Starting a compressor in any modern refrigeration system is a process accompanied by a short-term but powerful surge in energy consumption, which is technically called inrush current. For equipment owners LG this parameter is critical when selecting protective automatic equipment, such as voltage stabilizers or uninterruptible power supplies. Understanding the physics of this process allows you to prevent false triggering of circuit breakers and extend the service life of the electric motor.
Unlike the normal operating mode, when the refrigerator consumes 100–150 watts declared by the manufacturer, at the moment of start there is a sharp surge of current, which can exceed the rated values by 3–5, and sometimes 7 times. It is this factor that often causes lights to flicker in an apartment or traffic jams to break if the wiring is designed for maximum loads. Let's look in detail at what numbers are typical for different models and how to properly organize the power supply.
Physics of the process and nominal values
The operation of the refrigeration unit is based on asynchronous electric motor, which drives the piston group of the compressor. At rest, the motor windings are cold and their electrical resistance is minimal. When voltage is applied at the start, a so-called rotor short circuit current occurs, which creates the necessary torque to break the piston from its place.
For household models LG with linear or standard inverter compressors, the rated operating current is usually from 0.5 to 0.8 Ampere. However starting current in the very first second of operation it can reach values from 3 to 5 Amperes, and in rare cases, with low voltage in the network or a difficult start, the jump can be even higher. The duration of this pulse is extremely short - it is a fraction of a second, usually from 0.1 to 0.5 seconds, after which the current drops to operating values.
It is important to consider that modern inverter models LG Linear Inverter work on a different principle. They do not have a hard starting torque in the classical sense, since the engine speed changes smoothly. However, even in such systems, upon initial start-up or after a long stop, increased consumption is observed, although less pronounced than with old atmospheric compressors.
⚠️ Attention: If, when the refrigerator is turned on, the circuit breaker in the entire apartment immediately turns off, this indicates that the threshold value of the circuit breaker current is too low for the starting surge of your model, or there are hidden defects in the wiring.
The energy spent on this short-term burst is small in terms of kilowatt-hours, so it is practically not reflected in electricity bills. However, the mechanical and electrical load on the nodes at this moment is maximum. That is why frequent restarts (for example, with unstable voltage) are considered the main enemy of the compressor, quickly wearing out the oil and mechanical friction pairs.
Factors influencing the strength of the starting current
The value of the starting current is not constant and depends on many variable factors. The first and most important condition is residual pressure the refrigerant system. If the refrigerator has recently turned off and the pressure in the circuits has not yet equalized, the compressor requires significantly more effort to start moving the piston, which causes a higher current jump.
The temperature of the motor windings also plays a role. During a cold start, the resistance of the copper winding is lower, which theoretically could increase the current, but the viscosity of the compressor oil at low temperatures, on the contrary, makes starting difficult. In hot weather, when the refrigerator is already working at its limit, the starting characteristics may differ from the passport data.
The quality of the power supply is another critical factor. When the network voltage is low (for example, 190–200 Volts instead of 230), the starting torque of the engine drops, the acceleration time increases, and the current can remain high for a longer time. This creates a dangerous situation when the thermal relay does not have time to operate, and the windings are already beginning to overheat.
- 🔌 Wiring condition: Old aluminum wiring with oxidized contacts in the socket creates additional resistance, which can lead to a voltage drop at the time of start-up and an increase in the duration of the starting pulse.
- 🧊 Filling of the chambers: An empty refrigerator starts up easier than a fully loaded refrigerator, since the heat capacity of the internal environment affects the frequency and duration of operating cycles, although this affects the starting current itself indirectly through freon pressure.
- ⚙️ Compressor wear: In older models LG with the production of mechanical components friction increases, which requires more effort to start and, accordingly, a higher current.
Power calculation and selection protective equipment
When choosing a voltage stabilizer or generator for autonomous power supply, you must focus not on the rated power indicated in the passport (usually 150–300 W), but on the peak load. To correctly select equipment, you should multiply the rated power by the safety factor, which for refrigerators LG is usually taken to be 3–5.
For example, if the nameplate of your refrigerator indicates a power of 200 W, then the starting power can reach 600–1000 W. If you purchase a 500 VA stabilizer, it can be protected every time the compressor starts. Therefore, for one refrigerator LG it is recommended to take a stabilizer with a power of at least 1–1.5 kVA.
Particular attention should be paid to the type of stabilizer. Relay models have their own response time and may not have time to compensate for the jump, and their own relays also create clicks when switching. Electronic (thyristor) and inverter stabilizers cope with a smooth voltage supply better, providing a softer start for the engine.
⚠️ Attention: When calculating the power of a generator for a summer cottage or camping, remember that cheap models often do not have an overload reserve. Starting the refrigerator can cause a drop in frequency and voltage at the generator output, which will lead to failure of the control electronics LG.
It is also important to take into account the total load if several devices are connected to one stabilizer. It is better to separate the refrigerator into a separate group or use individual protection devices. This will avoid situations where a powerful starting current damages the sensitive electronics of a TV or computer connected to the same line.
☑️ Checking the electrical network for the refrigerator
Comparison table: Conventional vs Inverter compressor
Compressor production technologies have stepped far forward, and the difference between classic models and modern inverter systems LG Linear Inverter is colossal. Understanding these differences helps to assess the real load on the network and choose the right operating strategy.
Classical compressors operate on the “on-off” principle. They always start with maximum effort, overcoming the pressure difference. Inverter models, after the initial start-up, often simply reduce speed, maintaining the temperature, which eliminates repeated powerful surges of current for a long time.
| Parameter | Atmospheric compressor (Old LG) | Inverter compressor (LG Linear) |
|---|---|---|
| Starting principle | Sharp start with maximum current | Smooth acceleration (Soft Start) |
| Starting current | High (up to 5-7 times the nominal) | Minimum (almost equal to operating current) |
| On frequency | Multiple cycles start/stop | Works constantly at low speeds |
| Influence on the network | Causes power surges, flickering lights | Almost invisible to the network |
| Energy efficiency | Class A or B | Class A++ or A+++ |
The table shows that owners of new models LG with inverter motors do not have to worry about starting currents in the same to the same degree as owners of equipment from previous years. However, this does not mean that you can ignore the quality of the voltage in the network, since the inverter electronics are even more sensitive to interference.
Why are inverter refrigerators quieter?
The secret of silence lies in the absence of sudden starts. The compressor does not accelerate sharply to maximum speed, but operates in a gentle mode, which reduces vibration and noise of mechanical parts.
Wiring problems and false alarms of automatic machines
One of the most common problems that users encounter is the breakout of the circuit breaker in the panel exactly when the refrigerator is turned on. This occurs when the response characteristics of the machine do not match the type of load. Refrigerators, like devices with electric motors, are characterized by high short-term overload.
Circuit breakers are divided into classes according to the time-current characteristic. The most common class "B" triggers when exceeding the nominal value by 3-5 times instantly. If you have a 10-amp machine of class “B”, then a starting current of 40–50 amperes (which is theoretically possible during a short circuit, but not when starting the motor) will knock it out, although the actual starting current of the refrigerator may be right in this zone of short-term excess.
To solve this problem, electricians often recommend replacing machines with a class. "C", which holds the overload 5–10 times longer. This allows the starting pulse to pass through the machine without breaking the circuit, since the thermal relay inside the machine simply does not have time to heat up within 0.2 seconds of the compressor starting.
- 🔍 Diagnostics: If the machine knocks out regularly, check its rating. For a kitchen where there is a refrigerator, microwave and kettle, they usually install 16A class "C" machines.
- ⚡ Hidden defects: Sometimes the problem lies not in the machine, but in poor contact in the machine itself or twisted wires, where resistance causes heating and simulates an overload.
- 🏠 Old wiring: In old houses with aluminum wires, the cross-section may be insufficient for modern powerful devices, which causes a voltage drop and an increase in current.
⚠️ Attention: It is strictly forbidden to increase the rating of the circuit breaker (for example, change 10A to 25A) without replacing electrical wiring! This can lead to overheating and melting of the insulation of old wires, which will cause a fire.
Soft start devices: necessity or excess?
There is an opinion that to protect the refrigerator LG it is necessary to install a device soft start (SCP). These devices limit the current at the moment of start, gradually increasing the voltage on the motor windings. For older models with powerful compressors, this could be important to reduce the load on the network.
However, for modern technology LG installation of external soft starters is most often not required and is not even recommended by manufacturers. Firstly, modern compressors are already equipped with built-in protection and startup optimization systems. Secondly, interfering with the power circuit of a complex electronic device can disrupt the operation of its own diagnostic system.
Moreover, the use of cheap Chinese soft starters can lead to the fact that the engine will not be able to develop sufficient torque to start, especially if high freon pressure remains in the system. This will lead to humming of the compressor and its eventual combustion due to operation in the “locked rotor” mode.
If your goal is to protect equipment from network surges, it is better to invest in a good voltage control relay (VCR) that will turn off the device in case of emergency indicators in the network and will turn it on only after the parameters are normalized. This will prevent the compressor from operating in abnormal modes.
Diagnostics of faults by starting current
Measuring the starting current can be an excellent diagnostic tool for the master. If you have a current clamp, you can assess the condition of the compressor without disassembling it. A normal starting impulse should be sharp and short. If the current remains high for 1-2 seconds or more, this is an alarming signal.
Prolonged high current at start-up may indicate a mechanical wedge of the piston group, jammed bearings or loss of compression. This may also be a sign of an interturn short circuit in the motor windings, when the resistance drops and the current rises, leading to rapid overheating and tripping of the thermal relay.
In some cases, high current is observed due to a faulty starting relay. If the relay contacts are stuck or burnt, they may not ensure normal switching of the windings, and the engine tries to start on one working winding, which is difficult and energy-consuming for it.
- 📉 Low current: If, when turned on, the current almost does not increase (remains at 0.1–0.2 A) and the compressor hums, but does not start, the starting winding is most likely broken or faulty starting relay.
- 📈 High current without starting: The current immediately jumps to the maximum and after a few seconds the protection is triggered. This is a sign of a compressor wedge or an insulation breakdown.
- 🔄 Cyclic surges: The compressor tries to start, the current rises, then drops, and the process repeats every 2-3 minutes. This is a classic symptom of a faulty starting device or low voltage in the network.
Timely contacting a specialist if abnormal energy consumption is detected at the time of start-up will avoid costly replacement of the compressor. Repairs at an early stage, for example, replacing a starting relay or capacitor, are much cheaper.
Is it possible to measure the starting current with a conventional multimeter?
No, most household multimeters do not have time to record a short-term jump lasting a fraction of a second. To do this, you need a special current clamp with the InRush function (inrush current) or an oscilloscope.
Frequently asked questions (FAQ)
Why does the LG refrigerator hum and click, but does not start?
This is a classic sign that the inrush current is high and the compressor cannot overcome resistance. Most often the problem is a faulty start relay (it clicks when trying to start the engine) or a wedge in the compressor itself. Also, the reason may be a critically low voltage in the network.
Do you need to buy a stabilizer for a new LG refrigerator?
If you have a stable voltage in the network (220-230V) without sudden jumps, then a stabilizer is not necessary. However, in conditions of frequent voltage fluctuations, typical of rural areas or old areas, the stabilizer will significantly extend the life of the electronic control board and the compressor.
How many amperes does the LG refrigerator consume in normal mode?
In normal operation, after startup, consumption ranges from 0.5 to 0.9 Amperes, depending on the model and volume of the chambers. The main energy consumption is spent on maintaining the temperature, and not on its initial decrease.
Can inrush current damage LED lamps in a chandelier?
Theoretically, a sharp surge of current can shorten the life of any equipment, including LED lamps, especially cheap ones. However, modern lamp drivers are protected. If the light dims greatly, this indicates poor contact in the wiring, which is more dangerous for the wiring itself than for the lamps.
Does the filling of the refrigerator affect the starting current?
The filling of the chambers does not directly affect the value of the starting current at the moment of start. The current depends on the electrical and mechanical parameters of the motor. However, full load affects the duration of operation of the compressor and the frequency of its switching on, which indirectly affects the overall resource.