GEDQ-ZCB-110 Neutral Point Complete Equipment

Overview

110kV and 220kV are the main voltage levels of the power supply network. Due to the high voltage, the neutral point is generally directly grounded. Due to the requirements of relay protection setting configuration and communication interference prevention, in order to limit single-phase short-circuit current, some transformers adopt a neutral point ungrounded method. In this operating mode, neutral point overvoltage can be caused by lightning strikes, single-phase grounding short circuit faults, etc. Moreover, transformers are mostly insulated in stages, so overvoltage poses a great threat to the insulation of the neutral point, and protective devices must be installed to prevent accidents from occurring.

The GEDQ-ZCB-110/220 series transformer Neutral point complete equipment is manufactured strictly in accordance with the relevant provisions of DL/T620-1997 "Overvoltage Protection and Insulation Coordination of AC Electrical Equipment" regarding the use of gap protection for transformer neutral points in 110kV/220 kV effectively grounded power grids, and designed in accordance with GB311.1-1997 "Insulation Coordination of High Voltage Transmission and Transformation Equipment" and the technical requirements for preventing grounding grids and overvoltage accidents in the "Eighteen Major Anti accident Measures for Power Grids" published by State Grid Corporation of China in June 2005. Suitable for neutral point overvoltage protection of ungrounded transformers in 110kV and 220kV effectively grounded power grids.

In order to ensure the reliable performance, easy installation, commissioning and operation, and simple and beautiful layout of the neutral point equipment in 110kV and 220kV substations, Juyi Electric has also launched a complete set of transformer neutral point equipment that integrates electrical equipment such as neutral point rod gap, gap Current Transformer, isolation switch, Lightning Arrester, Terminal box and installation bracket.

Users can choose a pure gap transformer neutral point overvoltage protection scheme, or they can choose a scheme that works in parallel with the gap and lightning arrester for coordinated protection. Lightning arresters and isolating switches can be flexibly assembled according to engineering needs. The operating mechanism of the isolation switch can be manually or electrically operated. The electrical and mechanical properties of the product are fully debugged and tested before leaving the factory, and can also be easily recalibrated on site.

Ambient condition                       

2.1 Suitable for indoor and outdoor use;

2.2 Environmental temperature: not lower than -50 ℃, not higher than+50 ℃;

2.3 Relative humidity: not exceeding 95% (25 ℃);

2.4 Altitude: not exceeding 2000m, customized according to actual conditions if exceeding 2000m.

Areas with an earthquake intensity of 7 degrees or below; Wind speed not exceeding 35m/s;

2.6 The air in the installation site should not contain chemical corrosive gases and vapors, and there should be no explosive dust.

2.7 Not applicable to non horizontal installation locations.

2.8 Grid frequency: 58-62Hz (60Hz system), 48-52Hz (50Hz system).

Performance characteristics

3.1 Direct connection between current transformer and rod gap;

3.2 The gap discharge voltage is stable, and the gap distance is easy to adjust;

3.3 Use stainless steel precision machining to ensure that the surface is not easily corroded;

3.4 The installation bracket adopts on-site welding free design technology, effectively solving the anti-corrosion problem of outdoor products;

3.5 Gap combination equipment base installation lifting ring, whole piece transportation and hoisting, on-site installation is fast and convenient;

3.6 Full range and specifications, suitable for different regions and users' requirements.

Technical Parameter

Instructions for the use of the main components of the transformer neutral point complete set equipment

GW13 series Neutral point isolation switch

1.Overview

The GW13 series neutral point isolation switch is a single AC 50Hz outdoor high-voltage electrical appliance used to open and close the neutral point of the transformer and the grounding connection line under voltage and no-load conditions, thereby realizing the free switching between the grounded or ungrounded operation modes of the transformer neutral point.

The GW13 series neutral point isolation switch can be equipped with manual or electric operating mechanisms according to user requirements.

2. Main structure of the product

2.1 GW13 neutral point isolation switch consists of a base, post insulators, conductive bars, contacts, terminal blocks, etc.

2.2 There are contacts and connection plates on the upper part of the post insulator, and a crank arm and connecting rod on the lower part. The operating mechanism drives the isolation knife switch to perform opening and closing movements through output crank arms, connecting rods, bearing crank arms, etc.

2.3 The contacts of the isolation switch consist of three pairs of contact fingers, contact finger springs, and contact finger seats.

3. Installation

3.1 Push the isolation switch body to the closing position by hand, then install the electric (or manual) operating mechanism in place and manually move the operating mechanism to the closing position. Connect the operating link according to the actual required length to ensure that the switch blade can be reliably opened and closed when the mechanism is in the opening and closing position. Finally, tighten the fasteners at the joint.

3.2 The measurement of the main circuit resistance of the isolation switch should be within the range shown in the following table:

After the measurement is qualified, industrial Vaseline oil should be applied to the contact part

5. Usage and maintenance

This isolation switch can only be operated when there is no load on the circuit. Switches should be regularly inspected (about 1-2 years), and in case of serious malfunctions, they should be repaired immediately after the malfunction.

5.1 Clean the surface dirt of conductive parts and post insulators, clean the connection plane and contact surface between the terminal and busbar, and apply industrial Vaseline.

5.2 Check if fasteners such as taper pins and bolts are loose.

5.3 Check if the operating mechanism is functioning properly.

6. Packaging, transportation, and storage

6.1 The packaging box of the product should be marked and not allowed to be overturned.

6.2 After the product arrives, please conduct timely inspection. If any problems are found, please contact our company in a timely manner for analysis and handling.

6.3 After the product is opened, if it is not installed immediately or needs to be stored for a long time, it must be stored in a dry and sheltered place.

YH1.5W series neutral point lightning arrester

• Model Description

Y1.5W-144/320 is a composite sheathed gapless metal oxide lightning arrester for neutral point protection of 220 kV transformers, with a rated voltage of 144 kV and a residual voltage of 320 kV at a nominal discharge current of 1.5 kA.

• Main purpose

The gapless metal oxide surge arrester for rated voltage 6-220 kV AC systems is an important protective device used to protect power transmission and transformation equipment from atmospheric and operational overvoltage damage.

• Performance characteristics

This series of lightning arresters has excellent steep wave response characteristics, no freewheeling, low operating residual voltage, and low discharge dispersion. It has the ability to absorb various lightning and operating overvoltages. Self standing lightning arresters with voltage levels of 35 kV and above are equipped with pressure release devices, which can effectively prevent ceramic bushing breakage caused by internal arc impact. The lightning arrester uses rubber as the sealing material to ensure the reliability of the seal. The technical performance of the product meets the requirements of GB11032-2000 "AC gapless metal oxide lightning arrester" and IEC60099-1991. The main electrical characteristics of the product are shown in the attached table. The attached table shows the typical product technical parameters of our company. If users have different requirements, we can design and manufacture according to their needs.

• Installation requirements

When installing suspended products, fix them on the bracket or crossbar with installation clips.

When installing a self-supporting product, first fix the lightning arrester on the foundation (see the attached diagram for installation dimensions), then install the lightning arrester components in sequence, connect the upper part to the high-voltage wire, and ground the lower base. It can also be grounded through a discharge counter.

• User Notice

1. Before the newly installed lightning arrester is put into operation and before the thunderstorm season every year, the following preventive test items should be carried out:

a、 DC reference voltage test

Apply a direct current voltage (DC voltage ripple coefficient not greater than ± 1.5%) at both ends of the lightning arrester. After the current passing through the lightning arrester stabilizes at 1mA, the voltage value U1mA should be greater than the specified value in the table.

b、 DC leakage current test

After applying a DC voltage of 0.75U1mA at both ends of the lightning arrester, the leakage current level flowing through the lightning arrester or component is greater than 50uA.

3. During transportation and storage, self-supporting lightning arresters should be placed vertically. Users are not allowed to dismantle the lightning arrester at will to prevent its failure. If the user has any requirements, we can negotiate the supply.