**Document number:** CT-SOP-OM-2026-V1.0
**Document Classification:** Public (Public / For Authorized Partners)
**Scope of application:** All industrial and commercial integrated cabinets/residential microgrid energy storage systems under CoreTect assets
Chapter 2: Monthly/Quarterly Standard Inspection and Maintenance Operating Procedures (SOP)
[Training objectives of this chapter]
1. Enable operation and maintenance engineers and authorized agents to master the standardized inspection process (SOP) of the microgrid energy storage system.
2. Clarify the specific quantitative indicators and judgment standards for electrical fastening, insulation safety regulations, communication signals, and fire protection inspections.
3. Be proficient in the LOTO (Lockout and Tagout) safety isolation procedure and the RCA (Root Cause Analysis) liability determination mechanism.
4. Establish and implement a predictive life management system based on asset health score (Health Score).
2.1 Prerequisites for operation and maintenance operations (safety red line)
Safety red line warning: Any illegal opening of cabinets without PPE or without power outage and isolation is strictly prohibited! Violators will have their CoreTect Certified Engineer status revoked immediately!
2.1.1 Mandatory wearing list of personal protective equipment (PPE):
Insulated shoes (insulation level ≥ 5kV, check the soles for punctures before each wear).
Arc protection clothing (protection against strong arc splash, level ≥ 8 cal/cm²).
High-voltage insulating gloves (voltage resistance level ≥ 1000V DC, must be inflated and leak-checked before each use, and anti-cut leather gloves must be worn on the outside).
Goggles, safety helmet, portable four-in-one gas detector (hang on the chest, and can only approach the cabinet after passing the power-on self-test).
2.1.2 Preparation and verification of necessary tools:
Insulated digital multimeter and 1000V Megohmmeter, the insulation layer of the test leads is not damaged.
Insulated torque wrench (5N·m~50N·m range, must be within the calibration validity period).
Infrared thermal imager (emissivity set to 0.95).
Professional consumables: industrial lint-free cloth, electronic contact cleaner, high-voltage insulating tape (Kapton), red/blue anti-loosening marker pen.
2.2 Operation Process 1: Safety Isolation and Electricity Test (LOTO SOP)
Operating Scenario: A power outage must be performed before performing internal tightening, insulation testing, or component replacement.
1. Issue a shutdown command: Switch the system mode to "Standby" through the CoreTect Cloud platform or the local screen, confirm that the inverter (PCS) stops charging and discharging, and the current displays 0A.
2. Disconnect the AC side: Disconnect the AC main circuit breaker outside the energy storage cabinet, hang a warning sign saying "Someone is working, closing is prohibited", and use a physical safety lock (LOTO).
3. Disconnect the DC side: Open the battery compartment and disconnect the DC main circuit breaker of the high-voltage control box (HV Box).
4. Forced static discharge: it must be left for **15 minutes** and wait for the large capacitance of the PCS internal bus to be discharged.
5. High-voltage electrical test (life and death point): Wear a full set of PPE, set the multimeter to DC 1000V, and measure the DC busbar positive to negative pole, positive pole to ground, and negative pole to ground voltage.
Judgment criteria: Voltage \`< 36V DC\` is considered safe before subsequent physical contact operations can be carried out.
2.3 Operation process two: monthly/quarterly appearance and structural inspection
Inspection cycle: once a month | Responsible person: Regional junior/intermediate operation and maintenance engineer*
2.4 Operation process three: core electrical and communication maintenance (in-depth operation)
(Note: 2.4.1 is a live sweep, 2.4.2 must be executed after a complete power outage and power check)
2.4.1 Thermal imaging sweep (executed in charged state)
Under full power operation, use an infrared thermal imager to scan the PCS AC and DC copper bus connectors and battery cluster busbars.
Judgment criteria: The absolute temperature of each contact point is \`≤ 65℃\`, and the temperature difference between different phase sequences of the same busbar is \`≤ 5℃\`.
2.4.2 Insulation resistance test and torque retightening (executed in power-off state)
1. DC system insulation detection (Insulation Resistance): Use a 1000V megger to measure the insulation resistance of the DC positive pole to ground (PE) and the negative pole to ground.
Judgment criteria: Insulation resistance \`≥ 2 MΩ\` (safe); \`< 1 MΩ\` (closing is strictly prohibited and leakage breakdown points must be checked).
2. Inspection and retightening of marking misalignment: Observe with the naked eye whether the "anti-loosening paint marking" of the high-voltage copper bar is misaligned and broken. If misaligned, use an insulated torque wrench to retighten and draw a new line.
BMS voltage acquisition terminal (M5): standard torque 5 N·m.
Battery module connection copper bar (M8): standard torque 12~15 N·m.
2.4.3 In-depth inspection of battery consistency (core asset assessment)
Retrieve single cell extreme value data through CoreTect Cloud for determination:
1. Cell voltage difference (Delta-V): \`≤ 30mV\` (excellent); \`≤ 50mV\` (qualified); \`> 100mV\` (fault, need to trigger a deep equalization work order).
2. Single unit temperature difference (Temp-Diff): \`≤ 3℃\` (excellent); \`≤ 5℃\` (passed); \`> 10℃\` (serious failure, check for NTC detachment or internal short circuit).
3. Cell internal resistance (ACIR): The internal resistance deviation of each cell is \`≤ 20%\`.
2.4.4 Communication and cloud gateway system inspection (data link assurance)**
4G signal strength**: RSSI \`> -85dBm\` (lower than this value requires an external antenna).
MQTT link status**: Status = \`Connected\`.
Data upload cycle**: delay \`≤ 60 seconds\`.
2.5 Operation process four: CoreTect Cloud remote automated inspection and scoring mechanism
CoreTect’s core moat: The system automatically executes, replacing 80% of manual inspections. *
2.5.1 Daily Automated Physical Check (Daily Check) and Push **
At 2:00 a.m. every day, the cloud backend automatically pulls all online device data, generates a Daily Health Report with green/yellow/red markings, and automatically pushes it to customers and local operation and maintenance centers.
2.5.2 "Asset Health Score (Health Score)" of multi-dimensional data fusion**
Convert complex SOH, pressure difference, and historical overtemperature times into an intuitive score of 0-100 through the background AI algorithm:
🟢 90 - 100 points (Excellent): The system status is perfect.
🟡 70 - 89 points (Fair): Sub-healthy. The system pushes an early warning to the customer: "The pressure difference has expanded. It is recommended to purchase CoreTect deep equalization service to prevent accelerated degradation of life."
🔴 < 70 points (Critical): High-risk status. Trigger manual door-to-door intervention work orders.
2.5.3 SOH trend analysis (Lifecycle Management)**
Extract the system's SOH, number of complete cycles, and actual available capacity on a quarterly basis. Establish a decay trend curve and deliver the "Energy Storage Asset Health White Paper" to reflect the value of full life cycle stewardship.
2.6 Leveled Failure Response (SLA) and RCA Incident Investigation Mechanism
2.6.1 Fault rating and SLA response time**
P1 level major failure (Critical) (PCS downtime/thermal runaway alarm/full offline): The cloud responds within 30 minutes*; the local team prepares accessories and arrives at the scene within 4 hours.
P2 level general fault (Warning) (voltage difference \`> 100mV\` / slight high temperature / backup link interruption): The root cause will be identified within 4 hours, and cloud software instructions will be issued.
P3 level minor exception (Notice) (weak signal/data delay): Register and process within 24 hours, and maintain it during the next monthly inspection.
2.6.2 RCA (Root Cause Analysis) accident investigation and liability determination process for major failures
For all P1 major incidents or customer claims, a standard English RCA report (8D Reporting Method) must be issued within 48 hours, containing:
1. On-site physical evidence: Take photos to record traces of water immersion, lightning breakdown points, illegal external high-power loads, etc.
2. Cloud black box evidence: Retrieve high-frequency logs 1 minute before the crash (for example: "A sudden 300V surge broke down the equipment on the power grid").
3. Accident liability determination and blame-shifting defense: Relying on objective data links, if the problem is due to non-warranty factors such as unauthorized wiring by the customer, severe power grid impact, artificial blocking of the antenna, etc., we will resolutely issue a paid maintenance bill of "original price accessories + labor hours".
2.7 Regional warehousing and spare parts management mechanism (Spare Parts Management)
In order to ensure the SLA service timeliness, the local maintenance center (Regional Hub) must strictly implement the following warehouse disciplines:
2.7.1. Safety Stock: Standing stock of 4G DTU gateways, isolation splitters, DC circuit breakers, fuses of various types, ultra-sonic/lithium standard BMS motherboards and replacement batteries of various capacities.
2.7.2. Trade-in and write-off system (One-in, One-out): Engineers use new motherboards to go to the site for repairs. When they return, they must hand back the burned old motherboards for write-off entry to prevent spare parts from being lost or resold without permission.
2.8 Operation and maintenance closing and data closed-loop (Closed-loop)
2.8.1. Inventory tools and black box extraction: Before leaving the site, inventory all tools and tools to prevent short circuits caused by leftover metal. Forcibly download the BMS bottom-level operation logs of the past 30 days and bring them back to the laboratory for archive.
2.8.2. Restore power supply: remove the LOTO lock, close the AC and DC circuit breaker, and issue a power-on command from the cloud. There was no alarm after staying on site for 15 minutes.
2.8.3. Work order closed loop: Upload inspection photos with time watermark on the mobile terminal, customer electronic signature, and file the work order.
[Appendix: Example of entry assessment question bank for operation and maintenance engineers (Trainee Assessment)]
Q1 (theoretical safety): Why does the energy storage cabinet have to be left alone for 15 minutes and tested with a megger after the power is turned off?
Answer: It is for the discharge of the PCS internal bus capacitance; the megohmmeter detects the insulation resistance to be ≥ 2 MΩ to prevent high humidity and condensation from causing electric shock or deflagration at the moment of closing.
Q2 (Business Risk Control): During the inspection, it was found that the "CoreTect official anti-tamper sticker" on the battery cabinet was torn, or there were signs of unauthorized connection by the customer. What is the first action?
A: It is absolutely forbidden to touch the device! Immediately take photos at a blind spot to collect evidence and have the customer representative sign for confirmation. The equipment automatically loses its free warranty and becomes a high-priced paid rescue order. *