I. Product Classification
(1) Classification by Technical Principle
DC Voltage Drop Method (Four-Wire Method / Kelvin Method) Tester
Principle: It uses the four-terminal measurement method, applying a stable DC current (usually ≥100A) to the circuit under test and calculating the resistance value by measuring the voltage drop.
Features: High measurement accuracy, effectively eliminating the influence of test lead resistance and contact resistance, it is currently the most widely used testing method.
AC Method Tester
Principle: It uses an AC power source to complete the measurement.
Features: Less commonly used for measuring the contact resistance of circuit breakers, its measurement accuracy for inductive loads is lower than that of the DC method, and its application range is relatively limited.
(2) Classification by Function and Performance
Standard High Current Type
The output current can be stably set at 100A, 200A, 300A, or even 600A, specifically designed for precise measurement of micro-ohm level resistances. It is the standard configuration for preventive tests of high-voltage circuit breakers.
Multi-Function Integrated Type
In addition to loop resistance testing, it also integrates functions such as ground resistance testing, insulation resistance testing, and soil resistivity testing. It is suitable for comprehensive testing scenarios where a single instrument is required for multiple uses.
Handheld / Portable Type
Compact in size and lightweight, it usually comes with an internal lithium battery, making it suitable for on-site inspections, outdoor operations, and environments with limited space, such as testing of distribution cabinets and ring main units.
(3) Classification by Technological Improvements
Intelligent Type
Equipped with a large touch screen, it supports functions such as data storage, USB data transfer, Bluetooth communication, and thermal printing.
Specialized Improved Type
Designed for specific complex equipment such as GIS, it adopts wireless transmission technology to solve the problems of cumbersome grounding wire installation and removal, low efficiency, and high risk in traditional testing.
II. Main Application Scenarios
Power Switchgear Testing
Measuring the contact resistance between the moving and static contacts of various high-voltage, medium-voltage, and low-voltage circuit breakers, disconnectors, and load switches. This is the core application and directly affects the current-carrying capacity and operational safety of the switch.
Busbar and Connection Point Inspection
Detecting the contact resistance at the connection points of large current busbars and equipment terminal lugs in substations and factory distribution devices to prevent overheating faults caused by poor connections.
Cable Line Inspection
Measuring the DC resistance of high-voltage cables and verifying the connection quality of cable intermediate joints and terminal joints.
Other High Current Loop Measurements
Applicable to all scenarios requiring precise measurement of micro-ohm level resistances, such as resistance at welding points and motor winding resistance.
III. Key Points for Selection
(1) Clarify the Test Object
High-Voltage Switches: Instruments with a test current of ≥100A and a resolution of 0.1μΩ should be selected to accurately reflect the actual state of the contacts.
Low-Voltage Equipment: A test current of 50A–100A is usually sufficient, and the resolution requirement can be appropriately reduced.
(2) Evaluate Functional Requirements
Basic Functions: Automatic range switching, over-temperature/over-current protection, and automatic discharge upon test completion are essential functions.
Advanced Functions: If data analysis and report generation are required, models with large-capacity data storage, USB/Bluetooth data transfer, and automatic temperature compensation should be chosen; in outdoor environments with strong interference, the instrument’s anti-interference capability should be given priority.
(3) Consider the Usage Environment and Portability
Multi-site Mobile Operations: Handheld or portable instruments should be preferred.
Laboratory or Fixed Location Use: Instruments with more comprehensive functions and intelligent features can be selected.
(4) Verify Compliance and Budget
Compliance: Ensure the product complies with relevant core standards such as DL/T 845.4 and JJG 1052.
Budget: Different products vary in terms of cost-effectiveness, accuracy, and durability. A comprehensive selection should be made based on usage requirements and budget.
Post time: Mar-18-2026