Uninterruptible power supply apc back ups. Design and repair of uninterruptible power supplies from ARS. Advantages and disadvantages of products of this brand

Problems

Average lifespan of the built-in battery in the APC Back-UPS 700 is 3-5 years(no more than 40 charge/discharge cycles during the year). After this, it loses its initial capacity and when the UPS switches to backup power mode, it simply turns off the device (if the output voltage drops below 190 V, the circuit is automatically disconnected to protect the supplied device).

Possible breakdowns

The most common failure of installed batteries is a decrease in voltage at the terminals, indicating that some of the battery sections have failed.

The complete lack of information about such common devices as uninterruptible power supplies is surprising. We are breaking through the information blockade and are starting to publish materials on their design and repair. From the article you will get a general idea of ​​the existing types of uninterruptible power supplies and a more detailed, at the circuit diagram level, about the most common Smart-UPS models.

The reliability of computers is largely determined by the quality of the electrical network. Power outages such as surges, surges, dips, and loss of power may result in keyboard lockout, data loss, or damage to the motherboard etc. To protect expensive computers from troubles associated with the power network, uninterruptible power supplies (UPS) are used. UPS allows you to get rid of the problems associated with poor quality power supply or its temporary absence, but is not a long-term alternative source of power supply, like a generator.

According to the SK PRESS expert and analytical center, in 2000 the sales volume of UPS on the Russian market amounted to 582 thousand units. If we compare these estimates with data on computer sales (1.78 million units), it turns out that in 2000, every third computer purchased was equipped with an individual UPS.

The vast majority of the Russian UPS market is occupied by products from six companies: APC, Chloride, Invensys, IMV, Liebert, Powercom. APC products have been maintaining a leading position in the Russian UPS market for many years now.

UPSs are divided into three main classes: Off-line (or stand-by), Line-interactive and On-line. These devices have different designs and characteristics.

Rice. 1. Block diagram of an Off-line class UPS

The block diagram of an Off-line class UPS is shown in Fig. 1. During normal operation, the load is supplied with filtered mains voltage. To suppress electromagnetic and radio frequency interference in input circuits, EMI/RFI Noise filters are used on metal-oxide varistors. If the input voltage becomes lower or higher than the set value or disappears altogether, the inverter is turned on, which is normally in the off state. By converting the DC voltage of the batteries into alternating voltage, the inverter powers the load from the batteries. The shape of its output voltage is rectangular pulses of positive and negative polarity with an amplitude of 300 V and a frequency of 50 Hz. Off-line class UPSs operate uneconomically in electrical networks with frequent and significant voltage deviations from the rated value, since frequent switching to battery operation reduces the battery life. The power of the Back-UPS model Off-line class UPS produced by APC is in the range of 250...1250 VA, and the Back-UPS Pro model is in the range of 2S0...1400 VA.

Rice. 2. Block diagram of Line-interactive class UPS

The block diagram of a Line-interactive class UPS is shown in Fig. 2. Just like Off-line UPSs, they retransmit alternating mains voltage to the load, while absorbing relatively small voltage surges and smoothing out interference. The input circuits use Metal Oxide Varistor EMI/RFI Noise Filter to suppress EMI and RFI. If an accident occurs in the power grid, the UPS synchronously, without loss of the oscillation phase, turns on the inverter to power the load from the batteries, while the sinusoidal shape of the output voltage is achieved by filtering the PWM oscillation. The circuit uses a special inverter to recharge the battery, which also works during power surges. The range of operation without connecting a battery is expanded due to the use of an autotransformer with a switchable winding in the input circuits of the UPS. The switch to battery power occurs when the mains voltage goes out of range. The power of Line-interactive UPS class Smart-UPS manufactured by APC is 250...5000 VA.

Rice. 3. Block diagram of an On-line class UPS

The block diagram of an On-line class UPS is shown in Fig. 3. These UPSs convert AC input voltage to DC, which is then converted back into AC with stable parameters using a PWM inverter. Since the load is always supplied by the inverter, there is no need to switch from the external network to the inverter, and the switching time is zero. Due to the inertial link direct current, which is a battery, the load is isolated from network anomalies and a very stable output voltage is generated. Even with large deviations in input voltage, the UPS continues to supply the load with pure sinusoidal voltage with a deviation of no more than +5% from the user-set nominal value. APC On-line class UPSs have the following output powers: Matrix UPS models - 3000 and 5000 VA, Symmetra Power Array models - 8000, 12000 and 16000 VA.

Back-UPS models do not use a microprocessor, but Back-UPS Pro, Smart-UPS, Smart/VS, Matrix and Symmetna models do use a microprocessor.

The most widely used devices are: Back-UPS, Back-UPS pro, Smart-UPS, Smart-UPS/VS.

Devices such as Matrix and Symmetna are used primarily for banking systems.

In this article we will look at the design and diagram of Smart-UPS 450VA...700VA models used for power supply personal computers(PC) and servers. Their technical characteristics are given in table. 1.

Table 1. Specifications Smart-UPS models from APC

*Adjustable by user using software PowerChute.

UPS Smart-UPS 450VA...700VA and Smart-UPS 1000VA...1400VA have the same electrical diagram and differ in battery capacity, number of output transistors in the inverter, power power transformer and dimensions.

Let's consider the parameters characterizing the quality of electricity, as well as terminology and designations.

Power problems can be expressed as:

In Russia, dips, dropouts and voltage surges, both up and down, account for approximately 95% of deviations from the norm, the rest is noise, impulse noise (needles), and high-frequency surges.

The units used to measure power are Volt-Amps (VA, VA) and Watts (W, W). They differ in power factor PF (Power Factor):

The power factor for computer equipment is 0.6...0.7. The number in the designation of APC UPS models means the maximum power in VA. For example, the Smart-UPS 600VA model has a power of 400 W, and the 900VA model has a power of 630 W.

The block diagram of the Smart-UPS and Smart-UPS/VS models is shown in Fig. 4. The mains voltage is supplied to the EM/RFI input filter, which serves to suppress interference from the mains. At the rated mains voltage, relays RY5, RY4, RY3 (pins 1, 3), RY2 (pins 1, 3), RY1 are turned on, and the input voltage passes to the load. Relays RY3 and RY2 are used for the BOOST/TRIM output voltage adjustment mode. For example, if the network voltage has increased and gone beyond the permissible limit, relays RY3 and RY2 connect the additional winding W1 in series with the main winding W2. An autotransformer is formed with a transformation ratio

K = W2/(W2 + W1)

less than one, and the output voltage drops. In the event of a decrease in the mains voltage, the additional winding W1 is reversed by the relay contacts RY3 and RY2. Transformation ratio

K = W2/(W2 - W1)

becomes greater than unity, and the output voltage increases. The adjustment range is ±12%, the hysteresis value is selected by the Power Chute program.

When the input voltage fails, relays RY2...RY5 are turned off, a powerful PWM inverter powered by the battery is turned on, and a sinusoidal voltage of 230 V, 50 Hz is supplied to the load.

The multi-link power supply noise suppression filter consists of varistors MV1, MV3, MV4, inductor L1, capacitors C14...C16 (Fig. 5). Transformer CT1 analyzes high-frequency components of the network voltage. Transformer CT2 is a load current sensor. Signals from these sensors, as well as the temperature sensor RTH1, are sent to the analog-to-digital converter IC10 (ADC0838) (Fig. 6).

Transformer T1 is an input voltage sensor. The command to turn on the device (AC-OK) is sent from the two-level comparator IC7 to the base Q6. Transformer T2 - output voltage sensor for Smart TRIM/BOOST mode. From pins 23 and 24 of processor IC1 2 (Fig. 6), the BOOST and TRIM signals are supplied to the bases of transistors Q43 and Q49 to switch relays RY3 and RY2, respectively.

The phase synchronization signal (PHAS-REF) from pin 5 of transformer T1 goes to the base of transistor Q41 and from its collector to pin 14 of the IC12 processor (Fig. 6).

The Smart-UPS model uses an IC12 microprocessor (S87C654) that:

The EEPROM IC13 memory chip stores factory settings, as well as calibrated settings for frequency signal levels, output voltage, transition limits, and battery charging voltage.

Digital-to-analog converter IC15 (DAC-08CN) generates a reference sinusoidal signal at pin 2, which is used as a reference for IC17 (APC2010).

The PWM signal is generated by IC14 (APC2020) together with IC17. Power field-effect transistors Q9...Q14, Q19...Q24 form a bridge inverter. During the positive half-wave of the PWM signal, Q12...Q14 and Q22...Q24 are open, and Q19...Q21 and Q9...Q11 are closed. During the negative half-wave, Q19...Q21 and Q9...Q11 are open, and Q12...Q14 and Q22...Q24 are closed. Transistors Q27...Q30, Q32, Q33, Q35, Q36 form push-pull drivers that generate control signals for powerful field-effect transistors with a large input capacitance. The load of the inverter is the transformer winding, it is connected by wires W5 (yellow) and W6 (black). A sinusoidal voltage of 230 V, 50 Hz is generated on the secondary winding of the transformer to power the connected equipment.

Operation of the inverter in “reverse” mode is used to charge the battery with pulsating current during normal operation of the UPS.

The UPS has a built-in SNMP slot, which allows you to connect additional cards to expand the capabilities of the UPS:

The UPS has several voltages necessary for normal operation of the device: 24 V, 12 V, 5 V and -8 V. To check them, you can use the table. 2. Measure the resistance from the terminals of the microcircuits to the common wire with the UPS turned off and capacitor C22 discharged. Typical faults UPS Smart-Ups 450VA...700VA and methods for their elimination are given in table. 3.

Table 3. Typical faults of Smart-Ups 450VA...700VA UPS

In the second part of the article, the On-line class UPS device will be considered,

OFF-LINE CLASS UPS DEVICE

Off-line UPSs from APC include Back-UPS models. UPSs of this class are low-cost and are designed to protect personal computers, workstations, network equipment, retail and point-of-sale terminals. The power of produced Back-UPS models is from 250 to 1250 VA. Basic technical data of the most common UPS models are presented in table. 3.

Table 3. Basic technical data of Back-UPS class UPS

The index “I” (International) in the names of UPS models means that the models are designed for an input voltage of 230 V. The devices are equipped with sealed lead-free maintenance-free batteries with a service life of 3...5 years according to the Euro Bat standard. All models are equipped with limiting filters that suppress surges and high-frequency interference in the mains voltage. The devices emit appropriate sound signals when the input voltage is lost, the batteries are low, or there is an overload. The threshold value of the mains voltage, below which the UPS switches to battery operation, is set by switches on the rear panel of the device. Models BK400I and BK600I have an interface port that connects to a computer or server to automatically shut down the system, a test switch, and a buzzer switch.

The block diagram of the Back-UPS 250I, 400I and 600I is shown in Fig. 8. The mains voltage is supplied to the input multi-stage filter through a circuit breaker. The circuit breaker is designed as a circuit breaker on the rear panel of the UPS. In the event of a significant overload, it disconnects the device from the network, while the contact column of the switch is pushed upward. To turn on the UPS after an overload, it is necessary to return the contact column of the switch to its original position. The input filter-limiter of electromagnetic and radio frequency interference uses LC links and metal oxide varistors. During normal operation, contacts 3 and 5 of relay RY1 are closed, and the UPS transmits mains voltage to the load, filtering high-frequency interference. The charging current flows continuously as long as there is voltage in the network. If the input voltage drops below the set value or disappears altogether, or if it is very noisy, contacts 3 and 4 of the relay close, and the UPS switches to operation from the inverter, which converts the DC voltage of the batteries into AC. The switching time is about 5 ms, which is quite acceptable for modern switching power supplies for computers. The load signal shape is rectangular pulses of positive and negative polarity with a frequency of 50 Hz, a duration of 5 ms, an amplitude of 300 V, an effective voltage of 225 V. At idle, the duration of the pulses is reduced and the effective output voltage drops to 208 V. Unlike Smart models -UPS, Back-UPS does not have a microprocessor; comparators and logic chips are used to control the device.

The schematic diagram of the Back-UPS 250I, 400I and 600I UPS is almost completely shown in Fig. 9...11. The multi-link power supply noise suppression filter consists of varistors MOV2, MOV5, chokes L1 and L2, capacitors C38 and C40 (Fig. 9). Transformer T1 (Fig. 10) is an input voltage sensor. Its output voltage is used to charge batteries (D4...D8, IC1, R9...R11, C3 and VR1 are used in this circuit) and analyze the mains voltage.

If it disappears, then the circuit on elements IC2...IC4 and IC7 connects a powerful inverter powered by a battery. The ACFAIL command to turn on the inverter is generated by IC3 and IC4. A circuit consisting of comparator IC4 (pins 6, 7, 1) and electronic key IC6 (pins 10, 11, 12) allows the inverter to operate with a log signal. "1" arriving at pins 1 and 13 of IC2.

A divider consisting of resistors R55, R122, R1 23 and switch SW1 (pins 2, 7 and 3, 6), located on the rear side of the UPS, determines the mains voltage, below which the UPS switches to battery power. This voltage is factory set to 196 V. In areas where the mains voltage fluctuates frequently, resulting in frequent UPS transfers to battery power, the threshold voltage should be set to a lower level. Fine adjustment of the threshold voltage is performed by resistor VR2.

During battery operation, IC7 generates inverter excitation pulses PUSHPL1 and PUSHPL2. Power field-effect transistors Q4...Q6 and Q36 are installed in one arm of the inverter, and Q1...Q3 and Q37 in the other. The transistors are loaded with their collectors onto the output transformer. A pulse voltage with an effective value of 225 V and a frequency of 50 Hz is generated on the secondary winding of the output transformer, which is used to power the equipment connected to the UPS. The duration of the pulses is regulated by variable resistor VR3, and the frequency by resistor VR4 (Fig. 10). Turning the inverter on and off is synchronized with the mains voltage by a circuit on elements IC3 (pins 3...6), IC6 (pins 3...5, 6, 8, 9) and IC5 (pins 1...3 and 11... 13). Circuit based on elements SW1 (pins 1 and 8), IC5 (pins 4...V and 8...10), IC2 (pins 8...10), IC3 (pins 1 and 2), IC10 (pins 12 and 13), D30, D31, D18, Q9, BZ1 (Fig. 11) turns on an audible signal to warn the user of power problems. During battery operation, the UPS emits a single beep every 5 seconds to indicate the need to save user files because Battery capacity is limited. When operating on battery power, the UPS monitors its capacity and emits a continuous beep for a certain time before it is discharged. If pins 4 and 5 of switch SW1 are open, then this time is 2 minutes, if closed - 5 minutes. To turn off the sound signal, you must close pins 1 and 8 of switch SW1.

All Back-UPS models, with the exception of the BK250I, have a bidirectional communication port for communication with a PC. Power Chute Plus software allows the computer to both monitor the UPS and securely automatically shut down the operating system (Novell, Netware, Windows NT, IBM OS/2, Lan Server, Scounix and UnixWare, Windows 95/98), preserving user files. In Fig. 11 this port is designated J14. Purpose of its pins: 1 - UPS SHUTDOWN. The UPS turns off if a log appears on this pin. "1" for 0.5 s.
2 - AC FAIL. When switching to battery power, the UPS generates a log on this pin. "1".
3 - CC AC FAIL. When switching to battery power, the UPS generates a log at this pin. "0". Open collector output.
4, 9 - DB-9 GROUND. Common wire for input/output signals. The output has a resistance of 20 Ohms relative to the common wire of the UPS.
5 - CC LOW BATTERY. In the event of a low battery, the UPS generates a log at this output. "0". Open collector output.
6 - OS AC FAIL When switching to battery power, the UPS generates a log on this pin. "1". Open collector output.
7, 8 - not connected.

Open collector outputs can be connected to TTL circuits. Their load capacity is up to 50 mA, 40 V. If you need to connect a relay to them, then the winding should be bypassed with a diode.

A regular “null modem” cable is not suitable for communication with this port; a corresponding RS-232 interface cable with a 9-pin connector is supplied with the software.

UPS CALIBRATION AND REPAIR

Setting the output voltage frequency

To set the frequency of the output voltage, connect an oscilloscope or frequency meter to the UPS output. Switch the UPS to battery mode. When measuring the frequency at the UPS output, adjust resistor VR4 to 50 ± 0.6 Hz.

Setting the output voltage value

Switch the UPS into battery mode without load. Connect a voltmeter to the UPS output to measure the effective voltage value. By adjusting resistor VR3, set the voltage at the UPS output to 208 ± 2 V.

Setting the threshold voltage

Set switches 2 and 3 located on the rear side of the UPS to the OFF position. Connect the UPS to a transformer type LATR with continuously adjustable output voltage. Set the voltage at the LATR output to 196 V. Turn resistor VR2 counterclockwise until it stops, then slowly turn resistor VR2 clockwise until the UPS switches to battery power.

Setting the charge voltage

Set the voltage at the UPS input to 230 V. Disconnect the red wire going to the positive terminal of the battery. Using a digital voltmeter, adjust the resistor VR1 to set the voltage on this wire to 13.76 ± 0.2 V relative to the common point of the circuit, then restore the connection to the battery.

Typical faults

Typical faults and methods for eliminating them are given in table. 4, and in table. 5 - analogues of the most frequently failing components.

Table 4. Typical Back-UPS 250I, 400I and 600I faults

Table 5. Analogues for replacing faulty components

Gennady Yablonin
"Electronic equipment repair"

APC Back UPS is a series of devices designed specifically for use in domestic conditions. Such devices are in great demand today, due to their affordable cost and sufficient (low and medium) level of performance. APC Back UPS versions are capable of operating during a power outage for a short period of time.

For what purposes are they used?

Whatever the uninterruptible power supply, its main task is always to provide the consumer with high-quality electricity, with a minimum level of noise and various types of interference for the time when there is no connection to the power grid. Back UPS is no exception, however, this group of devices was created for a certain category of consumers, which is due to the technical characteristics of the device.

Thus, the level of performance does not allow the use of this technology in harsh conditions. Recommended tasks to be solved using this group of devices are for use at home. Moreover, these uninterruptible power supplies can protect equipment from surges passing through telephone, electrical and coaxial lines.

Manufacturer information

Uninterruptible power supplies of this type are the result of the activities of the entire American Power Conversion corporation, which was registered in 1981. At the initial stage, only three engineers worked as part of the working group. Five years after its founding, the company receives its first award for its products. And until 2004, the number of awards reaches 100.

Since 2007, the corporation has become the property of Schneider Electric. But the Back UPS series of devices retained their name. Today there is a separate division, the main task of which is the development and production of equipment for protecting energy supplies.

Model overview

Back UPS comes in several variants. Each of them also has a certain number of executions:

• HS series – floor-standing single-phase devices designed for a power of 500 VA;
• APC Back UPS CS devices with power from 350 to 650 VA (desktop equipment);
• RS series – floor-standing devices with power from 500 to 1500 VA;
• APC devices Back UPS ES 400-700 VA (for desktop installation).

Devices from the latter group are widely popular, which is primarily the result of a successful balance between build quality, operational reliability and reasonable equipment cost.

Watch a video about the ES 525 model:

APC Back UPS devices of this series are presented in versions, each of which differs in power: 400, 525, 550, 700 VA. The higher the value of this parameter, the greater its performance. For example, the ES 525 version allows input voltage fluctuations in the range from 160 to 280 V, switching to battery occurs in 5 ms. The APC Back UPS ES 525 design protects the consumer from voltage fluctuations and filters noise in the network.

Depending on the load supplied to the equipment of this model, the duration of operation in offline mode will differ. Thus, the APC Back UPS ES 525 at maximum load will work for about 4 minutes, and at an average level of performance, the operating time increases almost four times. The APC Back UPS ES 525 version is equipped with 4 outlets, one of which has surge protection.

Another option of the same group is APC Back UPS ES 700. Its total output power is 700 VA, the active component is 400 W. When switching to battery power mode, a fairly high level of stability of the output voltage is observed - up to 5% fluctuations.

ES 700 series

APC Back UPS ES 700 operates in autonomous mode for almost the same length of time (3.9 minutes at full load, 15 minutes at partial load). The APC device Back UPS ES model 700 provides consumer protection from high-voltage pulses, protection of telephone lines and local networks, as well as interference filtering.

If we consider another group of devices, we can highlight the APC Back UPS CS 500 version. A single-phase device designed for power up to 500 VA.

The color scheme of the case is light. The range of fluctuations in the input network voltage is approximately the same as that of the previously considered versions: 160-282 V, while the APC Back UPS CS 500 ensures even more reliable operation of the consumer, since when switching to the autonomous power supply mode, the CS 500 model supplies no more than 3% error in voltage value. The device switches to battery mode in an average of 10 ms. It is possible to replace the battery, and for the convenience of APC users, the Back UPS CS 500 version provides a light indication.

Watch a video about the Back UPS ES 650 model:

Another popular option of the same group, which has a fairly high level of performance, is the APC Back UPS CS 650. This design is identical in a number of basic technical characteristics to the analogues discussed above (input voltage and frequency range, type of current - single-phase). APC Back UPS CS 650, as can be seen from the designation, operates at a power of 650 VA.

However, a noticeable disadvantage of this option is the short-term operation when the network is disconnected. APC device Back UPS CS in version 650 at full load operates for no more than 2.4 minutes. But we must not forget that the main area of ​​application of such equipment is home PCs, then the capabilities of the Back UPS CS 650 models are quite enough to complete work processes on the computer.

Advantages and disadvantages of products of this brand

UPS 500 Series

If you consider a number of advantages of this technique, it is understandable why it is so popular:

• Long battery life;
• The APC Back UPS series has an increased level of reliability, which is explained by the build quality;
• Consumer protection from interference, network noise and high-voltage surges;
• APC Back Series UPS protects local networks and telephone lines due to power surges;
• High speed of transition to offline mode;
• USB interface.

The only disadvantage we can highlight is the cost, since the most modest performance versions of the APC Back UPS series are offered at a price that is slightly higher than that of similar devices from other brands. But even the most affordable devices are distinguished by their quality.

For example, the APC Back UPS CS device in version 500 is offered at a price of 5,500 rubles. Accordingly, more productive equipment will cost more. But the APC device Back UPS ES model 525 is offered at a noticeably lower price - 4,400 rubles, despite the fact that its power is slightly higher than the previously reviewed version.

How do buyers evaluate products?

The APC Back UPS series equipment receives positive reviews almost universally. But there are also some comments. For example, depending on the design, the device may make noticeable noise. And the price does not always satisfy buyers; some even prefer to purchase an analogue from another company at an affordable price. Otherwise, APC devices Back UPS 500 and other models of different series of this brand have no complaints.

And in some cases, it is even possible to restore a battery that has expired. Considering that many models use maintenance-free batteries, the opportunity to restore their functions using improvised means is very attractive. In addition, the APC Back UPS ES model 525 and other versions of this series fully satisfy the requirements of customers, which is why this type of equipment is very popular.