LG inverters have been rebranded as (LS) inverters. As the saying goes, "changing the soup doesn't change the medicine," so fault diagnosis and maintenance remain similar. Despite the name change, LG inverters are still widely used in China, which means failures are inevitable. Let's dive into some common faults and their solutions.
1. OC Fault: This is a typical issue found in many inverters, including LG models. An overcurrent alarm usually occurs due to incorrect parameter settings, such as acceleration or deceleration time. However, hardware-related issues can also cause this. The high-power modules may be damaged, leading to an OC fault. For example, low-power economical inverters use the TYCO PIM module, while general-purpose medium-power units often use Fujitsu or Mitsubishi IGBT modules. High-power models may use Siemens IGBT modules. Common causes of power module damage include:
- Short-circuit or phase loss in the output load.
- Excessive load causing continuous high current.
- Sudden load fluctuations that result in large surge currents, potentially damaging the power module.
2. HW Fault: This is a unique fault specific to the LG-IG5 series. Possible reasons include:
- Damaged cooling fan due to excessive bearing friction from environmental factors.
- Motherboard issues that might lead to HW failure.
3. Ground Fault (GF): This is a common issue encountered during operation. While motor grounding problems could be a cause, the most likely culprit is the Hall sensor. Environmental factors like temperature and humidity can affect the sensor’s performance, leading to drift and triggering a GF alarm.
4. No Display Fault: This usually happens when the switching power supply is damaged. Unlike standard self-excited or other-excited power supplies, LG inverters use a controllable voltage regulator called TL431 to adjust the duty cycle of the switching transistor for stable output. If there’s a short circuit, the power supply may block the output, resulting in no display on the panel.
5. FU Fault: Inverters like LG-IS5 and IH series are equipped with fast fuse detection. These fuses can break within 5 ms, protecting the high-power modules when a large current passes through. However, if the fast fuse is damaged, it can trigger a FU fault. In such cases, replacing the fuse is necessary.
Like other types of inverters, LG models may also experience faults such as LV, OV, or drive circuit damage. Continuous hands-on practice and experience are key to mastering these repairs effectively.
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