How to Reduce Leakage Current? — Application and Practice of LISUN WB267x Series Leakage Current Testers

1. Introduction
Throughout the entire life cycle of electrical equipment, leakage current is a key indicator for measuring insulation performance and safety level. In accordance with national and international standards such as GB 4706.1 “Safety of household and similar electrical appliances – Part 1: General requirements” and IEC 60335-1, the leakage current of various electrical products must be controlled within specified limits (e.g., ≤0.75mA for household equipment and ≤0.1mA for medical equipment). Excessive leakage current mainly stems from factors such as aging or damaged insulation materials, unreasonable circuit layout, insufficient creepage distance, and poor grounding.
As a R&D and manufacturing enterprise specializing in electrical safety testing equipment, LISUN has launched the WB267x series leakage current testers. With precise measurement capabilities, test modes simulating actual operating conditions, and product characteristics adapting to multiple scenarios, these testers have become core tools for identifying leakage hazards and guiding leakage current optimization (Product details: https:https://www.lisungroup.com/products/electrical-safety-tester/leakage-current-tester.html). Based on the application practice of this series of testers, this paper explores effective paths to reduce leakage current in depth, providing practical solutions for enterprises to improve product safety performance.

2. Core Parameters and Testing Principle of LISUN WB267x Series Leakage Current Testers
2.1 Core Technical Parameters
The LISUN WB267x series leakage current testers cover multiple models, adapting to the testing needs of electrical equipment with different powers and types. Their core parameters are shown in the following table:

2.2 Testing Principle
The core testing logic of LISUN leakage current testers is to simulate the actual operating state of electrical equipment: by applying a rated AC voltage to the Device Under Test (DUT), it mimics the electric field environment during normal operation of the equipment, while accurately monitoring the current value between the equipment shell and the grounding terminal — this current is the leakage current. The tester is equipped with a high-precision current sensor and a fast overcurrent protection module. When the leakage current exceeds the preset limit, it will immediately trigger an audible and visual alarm and automatically record test data, helping inspectors quickly locate leakage hazards.
Compared with traditional testing equipment, LISUN testers have three advantages: first, they support AC/DC dual-mode testing, adapting to the insulation characteristics of different types of equipment; second, the test time can be flexibly set (1~99s), meeting the different needs of mass production line testing and laboratory compliance verification; third, some models support remote control, which can be integrated into automated testing lines to improve testing efficiency.

3. How to Reduce Leakage Current? — Optimization Paths and Practices Based on LISUN Testers
3.1 Design Optimization: Iterate Circuit and Structural Layout Through Precise Testing
Excessive leakage current often originates from omissions in the design stage, such as insufficient creepage distance caused by unreasonable circuit layout and improper grounding path design. LISUN leakage current testers can quantify the leakage current values of different design schemes by simulating actual working conditions, providing data support for design optimization.
Taking small household appliances (e.g., rice cookers) as an example, if the creepage distance between the power cord and the shell is less than the standard requirement of 3mm, leakage is likely to occur. Testing different layout schemes with the WB2671A tester: when the creepage distance is 2.5mm in Scheme 1, the leakage current is 0.9mA (excessive); after adjusting the layout to increase the creepage distance to 3.5mm in Scheme 2, the leakage current drops to 0.3mA (compliant). In addition, optimizing the position design of the grounding terminal to ensure a short and straight grounding path can further reduce the shell leakage current — after grounding optimization of an LED ceiling light, the leakage current drops from 0.5mA to 0.15mA as tested by the WB2671B tester.
The core optimization measures in the design stage include: first, according to the test data of the tester, ensure that the creepage distance and electrical clearance between the high-voltage and low-voltage parts of the circuit, as well as between live parts and the shell, comply with standards; second, optimize the grounding system design, adopting single-point grounding or star grounding to reduce leakage current caused by ground loop interference; third, reasonably plan the filter circuit and select high-quality EMI filters to reduce parasitic leakage current caused by electromagnetic interference.
3.2 Material Selection: Screen High-Quality Insulation Materials Through Performance Verification
The performance of insulation materials directly determines the magnitude of leakage current. Inferior or aging insulation materials will lead to a decrease in insulation resistance and a surge in leakage current. LISUN leakage current testers can be used for the selection and verification of insulation materials. By applying a rated voltage to samples of different materials and testing their leakage current, materials with excellent insulation performance can be screened out.
Taking industrial transformers as an example, if ordinary epoxy resin is used as the winding insulation material, the leakage current at high temperatures (e.g., 60℃) can reach 0.8mA; after selecting high-temperature resistant modified epoxy resin, the leakage current drops to 0.2mA as tested by the WB2673A tester. For the power cords of household equipment, selecting PVC materials with flame retardant grade V0 and insulation resistance ≥100MΩ can reduce the leakage current by more than 40% compared with ordinary PVC materials.
The key principles for material selection are: first, verify the long-term insulation stability of materials through LISUN testers according to the equipment’s operating environment (temperature, humidity, voltage level); second, prioritize materials with low dielectric loss and high insulation resistance, such as polytetrafluoroethylene and modified epoxy resin; third, adopt double insulation design for key parts (e.g., high-voltage windings, power interfaces), and test the cooperative insulation effect of double insulation through testers to ensure that leakage current can still be controlled when a single insulation layer is damaged.
3.3 Process Improvement: Eliminate Production Defects Through In-Process Testing
Non-standard production processes, such as loose winding, virtual welding, and damaged insulation layers, will lead to excessive product leakage current. LISUN leakage current testers can be integrated into key processes of the production line for in-process testing to timely detect and eliminate process defects.
Taking the production of air conditioner outdoor unit motors as an example, inter-turn short circuits during winding will significantly increase leakage current. Introducing the WB2673B tester into the production line for online testing: apply 3500V AC voltage to each motor, test the leakage current, and determine it as unqualified if the value exceeds 0.75mA, then return it for rework. Through this method, the unqualified rate of a motor factory has dropped from 5% to 0.8%. In addition, the optimization of welding processes is also crucial — replacing manual welding with automatic welding can reduce virtual connections and burrs at welding points. After process improvement of a washing machine motor, the leakage current drops from 0.6mA to 0.25mA.
The core measures for process improvement include: first, conduct 100% online testing with LISUN testers after key processes such as winding, welding, and assembly to timely reject unqualified products; second, standardize the production environment, control the workshop humidity ≤60%, and avoid increased leakage current caused by moisture absorption of insulation materials; third, strengthen the training of operators to avoid artificial damage to the insulation layer during assembly.
3.4 Inspection and Verification: Ensure Product Compliance Before Delivery Through Batch Testing
Factory inspection is the last line of defense to control excessive leakage current. With efficient testing speed and precise measurement capabilities, LISUN leakage current testers are suitable for mass production line testing, ensuring that the leakage current of each product meets standard requirements.
A medical diagnostic equipment manufacturer uses the WB2672A tester for factory inspection. The equipment needs to meet the GB 9706.1 standard, with a leakage current limit of 0.1mA. The tester applies 8000V AC voltage to the power part of each device for 30s testing, records the leakage current value, and automatically determines whether it is qualified. Through this testing process, the enterprise has achieved 100% compliance of leakage current of factory products, and the market complaint rate has dropped by 90%.
The optimization schemes for batch testing include: first, select the appropriate LISUN tester model according to the product type (e.g., WB2671A for small electronic components and WB2673A for large industrial equipment); second, set a reasonable test time (10~30s for conventional products and 30~60s for high-voltage equipment) to balance testing efficiency and accuracy; third, use the data analysis function of the tester to count the leakage current distribution of batch products. If there is an abnormal fluctuation, timely trace back the problems in the design, material, or process links.

4. Conclusion
Controlling leakage current is a core requirement for the safety and compliance of electrical equipment, and precise testing is a prerequisite for reducing leakage current. By simulating actual working conditions and accurately measuring leakage current values, the LISUN WB267x series leakage current testers provide data support for design optimization, material selection, process improvement, and factory inspection, becoming key tools for enterprises to reduce leakage current and improve product safety performance.
Practice has proved that through the whole-process control of “data-driven optimization in the design stage, performance verification in the material stage, in-process testing in the process stage, and batch screening in the factory stage”, combined with the precise testing capabilities of LISUN testers, the leakage current of electrical equipment can be effectively controlled within standard limits, and even reduced by more than 50%. In the future, as electrical equipment develops towards high voltage, miniaturization, and intelligence, the testing and control of leakage current will face higher requirements. LISUN series testers will also continue to iterate and upgrade, providing more comprehensive solutions for electrical safety testing.