Home IT infrastructure The APC BC750-RS UPS – convenient protection for the “home office”

The APC BC750-RS UPS – convenient protection for the “home office”

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The principle of an uninterruptible power supply (UPS) of the Offline type was proposed decades ago. If the supply voltage exceeds the limits set by the user, the power is automatically switched over to an inverter which draws its energy from the battery. Offline UPSs still have such undeniable advantages as compactness, ease of use and low cost. Therefore, technological progress has not led to their extinction. Not only that, but recently interest in Offline UPSs has grown again. More and more people are working remotely, from home, for which Offline UPSs are still the most convenient. Even if you use only a laptop or a tablet to work from home, the UPS will ensure the operation of a Wi-Fi router and a DECT (Digital Enhanced Cordless Telecommunication) extension cord telephone during a power outage in the house (if, of course, the respective carriers are able to provide services under such conditions). And in case of short-term failures, to avoid rebooting the Wi-Fi router and the DECT base station, which takes a lot of time.
The APC BC750-RS UPS - convenient protection for the "home office" This time we are going to talk about the APC BC750-RS UPS. We are dealing with a "classic of the genre" – Offline UPS, to which a typical desktop computer system unit can be connected, as well as some peripheral devices. Total output power can reach 750 VA, active power – 415 W. As of 2017, this output power is sufficient for professional video editing up to and including Full HD and amateur editing up to and including 4K. One of the few applications for which the power of the APC BC750-RS is not enough is powering a computer on which professional 4K video editing is performed. Also, the UPS under consideration will not be enough power for advanced gamers – they use computers, the peak power consumption of which exceeds its capabilities. But all other users will undoubtedly appreciate the relatively small size of the UPS, its easy operation, as well as its low cost. The average price of the APC BC750-RS, according to Yandex.Market, in September 2017 was 5, 220 rubles.
Specifications of APC Back-UPS BC750-RS

The APC BC750-RS UPS - convenient protection for the "home office"
The APC BC750-RS box contains only the UPS itself, as well as a quick installation guide. The software and the manual are downloaded from the Internet, which makes sense, since they are subject to change. There is also no USB cable – users usually buy their own cable of the length they need anyway. The power cable with socket is one piece with the UPS, which is convenient for home use. Also an advantage when using the device at home is that the UPS is equipped with Schuko outlets, commonly referred to as "German standard outlets". This allows computers and computer peripherals to be plugged in without special cables or wires for use in the home.
The APC BC750-RS UPS - convenient protection for the "home office"
There are four power outlets on the output. Three of them are protected by a surge suppressor filter and a battery backup. The instruction manual has a long list of devices that should not be plugged into these outlets. Common to all devices on this list is that they use electric motors powered directly from AC mains without an additional power supply. There is no direct prohibition on connecting a video projector. However, we strongly recommend that you check with your video projector supplier to determine if it can be used with this model of UPS. The fourth outlet is only protected by a filter, you can plug a wide variety of loads into it, but it will not supply power if the input voltage fails.
The UPS outputs are protected against overload. In the event that the total load on the outputs exceeds 415 W of active power (note that you have to sum the active power, and the supplied software also detects only the active component), the UPS will alarm and, if the overload is not eliminated, it will shut down after a short time. In case of a very severe overload, e.g. in case of a short-circuit at the output, the built-in fuse will blow immediately. To restore operation after such an event, simply press the button on the back of the UPS.
The APC BC750-RS also has a shutdown protection for redundant outputs against too little power consumption. If the power consumption of the load is less than 15 W, the UPS shuts down after 15 minutes. Why is this necessary? After shutting down, computers and some other types of equipment, unless you physically unplug the cable, continue to draw a small amount of power. Thus, the battery continues to drain even after the computer is shut down safely. Turning off the UPS eliminates a completely unnecessary drain on the battery. But when powering a Wi-Fi router or DECT base station, this function must be disabled.
The main task that the APC BC750-RS solves during an extended power failure is to provide power to the computer while it is placed in hibernation mode (copying the contents of RAM to the hard disk and then shutting down most of the computer components). Detecting that the input voltage has exceeded the specified limits, the UPS switches the power to the battery, sending a signal through the USB-port to the computer, where the software PowerChute is installed. This is followed by one of two possible scenarios selected by the user. Either hibernation begins after a specified time following a power failure. Or the software evaluates the time remaining until the battery is fully discharged and starts the hibernation a user-specified period of time before this event.
The APC BC750-RS UPS - convenient protection for the "home office"
PowerChute also allows the upper and lower input voltage thresholds at which to switch to the backup battery to be adjusted in 1 V increments. The optimal values of these thresholds should be such that, on the one hand, fluctuations in the computer supply voltage do not lead to loss of data, and, on the other hand, the UPS does not trip too often. The input voltage measurement function implemented in the program is supposed to help in setting the limits, but in practice it is enough to choose one of the three ready-made presets. And by default, the range corresponding to the conditions of an average city apartment is set. Through the menu PowerChute can also be set to automatically turn off the sound alarm at a certain time interval (for example, at night). In addition, PowerChute maintains power consumption statistics, logs power failures, and performs self-diagnostics of the UPS.
You can select one of the three preset input voltage ranges as well as enable/disable the output power drop protection function without PowerChute using the UPS programming mode. It is described in short installation manual, we are not going to repeat it here. We only note that the current version of PowerChute Personal Edition 3.0.2 does not provide control of the output power dropout protection, it can only be done through the programming mode.
The APC Back-UPS 750 VA manual says that the battery is not replaceable by itself. In fact, the UPS is designed to allow the battery to be replaced if necessary, but APC’s policy is understandable due to consumer safety concerns. Since the battery cannot be accessed without partially disassembling the device, there is a bright yellow jumper that can be used to disconnect the battery while transporting the device. Before the first use, it must be installed during the working hours. Also before the first use you should connect the UPS to the mains for 10 hours to charge its battery. Have a new battery installed by an authorized APC service center.
The APC BC750-RS UPS - convenient protection for the "home office"
After doing the necessary preparations we started the testing. As a load we used a system unit with Intel Core i5-4670 K processor clocked at 3400 MHz, Nvidia GTX 770 graphics card and RAM running at 1600 MHz. You can use it to work with office applications, graphics editors and perform simple video processing. During testing, the computer was used for editing photos and consumed an average of 116W.
A LATP was used to adjust the input voltage. The UPS was tested at the lower limits of the input voltages of 160; 180 and 196 V. The test showed exact correspondence of the real response voltage with the set values. But the return to normal operation occurs at voltages that are 12 V higher than the threshold.
After switching over to battery operation, the output voltage was 219 V, which is 4.8% lower than the declared nominal value of 230 V, however, it is within the manufacturer’s tolerance of ± 8% of the nominal value, and moreover, it meets the requirements of the current GOST.
The APC BC750-RS UPS - convenient protection for the "home office"
After making sure that important files would not be lost in a sudden power outage on the computer, we disconnected the USB cable, making it impossible to hibernate on command from the UPS. After that we unplugged the UPS (tricks are done by professionals, don’t try them again!) The battery life of the system unit was 14 minutes. It follows that if the load is about 116 W, you can choose the option "Keep the computer on as long as possible" and specify any time from the suggested range from 5 to 8 minutes, in any case there is a big time margin. But, if the load power is close to the limit, it is better to choose the option "Save battery power" and a small duration of the standby time.
The APC BC750-RS UPS - convenient protection for the "home office"
Finally, what we saw inside the APC BC750-RS enclosure. Most of the electronic components are located on a printed circuit board made of fiberglass. The use of this material provides high reliability. The inverter uses MOSFET transistors by International Rectifier, a world leading manufacturer of UPS components. It also uses an impressive size transformer from the famous Taiwanese manufacturer CSE Power.
The APC BC750-RS UPS - convenient protection for the "home office"
The input and outputs have ferrite filters to effectively suppress high frequency interference. On the outputs, which are automatically switched to standby power if necessary, interference is caused not only by switching, but also by the non-sinusoidal output voltage. To suppress them, a cylindrical ferrite filter made of a special alloy is used. In general, everything is well thought out in the design, as it should be for such a solid company.
The APC BC750-RS is an inexpensive, convenient UPS that is optimal for home use. However, unlike nowadays widespread ultra-compact household UPSs that look like extension cords, the APC BC750-RS is designed specifically for those who work from home in remote mode. Extensive customization options and professional-grade quality of performance allow for reliable protection of work results in the event of power failure.

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