Product brief

Power transformers are one of the important components of the power system, and their safe and stable operation is an important guarantee for the safety of the power system. When a transformer is operating normally, its iron core and metal clamps must be reliably grounded at one point, otherwise the iron core will generate floating voltage to ground or multiple grounding points, causing heating faults and seriously threatening the safety of the transformer and the power grid. By monitoring the grounding current of the iron core, the presence of multiple grounding points in the transformer can be directly reflected. With the improvement of automation level, the use of online monitoring devices to monitor the grounding current of the transformer iron core has the advantages of good real-time and high accuracy, which can timely and accurately detect potential faults, avoid the waste of manpower and material resources caused by manual inspections, and the safety hazards caused by poor timeliness.

The YN-IM5000T transformer core grounding current online monitoring device can effectively monitor the core grounding current in real time, with the advantages of high accuracy, good stability, and strong functionality. It can be combined with the electrical equipment status evaluation system for status maintenance, evaluation, warning, and risk analysis, effectively improving the safe operation level of transformers.

Standard and norm

The online monitoring device for transformer core grounding current strictly follows the following national and industry standards, and some technical performance is superior to the requirements of the standards.

Q/GDW 535 General Technical Specification for Online Monitoring Device of Substation Equipment

Q/GDW 540.1 Inspection Specification for Online Monitoring Device of Substation Equipment Part 1 General Inspection Specification

Q/GDW 1894 Technical Specification for Online Monitoring Device for Grounding Current of Transformer Iron Core

Q/GDW 540.4 Inspection Specification for Online Monitoring Device of Substation Equipment Part 4: Grounding Current of Transformer Iron Core

Product composition principle

The online monitoring device for transformer core grounding current consists of a through type current transformer, signal acquisition and processing circuit, communication and display interface, etc. Its composition is shown in the following figure:

The grounding current of the transformer core is isolated and converted into a small signal through a through type current transformer. After signal conversion, filtering, amplification and other conditioning circuits, it is converted into a digital signal by an analog-to-digital converter. The microprocessor obtains the grounding current of the core through digital filtering and operation; The local display interface can display real-time grounding current, and has LED indication when it exceeds the alarm limit; The device can communicate in real-time with backend systems such as status monitoring systems through isolated RS485/CAN/GSM/GPRS communication interfaces (selected at the time of ordering). The device has a current limiting resistor switching control unit interface. When the current exceeds the set limit, the current limiting resistor (4-speed resistance) is automatically switched in step by step to reduce the grounding current as an emergency measure. When the current is below the limit, the current limiting resistor is automatically cut off.

Functional Features

The main functions of the transformer core grounding current online monitoring device are as follows:

Real time monitoring of transformer core grounding current;

Using a 5-digit digital tube to display real-time grounding current locally, with various status indicators for power supply, operation, communication, and alarm;

● It has multiple communication interfaces such as RS485/CAN/GSM/GPRS, which can achieve regular active data upload or request response upload; Can be connected to the background of the status monitoring system or run independently, and regularly send data to the operation and maintenance management personnel through SMS;

● Two levels of alarm limits (warning limit and alarm limit) can be set. When the current exceeds the warning limit, data is actively uploaded through the communication interface. When the alarm limit is exceeded, the device will emit a local light alarm and communicate the alarm;

Equipped with a current limiting resistor switching unit interface, it automatically limits and alarms the grounding current of the iron core;

The device has internal non-volatile storage space, and data is not lost when power is turned off;

The device has self diagnosis and self recovery functions, and alarms when the device is abnormal or communication is abnormal.

The online monitoring device for transformer core grounding current has stable performance and powerful functions, and has the following technical characteristics:

Accurate and reliable monitoring data

The device adopts specially designed current transformers, high-precision analog circuits, and advanced digital signal processing technology, with a wide measurement range (1mA~30A), high accuracy (± 1%), and good anti-interference performance.

● Flexible application configuration

The device has multiple communication interfaces, which can be configured to connect to the comprehensive monitoring system of electrical equipment, or can be independently configured to achieve monitoring through GSM SMS.

● Easy installation and maintenance

The device body and current transformer adopt a separate design, and a dedicated fixture allows the current transformer to be flexibly installed on the iron core grounding downline. The device body can be flexibly installed in different positions according to the on-site situation;

The device has a complete self checking function, which can timely determine the status of the device and give an alarm;

Installation and maintenance of all components, including sensors (bypass iron core grounding down conductors), can be carried out without affecting the operation of the transformer.

● Safe and reliable

The through type current transformer does not damage the grounding lead wire and has no impact on the safe operation of the transformer;

All components are produced according to industrial standards and have good resistance to electromagnetic shock and temperature fluctuations;

The device adopts a fully sealed design, which has functions such as anti-corrosion, windproof, dustproof, and electromagnetic interference prevention, and can adapt to harsh outdoor operating environments.

Product Application

The online monitoring device for transformer core grounding current can adapt to various environmental conditions for monitoring transformers. According to different application requirements, the device can be configured to be connected to the comprehensive status monitoring system of the substation equipment, independently monitored by GSM SMS, or combined with both for application. The application diagram is as follows:

TECHNICAL INDEX

Detecting parameters

communication interface

RS485 communication interface

○ Baud rate: 1200bps~19200bps, default 9600bps;

○ Isolation voltage 2500VRms;

Maximum number of nodes on the bus: 255;

● CAN communication interface (specified when ordering RS485/CAN)

○ Baud rate: 10kbps~500kbps, default 10kbps;

○ Isolation voltage 2500VRms;

Maximum number of nodes on the bus: 110;

GSM/GPRS interface (to be specified at the time of ordering)

○ Operating frequency band: 4 frequencies, 850MHz/900MHz/1800MHz/1900MHz;

GSM short messages in both Chinese and English, with 10 sending and receiving numbers set;

GPRS class 10, maximum downlink rate of 85.6 kbit/s, maximum uplink rate of 42.8 kbit/s, supports TCP/IP, FTP, HTTP protocols.

display

5-digit digital display current

Four LED indicators for power, operation, communication, and alarm

Working power supply

Voltage: 85~265VAC

Frequency: 47~63Hz

Power: ≤ 5W

protection grade

Device body: IP65 core current transformer: IP68

mechanical properties

Device body size: 252mm × 164mm × 71mm, weight: 1.8kg

Core Transformer:

Excluding fixtures: 114mm × 114mm × 52mm - aperture ø 55mm

Including installation fixtures: 140mm × 120mm × 110mm

Weight: 1.6kg

environmental condition

Working temperature:- 40℃～+65℃

Storage temperature:- 45℃～+80℃

Working humidity: ≤ 95%, no condensation

Atmospheric pressure: 80kPa~110kPa

Altitude: ≤ 2000m

Electromagnetic compatibility performance

Configuration and installation

Interface Description

The terminal definition is shown in the following figure:

Installation diagram

As shown in the above figure, the current transformer is directly installed on the iron core grounding lead wire using fixtures; The monitoring device body is installed in a suitable position by installing accessories according to different on-site conditions. Lead cables can be protected by waterproof corrugated pipes.

LED

Power indicator light: The device remains green and constantly on after being powered on.

Operation indicator light: green, indicating the system operation status. It goes off for 1 second during normal operation and lights up for 100ms.

Communication indicator light: indicates the operating status of GSM

(1) Orange: 1 second off, 100ms on - indicates that GSM is undergoing network access operation;

(2) Green: 3 seconds off, 100 ms on - indicates successful GSM network access;

(3) Red: 1 second off, 100 ms on - indicates GSM network access or search failure;

Alarm indicator light: When the current exceeds the warning value or alarm value, the red LED light will turn on.

PRODUCT MODEL

Type I - wired mode

Main Monitoring Parameters of Type I Transformer Core Grounding Current Online Monitoring Device

Type II - Wireless Mode

Using high-precision clamp current sensors to measure the grounding current of the iron core, achieving safe and reliable measurement.

Adopting LCD display, it can display clearly under sunlight.

Capable of waveform display and harmonic analysis, with accurate and reliable data measurement.

Built in calendar clock and non-volatile memory, capable of storing hundreds of test data.

Built in rechargeable power supply, capable of continuous operation for 8 hours.

The device has a Bluetooth communication interface, which can achieve data communication with tablets and laptops, and is equipped with upper level device management software.

Measurement range: 5mA～10A；

Accuracy: ± (2.5% x reading).