In recent years, the global energy storage market has shown explosive growth. According to relevant data, the new installed capacity of global energy storage in 2024 is about 175.4 GWh, and it is expected that the new capacity will reach 247 GWh in 2025, an increase of 35% year-on-year. However, with the expansion of energy storage scale, safety accidents have also increased year by year. Statistics show that from January to May 2025, there were 18 new energy storage-related safety accidents worldwide, of which system-level defects accounted for as high as 72%. As "invisible killers" of energy storage systems, insulation failures and leakage have become the core risks that threaten system safety. This article will focus on insulation faults in electrochemical energy storage systems and explore the application of leakage monitoring technology. CHIPSENSE leakage current sensors will play an important role in it.

Analysis of energy storage system structure and leakage risk source

1. Energy storage system architecture

• Electrochemical energy storage systems (ESS) are mainly composed of the following components:
  Battery pack: energy storage core, providing power storage and release.
  PCS (Energy Conversion System): To achieve bidirectional conversion between DC and AC.
  BMS (Battery Management System): Monitor battery status to ensure safe operation.
  EMS (Energy Management System): Optimize energy scheduling to improve system efficiency.

Power flow: Power transfer between battery pack, PCS, load/grid. 
Communication data flow: Collaborative control between modules through data exchange.

2. Leakage hazards of energy storage systems

• 
  DC side leakage
  Short circuit between battery clusters, insulation failure: may lead to thermal runaway, causing fire.
  DC arcs are more difficult to extinguish than AC arcs, making them highly dangerous.
• AC side leakage
  Ground fault: may cause equipment damage or personal electric shock.

3.Detailed explanation of the risk points of DC side leakage

• Inside the battery
  Cell leakage: After the electrolyte leaks, a conductive path is formed between the high-voltage pole and the shell, generating leakage current.
  Diaphragm damage: Internal micro-short circuits form abnormal leakage current channels, which may cause thermal runaway.
• Battery module and battery cluster level
  Abnormal connection points: loose bolts and corrosion lead to increased contact resistance, burning insulation materials, and causing leakage to the ground.
  High-voltage cables and copper bars: After the insulation layer is damaged, the exposed conductor contacts the metal frame, causing leakage.
  BMS sampling harness: Contact with high-voltage components after insulation damage may result in BMS paralysis or fire.
• Battery system level
  Coolant leakage: Coolant leakage forms a conductive bridge, causing insulation to drop or short circuit.
  Dust and condensation: Dust and water vapor mix to form a conductive film, reducing insulation resistance and causing creepage.
  Installation and maintenance issues: Tools left behind or accidentally come into contact with live parts, directly causing short circuits and leakage.

Comparison of technical solutions for energy storage leakage monitoring

In order to deal with the above risks, in addition to using redundant insulation and fault isolation measures in the design stage, insulation resistance testing and real-time leakage current monitoring need to be strengthened. The following is a comparison of common leakage monitoring technical solutions:

Conclusion: The fluxgate technology is more suitable for the strict monitoring of small leakage current in energy storage system because of its high precision and fast response characteristics. CHIPSENSE made a series of fluxgate current sensors for this needs.

Technical characteristics of fluxgate leakage current sensor

The fluxgate leakage current sensor adopts high-frequency fluxgate technology, which can realize micro-ampere leakage current monitoring and is suitable for DC side insulation fault detection of electrochemical energy storage systems. Its core advantages include:

• High accuracy: The measurement range covers ±15 mA to ±300 mA, with an accuracy of ± 0.5%.
• Low temperature drift: Zero temperature drift is only ± 1.5 mV/K, suitable for complex environments.
  Quick response: response time of 500 ms, timely detection of faults.
  High reliability: insulation voltage 3 kV, in line with IEC 60664-1:2020 and other international standards.

Typical applications and parameter examples

Typical application scenarios
Battery stack insulation fault detection: prevent thermal runaway caused by DC side short circuit.
DC bus leakage monitoring: ensure the safe operation of the system.
Example of technical parameters
Supply voltage: ± 12 V~ ± 15 V
Rated range: ± 10 mA to 300 mA
Measuring range: ± 15 mA~ 360 mA
Operating temperature: -40 ° C~ 70 ° C
Theoretical gain: 500 V/A
Linearity: 0.5%

Conclusion

Insulation faults and leakage are major hidden dangers for the safe operation of energy storage systems. By adopting high-precision monitoring technologies such as fluxgate leakage current sensors, real-time monitoring of tiny leakage currents can be realized, faults can be detected and dealt with in time, and thermal runaway and fire accidents can be effectively prevented. In the design and operation and maintenance of energy storage systems, redundant insulation design, environmental control and high-precision monitoring technologies should be combined to build a multi-level safety protection system. 
CHIPSENSE fluxgate leakage current sensor provides customers with safety and convenience.

CHIPSENSE is a national high-tech enterprise that focuses on the research and development, production, and application of high-end current and voltage sensors, as well as forward research on sensor chips and cutting-edge sensor technologies. CHIPSENSE is committed to providing customers with independently developed sensors, as well as diversified customized products and solutions.

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