(See above)
Sudden power outages or sharp surges in network voltage can be fatal for modern household equipment. Refrigeratorbeing one of the most important appliances in the home, it is especially vulnerable to power outages power supply. The compressor, which is the heart of the unit, with frequent switching on and off without protection, quickly fails, and the products lose their properties.
That is why the question of choice uninterruptible power supply (UPS) becomes critically important for many equipment owners. A properly selected device will not only ensure that the refrigerator operates for several hours during blackouts, but will also filter out interference, extending the life of the electronics. However, many users make the mistake of buying the first UPS they come across, without taking into account the starting currents.
In this article we will look in detail at how to calculate the required power, why ordinary computer uninterruptible power supplies are not suitable for motors and what parameters you need to pay attention to first. Understanding the physics of how a compressor works will help you avoid costly breakdowns.
Why choosing the right type of UPS for a refrigerator is important
Not all uninterruptible power supplies are the same, and this is a fundamental fact that beginners ignore. Standard office ones designed for computers often have an approximate sine wave at the output. For a refrigeration compressor, which is an inductive load, this form of current can cause overheating and humming. UPS, intended for computers, often have an approximate sine wave at the output. For a refrigeration compressor that is an inductive load, this current waveform can cause overheating and humming.
In addition, the switching time to batteries for cheap models can be 10-20 milliseconds. Although this is invisible to the computer, the sensitive electronics of the refrigerator control or the motor itself may perceive this as an open circuit and go into protection or try to start again, which leads to wear.
⚠️ Attention: Using a UPS with a modified sine wave (stepped) can lead to overheating of the motor windings and a reduction in the compressor life by 30-40%.
The optimal solution for refrigerators are models like On-Line or high-quality Line-Interactive with a pure sine wave at the output. They provide a stable voltage of 220V and instant switching, which is critical for inverter models of refrigerators, which are very sensitive to the quality of the incoming current.
Calculation of starting currents and power consumption
The most common mistake when choosing a UPS is focusing only on the rated power indicated in the refrigerator’s data sheet. In reality, at the moment of startup, the compressor consumes a current that is 3-7 times higher than the operating current. If the UPS power does not have a reserve, the overload protection will work and the device will turn off.
To understand which Volt-Ampere (VA) your device needs, you need to look at the sticker on the back of the refrigerator. The rated power is indicated there, for example, 200 W. However, the starting power can reach 1000-1200 W. It is for this peak that the uninterruptible power supply should be designed.
For an accurate calculation, use the following logic: multiply the rated power by a factor of 5. If the refrigerator is old or has one powerful compressor, the coefficient may be less (3-4), but for inverter systems it is better to take the maximum margin, since their control electronics complex.
Why is the starting current so high?
At the moment of starting, the motor rotor is stationary, and enormous force is required to spin it. The electrical resistance of the windings at this moment is minimal, which leads to a short-term but powerful jump in current consumption.
It is also worth considering that over time the compressor wears out, and starting currents can increase. Therefore, buying a UPS “back to back” in terms of power means saving on the longevity of the equipment. It is better to take a model with a margin of 20-30% above the calculated peak value.
Table of correspondence between UPS power and refrigerator type
To simplify the choice, you can use approximate data. Below is a table that will help you navigate the required power class of an uninterruptible power supply depending on the size and type of your refrigeration equipment.
| Refrigerator type | Rated power (W) | Recommended UPS power (VA) | Required reserve |
|---|---|---|---|
| Small (up to 200 l) | 100-150 W | 600-800 VA | 3-4 times |
| Medium (200-350 l) | 150-250 W | 1000-1500 VA | 4-5 times |
| Large (Side-by-Side) | 300-400 W | 2000-2500 VA | 5-6 times |
| Two-compressor | 250-350 W | 1500-2000 VA | Amount of starts |
| Inverter | 100-200 W | 1000-1500 VA | High (for electronics) |
Pay attention to the column with Volt-Amps. UPS power is often specified in VA rather than Watts. The conversion factor (power factor) is usually 0.6-0.7. This means that a 1000 VA UPS will actually produce about 600-700 W of active load, but it must withstand a short-term overload of 2-3 times.
If your refrigerator belongs to the category Side-by-Side or has a system No Frost with powerful fans and defrost heaters, calculations are needed keep track of the maximum sum of all consumers that can turn on at the same time.
Battery life: myths and reality
Many users mistakenly believe that by connecting the refrigerator to a UPS, they will ensure its operation for 8-10 hours. This is a misconception. Standard uninterruptible power supplies have built-in batteries of small capacity, which are designed for the correct shutdown of the PC, and not for long-term operation of the motor.
The actual operating time from a standard UPS with a power of 1000-1500 VA ranges from 15 to 40 minutes. This time is enough to “wait out” short-term surges or shutdowns, but not enough for a full freezing cycle. For long-term autonomy, external batteries are required.
⚠️ Attention: Operating time directly depends on the state of charge of the batteries and the ambient temperature. In the cold (if the UPS is in an unheated garage next to the freezer), the capacity of lead-acid batteries drops to 50%.
If blackouts in your region last for hours, it makes sense to consider a UPS with the ability to connect external batteries or use inverter systems with a separate battery bank. However, the cost of such a solution may exceed the price of a new refrigerator.
It is also worth remembering that the refrigerator operates cyclically. It turns on, cools the chamber and turns off. Therefore, the actual support time may be longer than the calculated one if the compressor operates intermittently.
Instructions: how to connect and configure the UPS
The process of installing an uninterruptible power supply does not require special knowledge, but following the sequence of actions guarantees safety. First, make sure that the installation location is dry and ventilated, as batteries may emit gases when operating.
Plug the UPS into an outlet, but do not plug the refrigerator into it yet. Allow the device to charge for 6-8 hours if it is new. This is necessary to activate the chemistry in the batteries and calibrate the electronics.
☑️ Check before starting
After charging, turn on the uninterruptible power supply itself. Make sure it has switched to mains mode (usually the green light is on). Only after this, connect the refrigerator cord to the outlet on the UPS case.
It is important not to overload other outlets on the UPS case with third-party appliances, such as kettles or microwaves. These devices create enormous interference and can instantly destroy the UPS. The purpose of the device is only a refrigerator. electronics The UPS is faulty. The purpose of the device is only a refrigerator.
To monitor the status, you can use software if the UPS is connected to a computer via USB, or simply monitor the indication. Some models allow you to adjust the sensitivity to input voltage, which is useful in areas with an extremely unstable network.
Frequent errors during operation and maintenance
Alone One of the main problems is ignoring battery life. The average battery life in a UPS is 3-5 years. After this period, it loses capacity and cannot provide the declared protection, turning into ballast.
Also, users often forget about the temperature regime. Placing a UPS near the hot back wall of a running refrigerator is a bad idea. High temperatures accelerate the degradation of the electrolyte and can lead to swelling of the battery case.
Another mistake is the use of extension cords. The UPS must be connected directly to a wall outlet. Long, cheap extension cords create additional resistance and can cause a fire at high starting currents.
⚠️ Attention: If you plan (more than 2 weeks) not to use the UPS, disconnect it from the mains and from the refrigerator. Constantly recharging a fully charged battery reduces its life.
Carry out a test shutdown regularly, at least once every six months. Unplug the UPS and see how long it can hold the load. If the operating time has dropped to 1-2 minutes, it’s time to change the batteries.
Is it possible to use a car battery?
Theoretically, yes, if the UPS supports connecting external batteries and has a charger with the correct charge current (usually 10% of the capacity). However, car starter batteries (SLI) are not designed to be deeply discharged and will quickly die in UPS mode. You need AGM or GEL batteries.
Final recommendations for selection
When choosing protection for a refrigerator, do not chase the lowest price. Cheap Chinese models often have real characteristics that are 30-40% lower than declared. It is better to choose a trusted brand that specializes in industrial or medical equipment, where reliability comes first.
Pay attention to the availability of a warranty and the availability of service centers. Batteries is a consumable item, and the ability to easily replace them is an important criterion. Some models are soldered or have unique connectors, which makes their replacement difficult and expensive.
As a result, the ideal UPS for a refrigerator is a device with a pure sine wave, a power 5-6 times higher than the rating of the refrigerator, with the ability to connect external batteries and an intelligent charge management system.
FAQ: Frequently Asked Questions
Can a regular computer UPS be used for a refrigerator?
It is highly not recommended. Computer UPSs often produce a modified sine wave, which is harmful to the engine. In addition, their power rarely exceeds 400-600 VA, which is not enough for the starting current of the compressor.
Will the UPS work if the mains voltage simply drops to 180V?
Yes, good models Line-Interactive i On-Line have a wide input voltage range. When it drops below the threshold (usually 190V or 170V depending on settings), the device will switch to the batteries, protecting the refrigerator from operating on low voltage.
Does the UPS for the refrigerator need to be grounded?
Yes, grounding is necessary. It ensures proper operation of interference filters and safety. Without grounding, static electricity can accumulate on the body of the refrigerator and the UPS, and the surge protection will not work correctly.
How often do you need to change the batteries in the UPS?
On average, every 3-4 years of active use. If power outages are frequent, the period may be reduced to 2 years. The signal is a reduction in battery life and frequent beeps from the device.