Back-up power supply at home: UPS, generator, auto start

Recommendation points

• Household UPS Use
• Secure network configurations
• Long-term autonomous operation – we connect the generator
• Building a circuit on a multifunctional ATS

Periodic power outages can damage the entire heating system and affect the operation of household appliances. The organization of backup power supply at home is a difficult task only at first glance. In this article, we will tell you how to independently organize a backup power supply at home..

In almost any household, you can find a number of devices that it would be nice to provide with backup power. This includes a refrigerator, water pumping equipment, heating boiler, computers and telephony devices. Sudden interruption of power supply or power surges will shorten the life of the motors, possible failure of the power supplies of electronic devices.

There are two ways to reduce the impact of the city power grid on the rhythm of your life. For this, either uninterruptible power supplies (UPS) or emergency electrical generators are used..

Household UPS Use

Almost all modern desktop computers are equipped with uninterruptible power supplies to protect against data loss. Devices similar in design, but of a more powerful class, can be used to power household appliances during an emergency blackout. The specificity of their use extends up to the organization of battery storage facilities that can provide the entire house with electricity for one or two days.

And yet, in everyday life, UPSs are most widely used, protecting an individual consumer or several, combined into a dedicated line, to which a boiler room or emergency lighting can also be connected. This radically changes the power supply plan of the house, additional wiring may be required.

Inverter uninterruptible power supply system: 1 – network; 2 – battery inverter; 3 – battery bank; 4 – consumers

Before purchasing a UPS, you should draw up a list of emergency consumers and calculate their power consumed for the longest period for which a power outage is possible. In this case, both the operating mode of the equipment and past experiences of downtime without electricity must be taken into account..

For example, backup power is needed:

1. Refrigerator – 400 W, operating time – 6 h.
2. Circulation pump – 95 W, operating time – 24 h.
3. Gas boiler and boiler room automation – 85 W, operating time – 24 hours.
4. Charging laptop and phones – 200 W, operating time – 4 hours.

Thus, it is possible to determine the total consumption of devices: 2.4 + 2.28 + 2.04 + 0.8 = 7.52 kWh per day. To take into account and compensate for the temporary degradation of the UPS batteries, add 30% to this value; as a result, the required daily capacity of the UPS battery will be almost 9.8 kW / h. Allowing for emergency time will give you the power you need. Keep in mind that devices of this power class are very expensive and it is not always necessary to make an additional power reserve: since the UPS will not work under full load, the calculated capacity will be quite enough.

Secure network configurations

If it is necessary to organize backup power for one or two consumers, it is reasonable to use local UPSs. So you don’t need to rework the wiring in the house, you just need to correctly choose the place of installation of the device, and it is quite cumbersome.

In general, with a load over 3 kVA / h, it makes sense to install one backup power supply device for all consumers, organizing a dedicated line for them. Buying one powerful UPS is more profitable than several less powerful ones, in this case the costs of installing new wiring are fully justified.

Another plus of high-power UPSs is the ability to independently determine the mode and characteristics of the output current for a longer autonomous operation. The built-in charge controller in such devices significantly prolongs the life of the batteries and keeps them in full readiness even during long periods of inactivity. Most of the devices have a PC communication interface for tracking the operation log and diagnostics, and the built-in voltage regulator will eliminate voltage surges and network noise.

Long-term autonomous operation – we connect the generator

There are two ways to increase the battery life: increasing the battery fleet and using an autonomous power source. The first option is more expensive and should be used only in those conditions where the installation of an internal combustion engine is impossible, for example, in apartments or offices. A controversial question arises: why do we need a UPS with a generator??

Practice shows that the parallel use of these devices has its advantages:

1. The power supply is carried out absolutely continuously.
2. The characteristics of the current generated by portable power plants are far from ideal. The UPS stabilizer smooths out interference, has an SPD of an electronic type.
3. When operating from a generator, devices of a high power class are not required, it is sufficient that they correspond to the peak load with simultaneously switched on consumers. In the case discussed above, a 1 kVA / h UPS will suffice..

In some cases, it makes sense to use generators with autorun functionality. At the moment of switching to power from the emergency generator and in the event of emergency situations (the generator has stalled, the fuel has run out), the power is switched to the UPS. In normal mode, the generated electricity will be enough to maintain a full charge of the batteries and turn on all consumers in operation..

Hybrid uninterruptible power supply system: 1 – network; 2 – inverter; 3 – generator; 4 – battery bank; 5 – consumers

Building a circuit on a multifunctional ATS

The comfort of using a UPS is high enough that many owners think about the backup power supply for the entire power grid, and not for individual consumers. There are also several solutions for this..

If it is impossible to install the generator, the backup power function is taken over by the assembly of batteries of sufficient capacity. The type of battery is determined by the operating mode: helium batteries have the greatest cyclicity and are designed for frequent switching on, lead-acid AGM batteries are cheaper, they are optimal for use in bypass mode.

The battery park is assembled from several parallel-connected maintenance-free batteries with a capacity of 100-200 A / h. The total capacity of the park should correspond to the total energy consumption in terms of low voltage, that is, in the case considered above, the consumption of devices from the 230 V network was 9.8 kW / h or kVA / h. At a voltage of 12 V, this is equivalent to a total consumption of 816 A / h, this is how the total capacity of the fleet is determined. When assembling, it is also necessary to take into account the system’s own energy consumption and losses in low voltage wires, this is approximately 5-7% of the original power. All functions for managing the uninterruptible power supply system are taken over by an electronically controlled inverter. The cost of a device of proper quality (MeanWell) for 1 kW of peak power is $ 400-600, from 3 to 5 kW – $ 1200-1400. By the way, complex devices with the same parameters cost at least 2-3 times more..

Backup system with ATS unit: 1 – network; 2 – generator; 3 – battery bank; 4 – automatic transfer switchboard (ATS); 5 – multifunctional inverter; 6 – consumers

With a generator, the battery park can be significantly reduced to one or two hours of uninterrupted operation. But you will need to install an ATS device with a generator start function. The simplest shields of domestic production are also suitable, such as ShAPg-3-1-50 Tekhenergo (~ 20,000 rubles) or self-made ATS assemblies.