1 UPS's role and function
The role of UPS as a protective power supply is critical. When the mains supply is interrupted, the UPS immediately supplies power to the load by means of inverter conversion. When the mains supply is normal, the UPS is equivalent to an AC voltage regulator, eliminating the effects of power surges, transient high voltages, transient low voltages, power supply noise and frequency offsets.
2 UPS use and maintenance issues
During the process of using UPS, it is sometimes found that the UPS does not function as an uninterrupted power supply when the mains is powered off. The UPS battery fails or the discharge capacity drops significantly in a short period of time. During normal charging, there is a fever and the float charge flow is obvious. Increased, these issues affect the user's use of the load. The causes of these problems involve the quality of the UPS itself, the quality of the UPS installation, and the quality of the user. This requires selecting a UPS that meets the requirements for use and properly installing the UPS. In terms of user quality, it is mainly determined by the user's specific use of environmental quality, power supply quality and daily maintenance quality.
(1) Since the general load has an inrush current at the moment of starting, an excessive current may shorten the service life or even cause damage. Generally, the UPS should be powered first, so that it is in the bypass working state, and then the load is turned on one by one to avoid the impact of the load current on the UPS, so that the service life of the UPS can be prolonged. The shutdown sequence is to first turn off the load one by one, then turn off the UPS, the UPS is in bypass operation and the charger continues to charge the battery pack.
(2) The UPS system requires a small amount of power according to the requirements of use, and should not be used at full capacity. Do not use according to the rated power of the UPS. Do not think that the empty interface should not be idle and connect other electrical appliances. The long-term full load state will directly affect the UPS life. Under normal circumstances, the load of the online UPS should be controlled at 70% to 80%, while the load of the backup UPS should be controlled at 60% to 70%. At the same time, excessive light load is not good, although not as serious as overload.
(3) The battery components of the UPS are built-in and external. The built-in battery is relatively convenient to use. There is no problem with the connection between the UPS main unit and the battery pack. For external batteries, the UPS must pay attention to the problem of the connection between the main unit and the battery pack. First of all, the battery pack must be connected according to the positive and negative polarity, and the voltage of the battery pack should be checked. The voltage level and the UPS host requirements are met, and the connection is correct. Next, turn on the UPS main unit and measure the charging voltage of the UPS main unit. The voltage value is correct. Finally, connect the positive and negative polarity of the battery pack to the UPS main unit. In the application, there is often an accident that the battery connection line is damaged or the UPS charging circuit is damaged due to a wrong connection of the UPS battery pack.
(4) The daily maintenance work of the UPS mainframe is mainly dustproof and regular dust removal. The second is to check whether the connectors and inserts are loose or not in contact during dust removal.
(5) When the UPS battery fails, you should first find out the cause. Distinguish whether the fault source is the load or the UPS power supply system; whether it is a host or a battery pack. Although the UPS main unit has a fault self-test function, it is opposite to the point. Although it is convenient to replace the parts, it is still necessary to do a lot of analysis and testing work to repair the fault point.
(6) For the failure of the host to breakdown, fuse or burn the device, be sure to find out the cause and eliminate the fault before restarting, otherwise the same fault will occur.
(7) For long-term unused UPS, before re-commissioning, it is best to let the UPS use the charging circuit inside the machine to charge the battery for 10~12h. For the backup UPS users, if the UPS is working in the backup mode for a long time, it is recommended to leave the UPS in the inverter for at least 2~3 minutes every other month to activate the battery.
3 The main reason affecting the battery life of UPS system
(1) The ambient temperature is too high
For every 10 °C increase in ambient temperature, battery life is reduced by 50%. Especially in the UPS system, the number of batteries is large and the concentration is concentrated, so it is important to maintain an appropriate ambient temperature. The general UPS system has an automatic temperature compensation function, that is, for every 1 °C rise in temperature (standard temperature 25 °C), the float voltage should be lowered by 5 mV/monomer, and vice versa.
(2) The charging voltage is too high or too low
When the float voltage is too high, the grid corrosion is accelerated and the water loss is increased. When the float voltage is too low, the battery is in a state of charge and unsaturation for a long time, forming "sulfation".
4 UPS system battery maintenance method
(1) Clean the surface of the battery regularly, keep the ambient temperature at 20 °C ~ 25 °C and good ventilation.
(2) Regular inspection, including: float voltage of monomer and battery; loose connection; battery case and pole temperature; acid and acid mist overflow around pole and safety valve; Batteries with years of life or end-of-life should be given more attention. It can be judged by parameters such as float voltage and internal resistance of the battery, but the most direct and accurate method is to test by discharge, and the depth of discharge does not exceed 80% in principle.
(3) Regular charge and discharge. The float voltage and discharge voltage of the battery in the UPS have been debugged to the rated value at the factory, and the discharge current increases with the increase of the load. The load should be adjusted reasonably during use. It should be completely discharged every 2 to 3 months. The length of discharge can be determined according to the capacity of the battery and the load. After a full load discharge is completed, recharge for more than 8 hours.
(4) The battery needs regular maintenance. Usually, the total voltage of the battery pack should be measured once every 3 to 6 months. If the voltage exceeds 1V, you should use a balanced constant voltage current limit (0.5A) to charge. If it does not work, you can only replace the battery. If the local long-term power is not lost, the power supply must be interrupted periodically (three months) to discharge the UPS with load.
(5) The UPS mainframe does not require high ambient temperature. It can work normally from 5 °C to 40 °C, but it is required to be clean indoors. Otherwise, dust and moisture will cause the main machine to malfunction.
(6) The circuit parameters set in the main unit cannot be changed at will during use. Especially for the parameters of the battery pack, otherwise it will directly affect its service life, but as the ambient temperature changes, the float voltage should be adjusted accordingly.
(7) In any case, short-circuit or deep discharge of the battery should be prevented because the cycle life of the battery is related to the depth of discharge. The deeper the discharge depth, the shorter the cycle life. In the capacity test or during the discharge repair, it is usually sufficient to discharge 30% to 50% of the rated capacity.
(8) The power of the high-power UPS battery pack is very high, and there is a danger of electric shock. Therefore, the safety connection should be ensured when loading and unloading the conductive connecting strip and output line, and the tool should adopt insulation measures. Whether in the floating charge working state or in the charging and discharging maintenance test state, it is necessary to ensure that the voltage and current meet the specified requirements. Excessive voltage or current may cause the battery to lose control or lose water. If the voltage and current are too small, the battery will lose power. This will affect the service life of the battery. The former has a greater impact.
Even the best equipment has a long life, and various types of faults can occur. However, good maintenance can prolong life and reduce the occurrence of faults. In short, you need to maintain more when using UPS. This will avoid many human factors and increase UPS. The service life.
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