> ## Documentation Index > Fetch the complete documentation index at: https://fop-50527c4b.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Fault Investigation Logs: Alarms and Waveforms > Use alarmg_history, dsp_wave_data, and dsp_freq_data to investigate faults, distinguish failure causes, and support warranty claims or legal disputes. When a fault occurs on a SUN2000 installation, three logs give you the information you need to understand what happened, why it happened, and who or what caused it. The alarm history tells you when and how often a fault occurred; the oscillography log shows the electrical waveform shape in the milliseconds before protection tripped; and the frequency analysis log reveals harmonic distortion that causes long-term equipment damage. The alarm history is recorded by the ARM processor, while the oscillography and frequency logs originate from the DSP processor — a distinction that matters when interpreting what each file captures. All fault logs are subject to the inverter's circular buffer. Once a block is overwritten, the data is gone permanently. Export these logs **within 30–90 days** of any event you intend to investigate, use for a warranty claim, or present in a legal dispute. ## `alarmg_history` — Alarm History `alarmg_history` is the inverter's complete event log. The ARM processor writes an entry each time an alarm starts and each time it clears. **Contents:** * Precise timestamp of each alarm's start and end * Error code identifying the alarm type **O\&M use cases:** * **Chronic grid overvoltage** — if the grid repeatedly pushes voltage above the inverter's protection threshold (error code **301**, Abnormal Grid Voltage), the inverter shuts down and loses generation. `alarmg_history` will show hundreds of timestamped events. This log is hard evidence when filing a complaint with your grid operator to demand transformer replacement or line upgrades. * **Warranty and legal claims** — because the ARM processor timestamps each event against the inverter's internal clock, the log functions as a tamper-evident record. Courts and manufacturers accept EMAP exports as evidence of operating conditions. * **Distinguishing recurring from isolated faults** — a fault that appears once may be transient; the same fault code appearing daily at the same time of day points to a systematic cause (e.g., a heavy load switching on a neighboring feeder). ## `dsp_wave_data` — Oscillography `dsp_wave_data` is generated by the DSP processor, which monitors the AC and DC buses at high speed. When a protection function trips, the DSP saves a snapshot of the voltage and current waveform from the milliseconds immediately before the trip event. **Contents:** * Waveform shape (voltage and current sinusoid) in the milliseconds preceding a protection trip **O\&M use cases:** * **Internal failure vs. external surge** — a clean sinusoidal waveform that suddenly clips or collapses from within suggests an internal inverter component failure. A sharp, high-amplitude transient spike superimposed on the waveform is characteristic of an external lightning impulse or switching surge. This distinction determines whether a warranty claim applies or whether the fault is attributed to a grid or site event. * **Warranty claims** — manufacturers require waveform evidence to process hardware warranty cases. The `dsp_wave_data` export from a failed unit is typically the first document a Huawei service engineer will request. * **Legal disputes** — if an inverter failure caused a fire or injury, the oscillography log provides objective evidence of electrical conditions at the moment of the event. ## `dsp_freq_data` — Frequency Analysis `dsp_freq_data` is also DSP-generated and captures the spectral content of the AC signal — the frequency-domain breakdown of what is present on the power line beyond the fundamental 50 Hz or 60 Hz component. **Contents:** * Spectral frequency data showing harmonic content on the AC line **O\&M use cases:** * **Harmonic detection** — elevated harmonic content (3rd, 5th, 7th harmonics) causes resistive heating in transformer windings far beyond what the fundamental current alone would produce. `dsp_freq_data` lets you identify which inverter or load on the site is the source before transformer overheating causes a failure. * **Power quality evidence** — if your transformer or switchgear is degrading faster than expected, this log provides frequency-domain evidence that can support an insurance claim or a dispute with equipment suppliers. ## Using fault logs for warranty claims and legal disputes The three fault logs together form a complete technical record of any event: 1. `alarmg_history` establishes **when** the fault occurred and **how often** it had happened before. 2. `dsp_wave_data` shows **what the electrical signal looked like** at the moment of the trip. 3. `dsp_freq_data` shows **what harmonic environment** the inverter was operating in. Because these files are binary EMAP exports from Flash memory with no editable text fields, they carry significantly more evidentiary weight than screenshots from a monitoring dashboard. When filing a warranty claim or legal case, export all three logs as a set and include the inverter serial number (Modbus register 30015) and model (register 30000) in your documentation.