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I. What is UPS

UPS is short for Uninterruptible Power Supply, which is a system equipment that connects batteries (mostly lead-acid maintenance-free batteries) with the host, and converts direct current (DC) into mains power (AC ) through modular circuits of the host inverter.

Three basic functions of UPS: voltage regulation, filtering, uninterrupted power suply. It is mainly used to provide stable and uninterrupted power supply to computer network system or other power electronic equipment such as solenoid valves, pressure transmitters, etc.

When the mains input is normal, UPS will stabilize the main electric and supply it to the load. At this time UPS is an AC voltage stabilizer, and it also charges the battery; once the mains AC input is abnormal, such as overvoltage, under voltage, power failure, abnormal frequency, UPS will immediately supply 220V AC power to the load by switching the DC power of the battery to the load. Therefore , the load can maintain normal operation and protect the software and hardware of the load from damage. Supplying time depends on the battery capacity of the UPS and the power consumption of the load equipment.

II. Why is UPS easy to catch fire ?

UPS provides an important guarantee for the power of the computer room. UPS power system is also easy to catch fire caused by many reasons . In the event of a fire in the UPS power supply system, a large amount of toxic gas will be produced, which is extremely difficult to put out, and the financial loss caused by the fire is also difficult to estimate.

There are the belows reasons caused by UPS battery burned.

1. A routine preventive maintenance of batteries never have not been taken . There are battery problems have not been taken seriously, such as battery electrolyte dry, Battery thermal runaway, early capacity loss, internal short circuit, Defective battery housing, failure safety valve, battery swollen up and pole corrosion . That will caused by burned batteries and even there is a large-loss fire.

Valve-regulated sealed lead-acid (VRLA) batteries are the main accessories of medium and high power UPS. VRLA is commonly known as a maintenance-free battery, which is generally considered to be maintenance-free.

Many people think that this kind of battery does not need maintenance. After installing the battery, it has never been maintained again. UPS battery is greatly affected by the surrounding working environment.

If the temperature is too high, it will cause problems such as deformation of the battery casing, leakage of electrolyte, insufficient capacity, and uneven voltage at the battery terminals, which can easily cause fire.

1) The leakage of UPS battery electrolyte causes the imbalance between cell battery , and the breakdown phenomenon occurs during the charging and discharging process, resulting in a fire.

There are many electronic devices in the computer room. If the temperature is too high and the air is dry, a lot of static electricity will be generated. UPS battery is most likely to catch fire due to the long-term influence of high temperature, deformation of the casing, leakage of electrolyte, and static electricity.

The capacity of the whole group of batteries is based on the capacity value of the battery in the worst condition, not the average value or the rated value (initial value), when the actual capacity of the battery drops below 90% of its own rated capacity , the battery will enter a recession period. When the battery capacity drops below 80% of the original, the battery will enter a rapid recession state. The recession period is very short. At this time, the battery pack already has a great hidden danger of accidents. During the charging and discharging process Breakdown is prone to occur.

2) The failure of the battery gas regulating valve leads to the occurrence of fire

The failure of the gas regulating valve of the battery leads to the occurrence of fire. If the gas regulating valve in the valve-controlled sealed lead-acid battery fails, the gas generated during the internal charging process of the battery (when the charging reaches a certain voltage, generally above 2.30 V / single cell) ), oxygen is released from the positive electrode of the battery, and hydrogen is released from the negative electrode, which cannot be discharged in time. When the internal pressure of the battery exceeds the pressure that the ABS plastic shell can bear, it will cause the ABS plastic cover of the battery shell to bulge and rupture or explode and cause a fire. occur.

3)Corrosion of the internal terminals of the battery, the connecting pieces of the same pole and the electrode joints lead to a short circuit of the plates and a fire.

The corrosion of the electrode joints inside the UPS battery and the short circuit of the plates are all due to the accumulation of too much dust on the UPS battery. The dust itself contains various unknown objects, which will cause the joints of electronic equipment to corrode and short-circuit.

When the battery pack is charged and discharged, the temperature at the contact point rises sharply, resulting in a short circuit of the terminal (connecting piece) and the burning of the casing, resulting in a fire.

4) UPS batteries have strict requirements on the working environment, such as temperature, humidity, etc. Changes in environmental factors can also lead to battery failures and fires.

Experiments have shown that based on the operating temperature of the UPS battery at 25°C, the service life will decrease by 50% for every 1°C increase. Therefore, it is very important to dust the UPS battery in time and maintain good heat dissipation!

2. Fire risk of UPS system connecting bus line

The backup battery bank of large and medium-sized UPS power supply system is usually composed of dozens or even hundreds of batteries in series and parallel. According to fire cases, unreasonable wiring design between battery banks, especially irregular construction, is an important cause of fire accidents.

(1) Faults such as overloading, grounding, and local contact resistance are too large, which can cause the cable to overheat and the insulation layer to melt and burn. Due to the high energy of the DC power supply, once a problem occurs and is not discovered in time, a fire will inevitably occur.

(2) When leakage or grounding fault occurs in the line, the leakage current can easily ignite the surrounding combustibles and cause a fire.

(3) In the event of a short circuit, the high temperature effect of the strong arc can rapidly melt, vaporize or ignite the surrounding combustibles by the local metal of the copper wire, and aggravate the spread of the fire. The hydrogen leaked further, causing the equipment to burn on a larger scale; in addition, because the cable lines had been ignited, the system cables were constantly jumping and short-circuiting, resulting in the further spread of the fire.

III. How to extend your UPS battery life ?

1. Perform regular battery maintenance

Battery is main accessory of UPS power . It is essential for routine maintenance of batteries. Battery capacity specification clearly shows the discharge time of battery .

1) Battery Discharge Charge Periodically

The mains power failure rarely occurs in the dailylife , the battery will be in a floating charge state for a long time, which will lead to a decrease in battery activity over time, accelerated aging and shortened service life. By checking the battery impedance parameters, you can ensure that the healty statement of cell battery. Some types such as battery internal resistance tester KV-5190 is appliable .

For UPS batteries string, the effective methods of measuring an accurate capaity of battery is to perform a discharge test for identify the batteries fail or good. The battery should be fully charged and discharged for one time every 2-3 months, and the battery charging and discharging time can be determined according to the capacity and load of the rechargeable battery. After the battery is fully charged and discharged, the battery should be charged for more than 8 hours according to regulations. Type KVF-3900 battery charge discharge tester can conduct charge and discharge test for UPS batteries.

2) Keep your batteries in correct operating temperature

Comprehensive consideration, UPS power supply circuit is generally adopts maintenance-free lead-acid batteries, and the service life is generally about 5 years. The operating temperature of the battery is 20~25°C. Once it exceeds 25°C, the battery life will be reduced by half for every 10°C increase

2. Install Battery Monitor Test System

Battery Monitor Test System can monitor the current, voltage, capacity, internal resistance, temperature and other parameters in real time, . That can give a timely alarm to each battery failure. 

Battery monitor test system can monitor the battery state in 7*24

3. Regularly remove dust, and remove static electricity

Regularly dusting the UPS battery pack and eliminating static electricity is not only to remove dust and keep the equipment in good heat dissipation, but to conduct a “physical examination” of the entire UPS to eliminate potential safety hazards.