably pass through the PT primary winding, causing deep saturation of its iron core. Therefore, when the grounding of the power grid disappears, a surge of several amperes will appear in the primary winding of the PT. By melting the 0.5A fuse of the PT, the harmonic eliminator can effectively limit the surge of the primary winding of the PT.

When the busbar is unloaded or there are few outgoing lines, ferromagnetic resonance overvoltage may occur, resulting in unstable phase voltage, ground indication misoperation, PT high-voltage fuse melting, and other phenomena. Choosing LXQII series anti harmonic resistors will greatly reduce the occurrence of this situation.

Preface number	project		technical indicators
			LXQII10 (6) type	LXQ (D) II10 (6) type	LXQ (D) Type II	LXQ (D) II35 type
one	The resistor passes through AC0.3mA (voltage and resistance at peak current)	U0.3mA (V. peak/�� 2)	one hundred and thirty ±30	one hundred and thirty ±30	four hundred and fifty ±50	four hundred and fifty ±50
two	The resistor passes through AC3mA (voltage and resistance at peak current)	U3mA (V. peak/�� 2)	five hundred ±100	five hundred ±100	one thousand and four hundred ±150	one thousand and four hundred ±150
		R3mA (k��)	��180	��180	��550	��550
three	Is the power frequency voltage at both ends of the resistor limited to 50H		no restrictions	Limit 3kV peak/�� 2 or below	no restrictions	Limit 5kV peak/�� 2 or below
four	Thermal capacity through 100mA peak current for 2 hours		1. No obvious damage 2. The change in U0.3mA before and after the heat capacity test is ��± 5%
five	Thermal capacity through 500mA peak current for 10 minutes		1. Any obvious damage 2. The change in U0.3mA before and after the heat capacity test is ��± 10%
make use item document	Inside and outside the house, installed near the transformer, the harmonic eliminator has a rainproof function and should not be directly exposed to sunlight and rain
	Environmental temperature -40 ��~60 ��
	The frequency of the AC power system is 50Hz or 60Hz
	Areas with earthquake intensity below 8 degrees

LXQ �� series harmonic elimination resistor

[Harmonic eliminator]6 to 35KV Nonlinear Resistance Harmonic Reduction Dampers

2026-6-13 19:37:23

1�� Product Introduction:
The TXQ (3) type 6-35kV voltage transformer neutral point nonlinear resistance harmonic damper (referred to as harmonic damper) is a nonlinear resistance harmonic damping device installed between the neutral point of the primary winding Y of the 6-35kV voltage transformer (hereinafter referred to as transformer or PT) and the ground. The product model of the harmonic eliminator - TXQ represents a harmonic eliminator designed according to traditional appearance; TXQ3 refers to a cylindrical harmonic eliminator designed for the third modification, with exposed resistor surfaces and no need for insulation jacket protection. The only difference between the two is their appearance, but their electrical performance is completely the same.
The DC electrical characteristics of TXQ (3) type 6-35kV harmonic eliminator are similar to traditional LXQ and RXQ type harmonic eliminators, but the structural design has been greatly improved from the perspective of increasing the thermal capacity of the harmonic eliminator. The harmonic eliminator uses SiC with excellent electrical performance and ultrafine particles as the substrate; Pressed into high-density, round cake shaped bodies by a large tonnage press; Under the restored atmosphere; Made by high-temperature sintering at thousands of degrees. The exposed surface structure of the resistor has been specially treated to withstand sunlight and rain, and can be directly used indoors and outdoors. It is popular among users due to its small size, light weight, fast heat dissipation, high strength, and easy installation.
2�� Application and Function
There are two related problems to be solved for voltage transformers in 6-35KV neutral point non effectively grounded power grids:
The overvoltage generated by the ferromagnetic resonance of the voltage transformer often causes insulation breakdown inside the equipment and discharge of the external insulation, and often leads to large-scale power outages due to delayed accident handling or the expansion of the accident.
2. The arc grounding in the power grid frequently burns out the voltage transformer.
The use of harmonic eliminators can effectively solve the above problems: eliminating or damping the ferromagnetic resonance overvoltage caused by the nonlinear excitation characteristics of voltage variation, which can lead to unstable phase voltage in the system; Can effectively suppress the overcurrent flowing through the voltage transformer winding during intermittent arc grounding, and prevent the burnout of the voltage transformer; Limit the inrush current generated in the primary circuit of the voltage transformer when the single-phase grounding disappears, which can damage the voltage transformer or cause the voltage transformer fuse to melt; When a single-phase grounding occurs in the system, it can protect the voltage transformer from damage for a long time.

3�� Main electrical performance:
Main performance parameters of TXQ (3) type 6-35KV harmonic eliminator (Table 1)

model			DC characteristic KV/mA	Nonlinear coefficient ��	Heat capacity 250mA/10min
TXQ (3) type 6-10KV	Electrified type		1.45��1.65/15	0.40��0.45	through
	Weak insulation type		1.38��1.45/15	0.40��0.45	through
	Plateau type		1.48��1.52/15	0.40��0.45	through
	Ultra small size		1.45��1.65/15	0.40��0.45	through
TXQ (3) type 35KV	Universal	A	4.0��4.2/42	0.40��0.45	through
	Universal	B	��2.80��2.85/50	0.30��0.40	through
	Weak insulation type		2.60��2.70/50	0.35��0.45	through
	Plateau type		1.90��2.10/15	0.35��0.45	through

The parameters in the table are typical product parameters. If the user has different requirements, production can be carried out according to the user's requirements.
4�� TXQ (3) type 6-35kV harmonic eliminator operating environment
1. Outdoor, installed near the transformer, although the harmonic eliminator has a rainproof function, it should not be directly exposed to sunlight and rain;
2. The ambient temperature ranges from -40 �� to+60 ��;
3. The frequency of the AC power system is 50HZ or 60HZ;
4. Areas with seismic intensity below 8 degrees.
5�� Installation of TXQ (3) type 6-35KV harmonic eliminator
1. Installation method: TXQ (3) type harmonic eliminator has a small volume and can be installed vertically or horizontally;
It can be directly fixed on the screw of the pressure transformer body (note that the fixing bolts of JDZJ-6-10 pressure transformers are not grounded). The grounding terminal of the harmonic eliminator needs to be connected to the grounding bolt. Also fixed on the bracket near the pressure change.

2. Wiring diagram (see Figure 1)

(1) When there are three single-phase voltage transformers (PT):
Before connecting the harmonic eliminator, the tails (X • Y • Z) of the three single-phase high-voltage windings are directly grounded or connected in parallel to the neutral point (0) for grounding.
When connecting the harmonic eliminator, the high-voltage winding tail or (0) directly grounded must be disconnected from the ground. The harmonic eliminator is connected between the neutral point (0) and the ground (the neutral point is no longer directly grounded).

(2) When the three-phase five column voltage transformer (PT) is used:
Before connecting the harmonic eliminator, the neutral point "0" of the three-phase five column voltage transformer should be directly grounded. When connecting the harmonic eliminator, the neutral point (0) must be disconnected from the ground, and the harmonic eliminator should be connected between the neutral point (0) and the ground (the neutral point is no longer directly grounded).
3. Main installation dimensions of harmonic eliminator:
(TXQ3 type, see Figure 2)

4. Parameter testing of TXQ (3) type harmonic eliminator
On site measurement can use a 1000V shaker to measure the insulation resistance of the harmonic eliminator, which is generally about 0.5M ��, and can be installed If it is necessary to measure the volt ampere characteristics and nonlinear coefficient �� of the harmonic eliminator, the following method can be used for measurement.
(1) Wiring diagram for measuring DC volt ampere characteristics: (see Figure 4)

(2) Testing the Nonlinear Coefficient �� Method:
When the DC characteristic of the harmonic eliminator is set to 15mA, the voltages U1 and U2 at both ends of the harmonic eliminator are measured at 50mA and 50mA DC, respectively; When the DC characteristics of the harmonic eliminator are 42mA or 50mA, the rigid nonlinear coefficients �� of the voltages U1 and U2 at both ends are measured for DC 100mA and 10mA, respectively
Voltage when U1=I1 is 50 (100) mA; Voltage when U2=I2 is 5 (10) mA;
lg
When I1=50 (100) mA, I2=5 (10) mA
lg=lg10=1
=lg

The mouth coefficient of the harmonic generator should comply with the values specified in Table 1.
(3) Thermal capacity spot check test: (see Figure 5)

Require the harmonic eliminator to withstand a 250mA power frequency current for 10 minutes without any burning or bursting phenomenon; When the harmonic eliminator is still in a high temperature condition, immediately spray water on the harmonic eliminator, and the harmonic eliminator body should be kept intact; After the harmonic eliminator is cooled and completely dried, its DC voltage change rate and DC nonlinear coefficient �� change rate are both not greater than 10%.

[Harmonic eliminator]SBX-WXYH microcomputer harmonic elimination device

2026-6-13 19:33:52

1. Model Description of SBX-WXYH Microcomputer Harmonic Elimination Device

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3. Technical Instructions for SBX-WXYH Microcomputer Harmonic Elimination Device
(1) Working power supply: AC 80-250V, 50-60Hz or DC 80-250V, power consumption less than 15W
(2) Environmental temperature: -20 to+50 ��;
(3) Environmental humidity: not exceeding 90% RH
(4) Eliminating resonant frequencies: 17Hz (1/3 division), 25Hz (1/2 division), 50Hz (power frequency), 150Hz (3rd harmonic)

4. Device features
(1) Suitable for various voltage levels and resonant frequencies (1/3 division, 1/2 division, power frequency, 3rd harmonic) with a wide range of applications;
(2) No need for tuning and debugging, automatically enters the running state after startup, with minimal maintenance;
(3) Distinguishable between ferromagnetic resonance, overvoltage, and single-phase grounding;
(4) Automatically display and record the occurrence time and related parameters (resonance frequency, amplitude) of ferromagnetic resonance;
(5) Can store 20 sets of fault information for recall and display;
(6) Configurable communication interface (RS232 or RS485);
(7) Output in contact closure mode or voice alarm output;

5. Working principle of the device
This device uses an 80C196 single-chip microcomputer as the core component to perform loop detection on PT open delta voltage (i.e. zero sequence voltage). Under normal operating conditions, if the voltage is less than 30V, the high-power harmonic elimination component (thyristor) inside the device is in a blocked state and has no impact on the system. When the voltage of the PT opening triangle is greater than 30V, it indicates that the system has malfunctioned. The device begins to collect data on the open delta voltage. By using digital signal processing techniques such as digital measurement, filtering, and amplification, the data is analyzed and calculated to determine the current fault state. If a certain frequency of ferromagnetic resonance occurs, the CPU immediately starts the harmonic elimination circuit (making the thyristor conductive) to quickly eliminate the ferromagnetic resonance under strong damping. After the elimination of ferromagnetic resonance, the CPU makes corresponding records, stores, and automatically alarms and displays relevant resonance information (including occurrence time, frequency, amplitude, etc.). If it is overvoltage or single-phase grounding, after the CPU makes a diagnosis, the device will display and alarm separately, and automatically record and store relevant fault information. Finally, the CPU returns to its initial state and continues to detect the open delta voltage.

6. Software composition of SBX-WXYH microcomputer harmonic elimination device
This device uses 80C196 assembly language to develop software, which mainly consists of monitoring program, floating-point operation library, diagnostic software, harmonic elimination, recording and other parts. The real-time monitoring program completes tasks such as voltage detection, sampling, diagnosis, harmonic elimination, clock, keyboard commands, and display. The simple block diagram is shown in Figure 1:

7. Hardware composition of the device
(1) Power Supply: This device uses a high-frequency switching power supply, which has strong anti-interference ability and allows for a large range of input voltage fluctuations. The output voltage is DC+5V, ± 12V
(2) Host part:
(3) The command and control center CPU of this device adopts the latest 16 bit microcontroller 80C196, which has the characteristics of fast computing speed, strong control capability, and safe and reliable operation. And it is equipped with an internal monitoring timer, which can free the system from crashes caused by software failures at any time, providing a guarantee for long-term safe and reliable operation;
(4) Program memory EPROM, used for storing instructions;
(5) Data storage RAM, used to store data calculation results, recall content, etc;
(6) Data acquisition part: Its function is to convert analog signals into digital signals for computer processing;
(7) Display section: Used as a clock under normal system conditions, it can display relevant fault information when the system malfunctions;
(8) Harmonic elimination control: Control the harmonic elimination circuit and activate high-power harmonic elimination components to quickly eliminate ferromagnetic resonances of various frequencies.

8. Installation of SBX-WXYH microcomputer harmonic elimination device
This device is installed on the PK screen or in the terminal box, and each device can be connected to 1-4 sections of busbars according to the user's selection. The schematic diagram of the terminal wiring after the device is as follows:
(1) 1PT * "and" 1PT "are respectively connected to the same name and non same name terminals of the first section of the busbar open delta voltage," 2PT * "and" 2PT "are respectively connected to the same name and non same name terminals of the second section of the busbar open delta voltage, and so on;
(2) The "power input" terminal can be connected to AC power or DC power without polarity. Its voltage range is 80-250V;
(3) The "external alarm" terminal is connected to the external alarm signal, and when there is no fault, it is a pair of normally open contacts. Close when the fault occurs and delay for about 1 minute until the fault disappears. Its contact capacity is DC 220V 0.5A. If the user needs, it can also be changed to voice alarm output, but it needs to be specified before ordering.
(4) Remote control port output:
(I) The serial port RS422/485 is a dual function port. When using RS485, only TXD+and RXD+need to be short circuited, and TXD - and RDX - need to be short circuited;
(II) Switching output: When ferromagnetic resonance occurs, 1-4 PT correspond to 1-4 sections of the busbar, and an alarm signal is output in a closed contact manner with a capacity of DC 24V/5A. The internal wiring is as follows:

9. Instructions for use
(1) Power supply: The indicator light is on when the power supply is normal. Otherwise, it should be checked whether the power supply or insurance is burnt out.
(2) Display section:
(I) The device enters the operating state immediately after being powered on, displaying the year, month, day, week, hour, minute, and second;
(II) When a single-phase grounding fault occurs in the system (such as the first section of the busbar or its associated line experiencing a single-phase grounding fault at 08:50:35 on March 8, 2003, with an open delta voltage of 60V and a current duration of 1 hour 08:08 seconds), the LCD screen displays the following content:
On March 8, 2003, at 08:50:35, busbar I was grounded at a voltage of approximately 60V for a duration of 01:08:08. Display time until the fault disappears;
(III) When the system experiences a resonance fault (such as the first section of the bus experiencing a 25Hz frequency at 8:46:06 on June 8, 2003)
When resonance occurs and the open triangle voltage is 70V, the LCD screen displays the following content:
On June 8, 2003 at 08:46:06, a 25Hz resonance occurred on busbar I, with an amplitude of approximately 70V. Display time until 1 minute after the fault disappears.
(3) Button section
(I) "Reset" button: When the device malfunctions, please use the "Reset" button to restart the device;
(II) "Remembrance" button: When a resonance fault occurs in the system, the screen will display the following prompt: "Please press the" Remembrance "button to view the fault information". At this time, pressing the "Remembrance" button can view the latest fault information. Continuing on time will result in a total of 20 resonance fault messages. The display form is the same as when resonance occurs;
(III) "Timing" button: To adjust the year, month, day, week, and clock, press the "Timing" button. When the data to be adjusted flashes, press the "Plus One" or "Minus One" button. After adjustment, please continue to press the "time calibration" button until all data stops flashing, thus completing one time calibration process.
10. Design specifications and ordering instructions
(1) The size of the opening on the screen of the chassis:
All models are 210 × 180 (width × height), and the depth of the chassis is 250mm
(2) The external dimensions of the chassis are as follows:
(3) Ordering precautions
If users need serial port function or language alarm function when ordering this product, please indicate it, otherwise it will be considered as not configured with the above functions. At the same time (refer to model 2 instructions), it is necessary to indicate the number of busbars carried.