Part 6: Hardware equipment level inspection and operation and maintenance SOP of the battery system on the energy storage side of the photovoltaic power station
This article corresponds to the panoramic topology diagram of the energy storage power station [Module 6: Battery System Hardware], covering personal protection (PPE) and gas pre-inspection when entering the high-voltage area of the battery compartment, high-voltage box (BDU) main contactor and pre-charge circuit, manual maintenance switch (MSD), high-voltage connection copper bar fastening and anti-corrosion temperature measurement, battery Pack module, cold plate quick-change connector and single cell physical structure inspection.
1. Safety protection pre-inspection and personal protective equipment (PPE) specifications before entering the cabin
High-voltage direct current of up to 1000V ~ 1500V is concentrated inside the battery compartment, which carries the risk of high-voltage electric shock and arc burns. The "three inspections, one wearing and one monitoring" pre-inspection procedure must be strictly implemented:
(1) Forced ventilation and gas safety testing when entering the cabin
Explosion-proof forced ventilation: Before opening the door, press the strong exhaust button outside the cabin to forcibly start the explosion-proof exhaust fan in the cabin for ventilation for no less than 5 minutes.
Gas detection standards: Use a calibrated portable four-in-one gas detector to probe into the cabin at three different heights for sampling tests:
Carbon monoxide (CO): must be 0 ppm (> 24 ppm indicates that the internal separator of the battery cell has smoldering and depolymerized);
Hydrogen (H2): must be 0 ppm (> 100 ppm indicates serious overcharging of the battery cell with hydrogen evolution);
Lower explosion limit of flammable gas (LEL): must be < 1% LEL; oxygen concentration (O2): must be ≥ 19.5% (anti-suffocation).
(2) Human body static electricity elimination and PPE protection specifications
Static elimination: Before entering the cabin, touch the "human body static discharge ball" next to the cabin door with your palm for no less than 3 seconds.
PPE wearing standards: Operation and maintenance personnel must wear anti-static cotton overalls, non-slip insulating shoes (withstand voltage ≥ 10kV), 1000V/1500V-level insulating gloves and arc-proof masks.
On-site air entrainment test of insulating gloves: before wearing, roll the glove sleeve toward the fingertips and observe that the glove expands without bubbles, air leakage, or pinhole damage.
Double supervision mechanism: It is strictly prohibited for one person to enter the battery compartment alone to work! It must be operated by one person and supervised by one person. The guardian holds a portable high-voltage cut-off switch and an emergency rescue insulating hook.
2. High voltage box (BDU/BCU) equipment level maintenance and testing
The high-voltage box (BDU - Battery Disconnect Unit) is the high-voltage master control center of each battery cluster, integrating the main contactor, precharge circuit, high-voltage main fuse and MSD.
(1) DC main contactor adhesion test and contact resistance temperature measurement
Contact sticking (contact welding) diagnosis SOP: After the BMS issues the opening command, use a multimeter to measure the impedance between the incoming and outgoing terminals of the main positive contactor (Main+) and the main negative contactor (Main-).
Standard: Impedance in disconnected state must be > 100 MΩ. If the impedance is close to 0 Ω, it is determined as a contact adhesion failure. The contactor cannot cut off the high voltage due to arc welding. The power must be stopped immediately and the contactor must be replaced.
Contact voltage drop and contact resistance test: With the contactor in the closed state, use a microohmmeter to apply a 10A DC current to measure the main contact resistance, which must be ≤ 0.5 mΩ. If the resistance is too high, the contactor will heat up violently during charging and discharging.
(2) Precharge circuit parameter verification and response time
Precharge resistor maintenance: Check that the ceramic shell of high-power precharge resistor (such as 50 Ω / 100 W) has no cracks, desoldering or blackening. The measured resistor impedance must be within ± 5% of the nominal value.
Precharge control logic verification: After the precharge contactor is closed, the precharge current charges the PCS bus capacitor. The precharge time must be controlled between 100 ~ 300 ms; when the bus voltage reaches ≥ 95% of the cluster voltage, the main contactor can be closed, and then the precharge contactor is disconnected. If the precharge time is > 1000ms, the BMS must report "precharge timeout" and force a trip.
(3) Inspection and maintenance of high-voltage main fuse and MSD manual maintenance switch
High-voltage main fuse (Master Fuse): Check that the 1500V DC / 315A~400A master fuse collision indicator does not pop out. The impedance measured at both ends of the fuse must be < 0.1 mΩ.
Manual maintenance switch (MSD - Manual Service Disconnect):
Function: Pull out the MSD during maintenance to physically cut the 1000V ~ 1500V high-voltage battery cluster into two safe voltage segments lower than 750V.
Check: Check that the high-voltage interlock (HVIL) control pins inside the MSD are not bent or broken. Test the MSD plug-in and pull-out torque smoothly, and the contact resistance must be ≤ 1.0 mΩ.
3. Battery cluster (Cluster) and high-voltage busbar connection maintenance SOP
The battery cluster is composed of multiple battery packs connected in series on a stand. The high-voltage busbar in the cluster carries the total current of the entire cluster.
(1) Standard comparison table for tightening torque of high-voltage copper row bolts
Operation and maintenance personnel must use an insulated torque wrench that has been measured and calibrated to conduct random inspections of all high-voltage copper bars and pole bolts in the battery cluster (the inspection rate is not less than 20%), and redraw the anti-loosening marking lines:
(2) Infrared thermal imaging temperature measurement and anti-oxidation treatment SOP
Temperature measurement standard: When the battery cluster is charged and discharged at a constant current of 0.5C for 30 minutes, use an infrared thermal imager to scan all copper bars and pole bolts.
The operating temperature of bolts and copper bar nodes must be < 60.0 ℃; the temperature difference of all connection nodes in the same battery cluster must be ΔT ≤ 5.0 ℃. Exception handling SOP: If the temperature of a certain pole connection point is > 70.0 ℃ or the temperature difference with the adjacent node is ≥ 15.0 ℃, it is determined that the contact resistance is too large and the heat is generated:
Step 1: Disconnect the main circuit breaker of the battery cluster and pull out the MSD to perform electrical testing and grounding.
Step 2: Remove the connecting bolts and copper bars at the heating pole.
Step 3: Use 1000-grit fine sandpaper to lightly polish the contact surface between the pole and the copper bar to remove the patina and black oxide layer.
Step 4: Use isopropyl alcohol wipes to wipe away the debris, and evenly apply a thin layer of anti-oxidation conductive paste (thickness 0.1 ~ 0.2 mm).
Step 5: Reinstall the copper bar, use a torque wrench to tighten the bolts according to the standard torque (M8: 18~20 N·m), and re-tie the anti-loosening wire.
4. Battery Pack module and single cell physical structure maintenance
(1) 280Ah / 314Ah hard-shell LFP battery core deformation and explosion-proof valve detection
Cell swelling and thickness control: Use a vernier caliper to measure the thickness of the cell center point. The initial thickness of the new 280Ah/314Ah LFP cells is approximately 71.5 ± 0.5 mm.
Control line: When cyclic aging causes the expansion thickness of the battery core to increase > 5% (i.e. thickness increase > 3.5 mm) or the pack module end plate deformation > 3.0 mm, it means that the internal stress of the battery core is too high, and it is necessary to apply for decommissioning and replacement.
Explosion-proof valve (pressure relief valve) status inspection: Check the aluminum explosion-proof film on the top of the battery core. The explosion-proof membrane must be flat without bulges or cracks.
Judgment: If white or yellow-brown crystal particles (electrolyte evaporation residue) appear around the explosion-proof membrane, it means that the battery core has experienced micro-jet or leakage, and the battery core is judged to be a seriously dangerous product and must be immediately isolated and scrapped.
(2) Inspection of the quick-change joint of the liquid-cooled cold plate inside the Pack
Check the self-sealing liquid cooling quick coupler (Quick Coupler) at the water inlet and outlet of each Pack.
Maintenance: The quick-change joint must be free of any traces of blue or red antifreeze crystals. Use a water mark test paper close to the joint gap to confirm that there is no trace leakage; check that the airgel insulation pad between the cells inside the Pack does not absorb water, swell and deteriorate.
Photovoltaic power station energy storage side battery system hardware equipment level on-site inspection sign-in form
Power station name: _______________________________ Inspection date: ____ month ____ day, 2026
Inspection area: high-pressure area inside the battery compartment (cluster 01~08) Inspection person in charge: ____________________
1. Field equipment inspection and test data records:
2. Inspection defect registration and defect elimination dispatch:
3. Inspection sign-in and review signature:
Inspection engineer (signature): _______________ Supervision engineer (signature): _______________
Review (signature) of the shift leader: _______________ Sign-in and filing time: ____ hour on ____ month ____ day 2026