HYGBN type intelligent transformer neutral grounding resistance cabinet

1. Overview of HYGBN type intelligent transformer neutral grounding resistance cabinet

In the 6-35kV AC power grid of our country's power system, the neutral point of the power grid has methods such as ungrounded, grounded via arc suppression coil, high resistance grounding, and low resistance grounding. In the power system (especially in the urban power supply system with cables as the main transmission line, the grounding capacitive current is large, which may make the occurrence of "intermittent" arc grounding overvoltage have a specific "critical" condition, resulting in arc grounding The generation of overvoltage. The application of neutral point resistance grounding forms a discharge channel for the energy (charge) in the grid-to-ground capacitance, and injects resistive current into the fault point, so that the ground fault current has a resistance-capacitance nature, reducing the The phase angle difference of the voltage reduces the reignition rate after the current at the fault point crosses zero and ends the arc, destroys the "critical" condition of arc overvoltage, and limits the overvoltage to less than 2.6 times the phase voltage. At the same time, it guarantees high-sensitivity ground fault protection. The equipment accurately determines and removes the primary and secondary faults of the feeder, thereby effectively protecting the normal operation of the system.

After the system is grounded by the resistance, it can limit the fault current to achieve the following protection functions:

1. Reduce the burning and melting accidents of faulty electrical equipment;

2. Reduce mechanical power when fault current passes through lines and equipment;

3. Reduce electrical vibration and damage to personnel caused by stray current in the ground return path;

4. Reduce the impact and flashover damage to the person, when someone happens to be at the point of failure;

5. Reduce the instantaneous line voltage drop caused by the occurrence and elimination of ground faults;

6. Ensure the control of instantaneous overvoltage.

The HYGBN type smart transformer neutral grounding resistance cabinet is used on the neutral point of the transformer of the 6~35kV AC power grid to realize that the neutral point of these power grids is grounded by resistance.

2. Product model description of HYGBN type intelligent transformer neutral grounding resistance cabinet

3. Product features of HYGBN type intelligent transformer neutral grounding resistance cabinet

1. The material of the resistance cabinet is imported aluminum-zinc plate, stainless steel plate or cold-rolled steel plate, beautiful appearance, strong corrosion resistance, and the protection level can reach I P56;

2. According to different usage conditions, the resistance cabinet is divided into indoor type and outdoor type. The cable entry method can adopt top entry and bottom exit and bottom entry and exit. When using top entry and bottom exit, the top of the cabinet is equipped with wall bushings, and the bottom of the cabinet is equipped with hanging bars for easy hoisting;

3. The resistance material is made of alloy materials. Stainless steel or nickel-chromium alloy materials have high conductivity and high temperature resistance. The maximum operating temperature can reach 1570℃. The temperature coefficient is small, the resistance value is stable, corrosion resistance, flameproof and explosion-proof, and high reliability. According to different customer requirements, our company can use imported resistance materials from British AB, American AVR, PGR or Canada 1-Gard to manufacture products.

4. HYGBN type smart transformer neutral grounding resistance cabinet is a standard product, which can be operated in parallel with resistance or reactance, which provides convenience for the gradual expansion of the power grid and the gradual reduction of grounding resistance;

5. When the transformer windings are delta-connected and the Z-winding grounding transformer needs to be installed independently, the neutral grounding resistance cabinet of the HYGBN smart transformer can be used with it.

6. In the intelligent control part, the traditional grounding resistance cabinet is only a pure hardware protection device. The resistance cabinet developed by our company according to market requirements has joined the intelligent control part. The hardware of the controller is based on an industrial-grade single-chip computer, and the software adopts a mixed programming of C language and assembly language, and the display part is a large-screen LCD Chinese characters. When the intelligent controller is normal, it can monitor the neutral point unbalanced current, the resistance piece and the temperature of the resistance cabinet. When a single-phase ground fault occurs, it can record the magnitude of the grounding line current, the grounding time, the temperature change of the resistance piece, the resistance cabinet and the number of grounding actions It also reserves a communication interface, which can transmit the information recorded in the detection to the main control room, so that the operating personnel can get complete relevant information in the first time.

Four, HYGBN type intelligent transformer neutral point grounding resistance cabinet usage conditions

1. Environment: Temperature: -40℃~+60℃, altitude: no more than 5000m, relative humidity: no more than 95% (25°C);

2. Installation site: The air should not contain chemical corrosive gas and steam, and no explosive dust;

3. Grid frequency: 48~52Hz (50Hz system), 58~62Hz (60Hz system);

4. Applicable to: indoor and outdoor, special conditions of use, please specify when ordering.

Five, HYGBN type intelligent transformer neutral point grounding resistance cabinet commonly used specifications, models and technical parameters

6. Appearance and installation

1. The schematic diagram of the equipment connection is shown in Figure 1 and Figure 2

                  Figure 1  Non-neutral system                   Figure 2  System with neutral point

2. The resistance cabinet can be fixed on concrete to keep the resistance level. The equipment enclosure should be reliably grounded through the cabinet foot grounding bolts. The external dimensions of the resistance cabinet are determined according to the specific parameters of the user.

For systems without neutral point                                                         For systems with neutral point

7.ordering instructions

Please inform the following parameters when ordering:

1. The rated voltage, resistance, current of the system, the way of incoming and outgoing wires;

2. The material, IP protection level, color and installation location of the resistance cabinet;

3. Current transformer ratio and current flow time;

4. If the cabinet needs to install an intelligent control system, our company will provide specific principles and wiring drawings.

8. Product acceptance

1. Check that the components of the resistor are intact and the accessories are complete, and disassemble the connecting copper bars between the electrical components in the resistance cabinet;

2. Measure the resistance of the resistance unit at room temperature. The change range should be within ±3% of the rated resistance. After the test is completed, restore the original wiring in the cabinet;

3. If the above inspection and experimental data are qualified, the product is a qualified product.

9. Transportation and storage

1. HYGBN intelligent transformer neutral grounding resistance cabinet is packed and transported, and it should be rainproof, placed gently, and upright to prevent collision;

2. Ensure that it is placed upright during storage. The ambient temperature of the storage location should generally be between -40°C and +60°C. The air should not contain chemically corrosive gases and vapors, and no explosive dust.