The power system is an essential subsystem of a dedicated communication system. Once the communication power supply fails and stops supplying power, it will inevitably cause interruptions in all communication subsystems. Therefore, the safety and reliability of the power supply system are extremely important. It not only requires the external AC power supply to be very reliable, but also requires the communication power supply system to be very reliable. In addition, it requires the system to automatically start the backup battery to provide uninterrupted and transient power guarantee for the system equipment when the external AC power supply is cut off. However, due to long-term use and frequent charging and discharging, subway communication batteries often experience aging or damage, and therefore need to be replaced regularly. This article mainly explores the replacement of subway communication power system batteries, providing some reference for the replacement of batteries in various subway specialties in the future.

Keywords: subway; Communication system; Power supply system; Battery replacement.

introduction:

According to the "Railway Communication Maintenance Regulations of China Railway Corporation (TG/TX106-2014)", the design service life of communication batteries is 5 years, and the "YD-T-1970.10-2009 Technical Requirements for Maintenance of Power Supply Systems of Communication Bureaus (Stations)" Part 1 specifies the effective service life of equipment under normal use and maintenance conditions. The service life of batteries above 6V is 6 years, and the industry standard internal resistance of 100AH batteries is 4.5 milliohms, and the industry standard internal resistance of 160AH batteries is 4.0 milliohms. Due to the relatively short service life of equipment in various railway systems, subway specialties should prioritize the monitoring of batteries for 7 years in order to maximize resource utilization and save maintenance costs during battery overhaul work, and conduct a thorough evaluation.

1、 Implementation Plan for Battery Pack Replacement

（1） Preparation before construction

1. Personnel configuration

(1) Technical engineer;  

(2) On site manager;

2. Equipment configuration

(1) Specialized instruments;

(2) Protective tools;

(3) Special tools;  

3. Data backup

(1) Registration and backup of construction plans, personnel information, and qualification certificates;

(2) Backup device data records to prevent data loss caused by operational errors or system failures during construction;

（2） Equipment positioning reference requirements:

1. Ground requirements:

Choose a horizontal hard ground for equipment placement, and it is recommended to install anti-static activity flooring to ensure good stability and firmness. If necessary, increase floor support to meet the load-bearing requirements of the equipment floor;

2. Environmental requirements:

A、 Temperature: 0 ℃~40 ℃. Should not include or be close to heat sources to ensure the specified environmental conditions of the equipment;

B、 Humidity: 20%~60%;

3. Heat dissipation requirements:

Keep a distance of at least 500mm between the UPS and its supporting equipment and walls or adjacent equipment. Do not cover the rear, side, or bottom air inlet of the equipment with objects to avoid obstructing the exhaust performance of the UPS and supporting equipment's fan exhaust holes.

2、 Implement the dismantling of the original battery

1. Before dismantling the battery, make relevant registration records for the UPS host, old battery pack, battery monitoring device and other equipment, especially for the placement of each layer of battery and the wiring of the battery monitoring device. Mark and draw the connection diagram. Ensure that the effect of dismantling the battery pack remains consistent with the original situation;

2. Ensure that the UPS host is disconnected and the connection switch between the UPS host and the battery pack is disconnected when the mains power is stable, to ensure the safety of personnel when removing the battery;

3. Dismantle the original battery pack, and the technical engineer and personnel responsible for the dismantling of the battery are responsible for the dismantling work. Relevant assistance personnel are responsible for the handling of new and old batteries;

After dismantling the old battery, transport it to the designated location and install the new battery pack at the same time.

3、 Implement new battery installation

In order to ensure that the UPS power system is always in a backup power protection state during the battery replacement process, install each removed set of batteries, place the new batteries on the battery rack, and adjust their placement position and direction on the battery rack to the best. When installing a new battery, the original battery monitoring connection wire should be reconnected. After connecting a set of batteries, check if the connection wires of the battery terminals are secure; Check if the total voltage of the battery pack is normal, and ensure that the positive and negative terminals of the battery are connected correctly;

2. After the battery replacement work is completed, check whether each screw is tightened, designate a dedicated person for re inspection, re inspection, and final inspection to ensure that each battery screw is in a tightened state; Use a multimeter to check the total voltage of the battery pack, as well as the wiring of the positive and negative terminals and neutral wire of the battery pack;

3. After ensuring that both the battery pack and the UPS host are functioning properly, close the switch of the battery pack to restore the normal operation of the UPS uninterruptible power supply system. Then, check the working voltage, current, charging voltage, working status, etc. of the UPS and make records;

After the UPS host is debugged normally, disconnect the input power switch of the UPS host, simulate a mains power failure interruption, and test whether the UPS system can switch from mains power to backup power supply of the battery pack to ensure the normal operation of the equipment in the computer room cabinet;

4、 Inspection work after battery replacement

Mainly inspect the following aspects:

1. The on-site environment of the UPS power room, the placement and connection of the batteries;

2. Technical engineers debug and set the battery time parameters of the UPS host to ensure that there will be no false alarms during the normal lifespan of the battery;

3. Check the input and output voltage and current of the UPS host; Charging voltage; Ensure that all testing data meets the required parameter range, including work status, and keep records;

4. Confirm that the UPS host and battery are operating normally, and then conduct a mains power outage test to check the automatic switching of the battery and the battery power supply time.

Through this battery replacement work, the safety and reliability of the UPS system have been improved, mainly reflected in the following aspects:

I replaced the old battery to avoid potential hazards and reduce the failure rate of UPS hosts caused by battery issues.

When the mains power is interrupted, there will be no power outage of the UPS host, and the high performance of the new battery ensures the power supply time of the backup battery of the UPS system.

A good battery pack ensures the normal operation and backup time of the UPS system, ensuring the safe operation of important equipment such as the computer room.

5、 Connection between battery pack and UPS

1. Open the protective board outside the wiring terminals behind the UPS, ensure that the number of wiring terminals and screws are complete, and disconnect the battery switch;

2. Count and confirm the cables connecting the battery pack to the UPS, and mark and wrap the cables for protection;

3. After assembly, the battery pack in the battery rack is already charged. Connect the UPS end of the battery pack and UPS connection cable first, and then connect the reserved positive, zero, and negative terminals of the battery pack in sequence. The wiring sequence cannot be changed, and the positive, zero, and negative polarity of the wiring cannot be incorrect;

4. Connect the wires according to the drawing and use torque tools to fix the screws;

5. Attention:

(1) Pay attention to the firmness and reliability of the torque between the contact points of the wiring terminals.

(2) If concealed cable laying is required (such as underground wiring, trunking wiring, etc.), cable laying should be carried out in advance.

(3) After concealed installation of connecting cables, pay attention to necessary protection for their bends and contacts.

6、 Battery acceptance

1. Inspection items

(1) The battery rack should be firm and reliable, and should not be dented or deformed

(2) The battery rack is undamaged and rust free;

(3) Check the installation position of the battery: arranged neatly and in accordance with the design requirements.

(4) Check that the terminal connections of the battery pack are not loose and the wiring is not loose;

(5) Check the appearance of the battery for damage, deformation, moisture, oxidation, mold, and leakage;

(6) Battery structure: Whether the positive and negative poles of the battery are easy to connect and have clear markings, and whether the battery terminals are connected with bolts and nuts;

(7) Check if the positive and negative polarities of the battery pack are connected correctly.

(8) Check for flammable, explosive, corrosive or other debris in the battery room.

(9) Check whether the battery manufacturer and model meet the bidding requirements.

2. Testing items

(1) Environmental temperature detection: can be used normally under the conditions of -35 ℃~55 ℃, meeting the design requirements;

(2) Horizontal deviation detection: no more than 3mm per meter and no more than 10mm in total length;

(3) Battery connection strip: Whether the torque of the fastening screws of the connection strip meets the design requirements, whether the voltage of the connection strip is less than 10mV, and whether the connection strip is coated with Vaseline, conductive paste or flame-retardant insulation cover;

(4) Capacity retention rate detection: whether the capacity retention rate of the battery is not less than 97% after being left idle for 28 days;

(5) Battery internal resistance detection: whether the internal resistance of each type of battery meets the design requirements;

(6) Charge and discharge test: Record battery charge and discharge test data, observe whether the charge and discharge conditions are normal.

7、 Conclusion

The research on battery replacement for subway communication power system is of great significance for ensuring the safe and stable operation of the communication system. This article proposes a series of specific operating procedures and suggestions for battery replacement, hoping to provide reference for the replacement of batteries in various specialties of subway.