Uninterruptible power supply maintenance of common failures and skills

Uninterruptible power supply is a UPS, many friends have purchased an uninterruptible power supply after a period of time will always have problems and failures, the current UPS mainly external and built-in two categories, according to the nature of their work is divided into backup type and in-line type two. In the uninterruptible power supply maintenance process, the most difficult to solve the problem than the lack of drawings, sometimes a great deal of trouble to find the drawings, and the physical can not necessarily be right, so in the uninterruptible power supply maintenance, rely on drawings or mapping line is unrealistic.

Uninterruptible power supply role

1. Grid voltage is normal, the utility voltage is supplied to the load through the UPS voltage regulator, good performance of the UPS itself is a good AC voltage regulator, while improving the quality of power supply; at the same time, it is also charging the batteries in the machine, storage of back-up energy.

2. Grid voltage abnormalities (undervoltage, overvoltage, power loss, interference, etc.) UPS inverter will be converted to AC battery DC power to maintain the power supply to the load.

3. The UPS switches between grid power and battery power on its own to ensure uninterrupted power supply to the load. And you can choose the switching time according to the precision of the equipment.

Uninterruptible power supply features

UPS is aimed at China's power grid environment and network monitoring and network systems, medical systems and other reliability requirements of the power supply, to overcome the centralized power supply of medium-sized and large-scale computer network systems caused by the increasingly harsh power supply grid environment, the third generation of the industrial frequency of the pure on-line intelligent UPS developed with a new digital technology. dc power supply, is to maintain the DC power supply, is to maintain the formation of stable and constant current in the circuit device. Such as dry batteries, storage batteries, DC generators.

UPS and DC power supply is an important enterprise power supply protection equipment, the traditional maintenance management includes: ① daily inspection of the appearance of the regular replacement of batteries, filter capacitors, fans and other wear parts, overhaul of the battery activation, etc.; ② transformation or the use of modernization equipment, the use of high-level tools to test the performance of the battery. This management method of high investment costs, maintenance personnel workload, not easy to grasp the real-time operating status of the equipment and key data, equipment accident prevention capability is low. The implementation of online maintenance management can avoid the shortcomings of the traditional way, to obtain good benefits.

UPS in Chinese means "Uninterruptible Power Supply", is the English "Uninterruptible Power System/Uninterruptible Power Supply" abbreviation, it can protect the computer computer system. Abbreviation of "UninterruptiblePowerSystem/UninterruptiblePowerSupply", it can guarantee that the computer system will continue to work for a period of time after a power failure to enable the user to save the disk in case of emergency, so that the user will not be affected by the work of the power outage or data loss.

UPS applications

UPS is now widely used in: mining, aerospace, industry, communications, national defense, hospitals, computer business terminals, network servers, network equipment, data storage equipment, UPS uninterruptible power supply, emergency lighting systems, railroads, shipping, transportation, power plants, power stations, substations, nuclear power plants, fire safety alarm systems, wireless communication systems, Program control switches, mobile communications, solar energy storage energy conversion equipment, control equipment and its emergency protection system, personal computers and other fields.

Uninterruptible power supply repair

In the absence of drawing information on how to overhaul the UPS

In this case how to overhaul the uPs? I think the use of focused census method is not a good way. Focused census method is in accordance with the frequency of failure of components directly to the circuit board to find faults.

The use of census method of overhauling another prerequisite is to master the UPs commonly used components within the test data (preferably with the corresponding spare parts), which is the main difficulty is the good and bad integrated circuits is not easy to determine (because many digital integrated circuits in the uPS by testing in-circuit resistance or open-circuit resistance sometimes does not reflect the good and bad). However, the uPs within the integrated circuit is not a lot of types, if you can prepare a good common models, maintenance with the comparison method or replacement method will be able to better solve the problem. Commonly used integrated circuit models are: SG3524, LM339, LM393, NE555, NE556, LM317 (337), 78, 79 series of three-terminal voltage regulator (mainly 7812, with a microprocessor UPS need 7805), LM324, uA74l, uA4558 and so on. If there are conditions can then prepare some 4000 series and 74Ls series of digital integrated circuits, mainly MC140ll, MCl4069, MCl4013, MCl4066, SN74LS00, SN74LS02, SN74LS04 and SN74LS74, etc..

According to a large number of maintenance practices done by the statistics show that the UPS components in the order of frequency of failure from high to low are as follows: battery (i.e., maintenance-free lead-acid batteries in the machine, including over-discharge or charging circuit faults caused by the pseudo-damage), AC inlet circuits (including fuses, varistors, power switch, etc.), inverter tubes (including the push tube), power resistors, sample transformers, small and medium power diodes, triodes, ICs, and so on. Small and medium power diodes, transistors, integrated circuits, adjustable resistors, relays, electrolytic capacitors, small power resistors, main power transformer. Therefore, in the repair of a damaged uPS, if you can not find the circuit drawings, you can go directly to the machine to find faults in the census of suspicious components at the same time, but also pay attention to check some of the virtual welding, false welding class failure. Generally can be used to compare the method (with a good component comparison) and replacement method (with a good component replacement) to determine, as long as the UPS does not have man-made failures (such as adjustable components will be messed up, etc.) and adjustable failures, generally can be solved relatively quickly.

[Example 1]Failure phenomenon sTKuPs-500-type uPs connected to the AC power on the regulator can enter the state, but the power failure can not be inverter, only to hear the machine relay rang a few times and then no movement.

Analysis and repair first check the battery voltage in the machine, normal, there is no obvious damage to the circuit board components, four MJ4502 inverter tube is not abnormal. After the boot and then test the IC Vcc power supply is also normal, but there is no sign of inverter, which is suspected to be an IC damage. Because of the machine overhaul drawing information is difficult to find, with the road measurement judgment method is difficult to find the fault, so the replacement method is used to find the fault. The first replacement is the inverter circuit control core Icl (sG3524), with Samsung's KA3524 direct replacement, the inverter immediately after the boot is normal, proving that the failure of the machine is SG3524 damage. Icl will be replaced with a new one, the fault is eliminated.

Uninterruptible power supply maintenance skills

UPS some common faults in the overhaul

1. utility power is completely normal. Immediately after the boot into the inverter state the cause of this failure is mostly utility failure to feed into the uPS, should first check the back of the machine's power supply fuse (generally 3-5A) is not disconnected, if normal, then you should then check the machine's AC incoming circuits, which include the power switch, circuit boards, connectors, varistors, sampling transformers and so on.

[Example 2]Fault phenomenon SKs-500 type UPs can not enter the regulator state after connecting the AC power, but in the inverter state.

Analysis and overhaul of the machine found that the power supply fuse has been replaced by a bolt (many of the UPs fuse is φ6 × 30mm, while the commercially available fuse is generally φ5 × 20mm, when the fuse burned out, many users can not buy a suitable fuse, like to replace it with some other metal items), and then check the internal circuit, found that the power switch and the circuit board connection between the plug-in has been blackened. Plug-in has been blackened inside, unplugged to check the plug-in and plug-in below the double-sided circuit board copper foil have been burned. The burned part of the excavation, remove the damaged plug-in, the power switch leads directly welded to the circuit board of the corresponding soldering points, and then replace the 3A power supply fuse tube, after the boot work normally.

2. There is no response in the machine after power on. Access to the utility also does not have any response to this failure phenomenon indicates that the machine low voltage circuit (mainly control circuit) can not work, the most common reason is the machine low voltage circuit power supply is not normal, and this power supply is not normal is generally due to the machine battery is damaged (or over-discharged), low-voltage fuse damage caused by (20-40A plug-in fuse).

For the battery is good or bad, can be measured by measuring the battery ends whether 12V voltage to determine (for the use of two or two groups of batteries in series power supply models, each battery should be 12V). If the voltage at both ends of the battery is very low or no voltage, it means that there is a problem with the battery (note that sometimes it is false damage caused by over-discharge).

[Example 3]Failure phenomenon SANTAKUPS-500-type UPs connected to the power supply after the machine no response, neither voltage stabilization, nor inverter, as if no power.

Analysis and overhaul by asking the user that the UPS has been working normally, but because in the warehouse for more than a year, and then use it can not work. Had suspected that the battery put no power, but plugged into the power plug for a long time charging still can not work.

Check the machine low voltage fuse is normal, the battery only less than 5v voltage at both ends, replace the battery with a new one, the power plug into the mains, immediately after the boot is normal, in the case of charged (pay attention to safety) will be unplugged from the new battery and will be connected to the original machine battery, charging for 10 hours or so, all the machine is normal, proving that the original battery has not been damaged, but because of the long term shelves without using, the natural discharges caused by the pseudo The battery is not damaged, but is pseudo-discharged due to long-term storage.

Why does the user charge the battery himself? This is because in the UPS circuit, the control circuit itself to consume power, this part of the power is often needed by the battery to provide. When the battery voltage is insufficient or even no power, the control circuit will not be able to work correctly, even if connected to the normal utility power, the machine's control circuit can not be switched to the utility voltage regulator state, the same can not be charging the battery, unless a normal battery "start", to be UPS into the utility voltage regulator state, the battery is also After entering the charging state (at this time the battery will be disconnected does not affect the work of the UPS), and then the original battery back to charge the electricity.

It should be reminded that different models of UPS battery damage (or pseudo-damage) failure phenomenon is not exactly the same, the specific phenomenon depends entirely on the design of the circuit, in addition to the more common phenomena above, there are inverted maintenance time is too short (or even a turn to the inverter state immediately failed), connecting the mains power supply after the start-up of the relay issued by the machine, "humming" sound, the inverter is not a good idea, it is not a problem. Buzzing" sound, the work of the state of confusion, the indicator flashes, the machine relay constantly "click" sound, etc. Of course, there are also very few models in the case of battery power can automatically enter the state of the utility voltage regulator after power on (I have only encountered a trademark "$" shape model). "-like model).

For the case of damage to the low-voltage fuse in the machine, generally accompanied by a short-circuit inverter tube breakdown, at this time should first be measured by measuring the resistance to find the damaged inverter tube, so as not to replace the new fuse to expand the fault.

[Example 4]Failure phenomenon sANTAKTwinGuard-500 ultra-small high-frequency inverter UPS can not be turned on.

Analysis and repair this is the Santak company in recent years, the new development of high-frequency inverter models, the market is very popular, this UPS uses a microprocessor to control the entire machine, and the use of low-voltage power on the way (hold down the power switch for more than 3 seconds can be turned on and off).

Checking the voltage on both sides of the battery in the machine is normal, but the low-voltage fuse has blown. Further inspection of the inverter tube, found that Q09, Q10 (IRF740) between the poles have been broken, replace the new tube and replace the 30A low-voltage fuse after the boot, work normally.

3. The mains voltage regulator is normal, but there is a strong AC sound in the inverter. At the same time, the inverter output voltage is low (150V or less) This failure phenomenon is a typical manifestation of single-ended inverter, UPS inverter is composed of two (or two groups) inverter tube to push-pull mode of operation *** with the completion of the two (or two groups) inverter tube were assumed by the positive and negative half-week of the inverter task, if one of them (or a group of) open-circuit damage, this time of the UPS is often still able to invert, just inverter Output voltage is very low, and the machine transformer will issue a violent "hum" sound. The common cause of this failure is the inverter tube or push tube open-circuit, sometimes SG3524 two inverter signal output foot (⑩ and ⑩ feet) in a problem (note that the internal circuit or external circuits may cause this type of failure).

Example 5 fault phenomenon FuDA500W type uPs can enter the mains voltage regulator, but the inverter output voltage is only 100V or so, while the machine has a violent "buzzing" sound.

Analysis and overhaul of the machine's inverter tube with Motorola's high-power Darlington tube MJll0l6, power-off test two inverter tube between the feet in the road resistance, found that there is a more pronounced difference between the welded down for further measurements, found that the base of one of them and the emitter of the positive and negative resistance have been very large and identical, indicating that the tube emitter junction has been an open-circuit state, the measured resistance value! The measured resistance value is actually a composite tube within the protective resistor resistance (the resistor is connected to the tube between the base and the emitter), the bad tube for a new one, the inverter is normal after power on, the measured inverter output voltage of 250V (note that the inverter output of the common UPS is a square-wave voltage of 50Hz, when measured with the AC voltage block of the ordinary multimeter, the reading is normal, do not go to the tune of adjustable resistors within the UPS).

Tips for using an uninterruptible power supply

Uninterruptible power supply - how to extend the power supply time of the UPS?

There are two ways to extend the power supply time of the UPS system:

1. External high-capacity battery pack: according to the required power supply time outside the corresponding capacity of the battery pack, but it must be noted that this method will result in a relative increase in the charging time of the battery pack, but also increase the floor space and maintenance costs, so we need to carefully evaluate.

2. Selecting a larger capacity UPS system: This method not only reduces maintenance costs, but also allows larger capacity UPS systems to operate immediately if the load equipment is expanded.

UPS power system on and off

1. First time on

(1) close the gate in the following order: storage battery switch → automatic bypass switch → output switch is placed in the order of "ON.

(2) Press the "ON" button on the UPS startup panel, the UPS power system will start slowly, the "inverter" indicator light will be on, and the "bypass" light will be off after a delay of 1 minute, and the UPS will turn into a power supply system. After a delay of 1 minute, the "bypass" light will go out, and the UPS will turn to inverter power supply, completing the boot.

After about 10 minutes of no-load operation, the UPS will start the load in the order of load power from large to small.

2. Daily power on

Just press the UPS panel "on" button, about 20 minutes, you can turn on the computer or other instruments to use. Usually wait for the UPS start into a stable work, before opening the load equipment power switch (Note: Manual maintenance switch in the normal operation of the UPS, was "OFF" state).

3. Shutdown

First shut down the computer or other instruments, let the UPS run unloaded for 10 minutes, to be discharged after the heat inside the machine, and then press the panel "off" button.