Uninterruptible Power Supply

UPS backup power supply (uninterruptible power supply) is not only directly used for computers, but also for equipment equipped with computers (such as medical CT, supply station instruments, etc.), radar stations, military communication systems, programmable telephone systems, surgical operating rooms, etc., UPS is used instead of generators for backup power supply.

UPS backup power supply (uninterruptible power supply) is a protective equipment, and effective maintenance can ensure the normal operation of the equipment and reduce organizational losses.

1、 Regular battery maintenance:

After a certain period of use, batteries should be regularly inspected, such as observing whether their appearance is abnormal, measuring whether the voltage of each battery is average, etc; If there is no power outage for a long time, the battery will remain in a charging state, which will reduce its activity. Therefore, even if there is no power outage, UPS prices need to undergo regular discharge tests to keep the battery active. The discharge test can generally be conducted once every three months. The method is to load the UPS, preferably at 50% or more, and then disconnect the mains power to place the UPS in a battery discharge state. The discharge duration usually ranges from a few minutes to several tens of minutes depending on the battery capacity. After discharge, restore the mains power supply and continue to charge the battery.

2、 Inspection of battery:

Batteries will experience self discharge, and if left unused for a long time, it will cause energy loss. Therefore, regular charging and discharging are necessary. Engineers can judge the quality of a battery by measuring its open circuit voltage. Taking a 12V battery as an example, if the open circuit voltage is higher than 12.5V, it means that the battery still has more than 80% energy stored. If the open circuit voltage is lower than 12.5V, it should be recharged immediately. If the open circuit voltage is lower than 12V, it means that the battery has less than 20% energy stored and is at risk of being unusable. Maintenance free batteries, due to the use of an absorbent electrolyte system, do not produce any gas during normal use. However, if the user uses the battery improperly and causes overcharging, gas will be generated. At this time, the internal pressure of the battery will increase, which will push open the pressure valve on the battery. In severe cases, it may cause the battery to swell, deform, leak or even rupture. These phenomena can be judged from the appearance. If the above situation is found, the battery should be replaced immediately.

3、 How to maintain the battery and what is its normal lifespan?

1). the battery should be charged and discharged every 3-6 months, and the charging time of the standard machine should not be less than 10 hours after discharge.

2). UPS backup power supply (uninterruptible power supply) should be charged every 3-6 months if it is not in use for a long time.

3). The battery usage environment requires a temperature between 0 ℃ and 40 ℃, avoiding direct sunlight and keeping it clean.

4). Under normal use at room temperature, the float charging lifespan of Panasonic sealed maintenance free lead-acid batteries is 3-5 years.

4、 Common troubleshooting questions during the maintenance process of UPS backup power supply (uninterruptible power supply):

UPS backup power supply (uninterruptible power supply) plays an important role in protecting your data and machine equipment from damage. Therefore, the proper use and maintenance of UPS is quite important. Many users are limited to the precautions in the product manual. 5、 Company engineer discusses in detail the maintenance experience of UPS backup power supply (uninterruptible power supply):

1). A pair of power amplifier transistors in the inverter power stage were damaged. After replacing them with transistors of the same model, they burned out again after running for a period of time due to excessive current. The reasons for excessive current include:

——Overcurrent protection failure. When overcurrent occurs in the output of the inverter, the overcurrent protection circuit does not work;

——Pulse width modulation (PWM) component failure, resulting in asymmetric output of two complementary waveforms, with one having a long conduction time and the other having a short conduction time, causing unbalanced operation of both arms, and even simultaneous conduction of both arms, causing damage to both tubes;

——The parameters of the power tubes vary greatly, and even if a symmetrical waveform is input, the output will be asymmetric. This waveform, when passed through the output transformer, causes magnetic bias, that is, magnetic flux balance, which accumulates and saturates the transformer, causing a sudden increase in current and burning out the power tubes. One tube burns out, and the other also burns out.

2). The battery voltage is low, but after charging for more than ten hours, the battery voltage still cannot be charged.

Fault analysis: Judging from the phenomenon, it is a battery or charging circuit fault, which can be checked according to the following steps:

——Check if the input and output voltages of the charging circuit are normal;

——If the charging circuit input is normal but the output is abnormal, disconnect the battery

If it is still not normal after retesting, it is a charging circuit fault;

——If both the input and output of the charging circuit are normal after disconnecting the battery, it indicates that the battery has been damaged due to long-term uncharged, overdischarged, or expired.

3).When there is mains power, the UPS output is normal, but when there is no mains power, the buzzer beeps continuously and there is no output.

Fault analysis: Based on the phenomenon, it can be determined that there is a partial fault in the battery and inverter. The following procedure can be followed for inspection: (Related content: UPS price)

——Check the battery voltage to see if the battery is undercharged. If the battery is undercharged, check whether it is a fault with the battery itself or the charging circuit.

——If the working voltage of the battery is normal, check whether the inverter drive circuit is working properly. If the output of the drive circuit is normal, it indicates that the inverter is damaged.

——If the inverter drive circuit is not working properly, check whether the waveform generation circuit has PWM control signal output. If there is control signal output, it indicates that the fault is in the inverter drive circuit.

——If there is no PWM control signal output from the waveform generation circuit, check whether its output is blocked due to the operation of the protection circuit. If so, identify the cause of the protection;

——If the protection circuit is not working and the operating voltage is normal, and the waveform generation circuit has no PWM waveform output, it indicates that the waveform generation circuit is damaged.

The above troubleshooting sequence can also be reversed, sometimes it can detect faults faster.

4).After the UPS is turned on, there is no display on the panel and the UPS does not work.

Fault analysis: Judging from the fault phenomenon, the fault lies in the mains input, battery, mains detection part, and battery voltage detection circuit:

——Check if the fuse of the mains input is burnt out;

——If the fuse of the mains input is intact, check if the battery fuse is burnt out, because some UPS will turn off all outputs and displays of the UPS when it cannot detect the battery voltage during self inspection;

——If the battery insurance is intact, check if the mains power detection circuit is working properly. If the mains power detection circuit is not working properly and the UPS does not have the function of starting without mains power, the UPS will also shut down all outputs and displays.

——If the city detection circuit is working properly, then check if the battery voltage detection circuit is normal.

5、 Operation specifications for UPS backup power supply (uninterruptible power supply):

1). It is prohibited to frequently turn off and turn on the UPS backup power supply (uninterruptible power supply): Generally, it is required to wait for at least 6 seconds after turning off the UPS backup power supply (uninterruptible power supply) before turning on the UPS backup power supply (uninterruptible power supply). Otherwise, the UPS backup power supply (uninterruptible power supply) may enter a "startup failure" state, that is, the UPS backup power supply (uninterruptible power supply) enters a state of neither mains power output nor inverter output.

2). Comply with the manufacturer's product manual regulations: When using UPS backup power supply (uninterruptible power supply), it is necessary to comply with the manufacturer's product manual regulations to ensure that the live, neutral, and ground wires connected meet the requirements, and users are not allowed to change their mutual order arbitrarily. For example, the AC input wiring of the American PULSE brand UPS backup power supply (uninterruptible power supply) is exactly the opposite of the connection method of the AC input socket in China. For example, the three-phase UPS of EAST (East) needs to pay attention to phase sequence issues, otherwise there will be phase sequence error alarms, and the same applies to other brands.

3). Regularly maintain the UPS backup power supply (uninterruptible power supply): clean the dust inside the machine, measure the voltage of the battery pack, replace unqualified batteries, check the operation of the fan, and detect and adjust the system parameters of the UPS.

4). Storage location: The UPS backup power supply (uninterruptible power supply) should be placed away from direct sunlight and have sufficient ventilation space. At the same time, it is forbidden to connect inductive loads to the UPS output port.

5). Overloading is prohibited: The manufacturer recommends that the maximum starting load of UPS should be controlled within 80%. If overloaded, the inverter transistor may often break down in the inverter state. Practice has proven that for the vast majority of UPS backup power sources (uninterruptible power supplies), controlling their load within the range of 30% to 60% of the rated output power is the best operating mode.

6). Strictly follow the correct startup and shutdown sequence: avoid causing significant voltage fluctuations in the UPS backup power supply (uninterruptible power supply) when the load suddenly increases or decreases, which may prevent the UPS backup power supply (uninterruptible power supply) from working properly.