Rail transit refers to a type of transportation vehicle or system that requires operating vehicles to travel on a specific track.

The most typical rail transit is a railway system composed of traditional trains and standard railways. With the diversified development of train and railway technology, there are more and more types of rail transit, which are currently most commonly referred to as modern urban rail transit.

Urban rail transit is the backbone of urban public transportation, the main artery for passenger flow transportation, and the lifeline project of the city. He is a globally recognized "green transportation" with low energy consumption and less pollution, and is a golden key to solving "urban diseases", which is of great significance for achieving sustainable development of cities. So urban rail transit is the largest public welfare infrastructure in the history of urban construction, which will have a profound impact on the overall situation and development mode of the city.

Shenyang Siwo Electric Appliances has developed a series of distribution products specifically for the most widely used railway system in urban rail transit, to meet the special conditions and harsh environments of subway tunnel operation.

Common problems faced by dual power switch products in subway applications

● Wet and hot application environment　　

High humidity and high temperature application environments are typical real-world environments for subway vehicle and station sections

High temperature and humidity environments can cause moisture, condensation, and even water ingress or soaking in conventional dual power product controllers

Due to high temperature and humidity issues, the control system of conventional dual power products cannot convert or even malfunction, affecting the normal operation of the product and the normal power supply of subway operations

● Complex electromagnetic environment

High frequency DC, high-voltage DC, and various types of power supply are typical subway power and electromagnetic environments

The dual power control system is a weak current program control system designed and developed based on microcontroller technology, which is easily affected by complex electromagnetic interference

Electromagnetic interference can cause misoperation of conventional dual power control systems, including information misjudgment, drive misoperation, and incorrect state judgment, resulting in switch misconversion, non conversion, or frequent misoperation, which can have an accident level impact on subway operation power supply

● Possible frequent switching and overload

Real time and uninterrupted guarantee of subway power supply is the primary working principle of dual power supply products

Unreliable conversion performance, unable to meet the multiple and continuous conversion needs of subway operation power supply in emergency situations

Unreliable product performance can cause switch damage and power interruption in preventing sudden increases in high load current surges (fire loads, elevator overloads).

SIWOQ5 series products offer specialized solutions for subway applications

■ Three prevention process treatment

Adopting the three prevention process to treat controller systems that are easily affected by the environment

◆ Spraying waterproof and anti-static coatings on circuit boards and components themselves

◆ Welding pins are brushed with circuit board specific three anti solidification paint

◆ The installation of the controller (cabinet door type) is equipped with waterproof seals to ensure a high level of protection for external devices

Reliable protective measures can ensure that the dual power controller system can cope with adverse environmental issues such as high temperature, humidity, condensation, and water ingress in high temperature and humid environments, ensuring the normal operation of the dual power controller system

A good working environment for the controller system can ensure the normal operation of the dual power supply "core", providing a reliable prerequisite for dual power conversion

■ EMCdesign

Adopting multiple anti-interference designs, including input anti-interference, output anti-interference, and shielding ground anti-interference

The signal input circuit adopts a photoelectric isolation design to shield the interference input at the signal input end

◆ The working power supply adopts an isolation transformer combined with a decoupling circuit design, which shields interference signals from entering the working power supply end

◆ The output drive circuit adopts a relay isolated output design to prevent reverse input interference from the drive system

The overall circuit design adopts a shielding system design, and the core controller part adopts a shielding grounding design

High performance EMC design ensures stable and reliable operation of the dual power control system in complex power and electromagnetic environments of the subway. Reliable shielding measures can shield the negative effects caused by external electromagnetic interference

Protects against external interference, eliminates misoperation, and provides a stable and reliable controller system for dual power status judgment, signal acquisition, and drive output conversion.

■ Reliable usage category and contact conversion system

Support the usage category of AC-33A, with 10 times the rated operating current for making and breaking levels, and 10 times the cycle operation frequency of ordinary switch products (AC-33B/iB), and fast contact switching.

Faced with the high reliability power supply requirements of the subway, the high frequency conversion that may occur, the AC-33A usage category and fast conversion time brought by the electromagnetic drive system design can ensure the reliable guarantee of subway power supply and provide timely and reliable power supply for the subway supply

A comprehensive and independent contact system design is implemented, which achieves 10 times the rated operating current making and breaking capacity through contact silver plating process and independent multiple arc extinguishing grid system. It can stably and properly convert and handle sudden increase of large loads and current surges in subway power, ensuring timely and reliable continuous power supply.

The problems faced by fire and leakage protection products in subway applications

● Wet application environment

　　High humidity application environment is a typical real-world environment for subway vehicle and station sections

High humidity environments cause unstable fluctuations in electrical circuit leakage values, leading to false alarms and measurement failures of fixed leakage values

● Complex electromagnetic environment

　　High frequency DC, high-voltage DC, and various types of power supply are typical subway power and electromagnetic environments

The electrical fire monitoring product is a weak current program control system designed and developed based on microcontroller technology, which is easily affected by complex electromagnetic interference

Electromagnetic interference can cause hidden dangers in the leakage sampling and signal transmission of electrical fire monitors, resulting in inaccurate and false alarms in core measurements

● The impact of starting and stopping some electrical equipment on the overall system

　　The start and stop of some exhaust and air conditioning equipment in vehicles or sections will have a certain impact on the overall power supply system

High current and heavy load impacts can cause normal "leakage" inside cable joints or electrical switches, and high sensitivity detection may precisely cause false alarms

SIWOF series products offer specialized solutions for subway applications

■ Static compensation algorithm

The static compensation algorithm is an environmental compensation algorithm based on normal measurement algorithms. It provides an adjustable compensation coefficient algorithm for the actual application of the product in the field, which can cooperate with on-site debugging personnel to complete the alarm value setting of the entire system during on-site debugging, reducing false alarms caused by environmental factors.

Provide more reasonable leakage monitoring on site, achieve accurate detection, and reduce false alarms.

■ High performance EMC design

Adopting multiple anti-interference designs, including input anti-interference and shielding ground anti-interference

The measurement sampling circuit adopts a combination of closed-loop measurement and differential operation to improve sensitivity and reduce the impact of interference signals on the sampling signal

◆ The overall circuit design adopts a complete shielding grounding system design to ensure the accuracy and sensitivity of leakage measurement

The high-performance EMC design can ensure the accuracy of sampling and measurement, as well as the overall stable working state of the monitor, ensuring real-time and accurate leakage monitoring

■ Delayed anti false alarm processing

The delay time is adjustable, and a reasonable delay time range can be given based on the actual equipment situation and the actual "normal leakage" situation on site

Avoiding false alarms caused by external power switching and normal product leakage

Svo, we dedicate our efforts to achieving safe, reliable, and green rail transit.