Kelvin clamps Manufacturers online

Kelvin clamps, also known as four-wire or 4-pole clamps, are a specialized accessory for measuring tools for the precise measurement of electrical resistance values and voltages.

They are mainly used where low resistances in the milliohm or microohm range need to be measured, for example in electronics production, battery tests, contact resistance measurements or quality control of conductors and connections.

Below you will find the functionality and types of Kelvin clamps, their areas of application and their advantages:

How Kelvin clamps work:

The mode of operation is based on the so-called four-wire measuring principle (Kelvin measurement):

In a normal two-wire measurement, the measuring current flows through the same wires through which the voltage is measured. The line and contact resistances therefore distort the result.

Kelvin measurement, on the other hand, uses two separate conductor paths:

A current circuit conducts the measuring current through the component to be tested.

A voltage circuit measures the voltage directly at the contact points of the test object.

As no significant current flows in the voltage circuit, the influence of the line and contact resistances remains negligible.

The result is a highly precise, reproducible measurement of the actual resistance or voltage drop at the test object itself.

Types of Kelvin clamps:

1. Spring-loaded Kelvin clamps:
   Spring mechanisms ensure constant contact, even with repeated use in automated test stands.
   This variant ensures high reproducibility and low contact uncertainties.
2. Miniature Kelvin clamps:
   Compact designs for fine measuring points, e.g. on SMD components or thin cables.
   Frequently used in electronics development or calibration technology.
3. High-current Kelvin clamps:
   For applications where high currents need to be measured or supplied, such as battery cells, busbars or contacts in electromobility.
4. Special Kelvin clamps:
   Variants with gold-plated, pointed or insulated jaws for contacting coated, oxidized or difficult-to-access surfaces.

Use of Kelvin clamps:

1. Precision resistance measurement:
Measurement of very small resistances, e.g. of shunts, conductor tracks, connectors or welding points.

2. Battery and cell testing:
Testing of internal resistances of individual battery cells or rechargeable batteries in research, production and quality assurance.

3. Cable and conductor tests:
Checking contact resistances and conductivities of power cables, copper rails or contacts.

4. Electronics production and development:
Use in automated test systems (ATE) or laboratory measuring stations for accurate characterization of electronic components.

5. Calibration and laboratory applications:
Use in metrology and calibration technology to trace measured values to national standards.

Advantages of Kelvin clamps:

• Highest measurement accuracy: The four-wire principle fully compensates for lead and contact resistances.
• Repeatable measurement results: Constant contact pressure and stable contact ensure reproducible measurements, even with the smallest resistances.
• Versatility: Can be used for electrical, electronic and electromechanical components, cables, batteries and conductors.
• Time-saving: Fast contacting enables efficient series and laboratory tests without complex wiring.
• Durability: Robust materials, gold-plated contacts and precise mechanics ensure a long service life with frequent use.
• Safety: Low measuring currents and stable contacting minimize the risk of component damage.
• Compatibility: Easy integration into measuring systems, multimeters, micro-ohmmeters or automated test adapters.

Kelvin clamps are specialized measuring tools based on the four-wire measuring principle and eliminate the influence of lead resistance. As a result, they enable high-precision measurements of small electrical resistances - a decisive advantage in research, quality control and industry. Their most important advantages are maximum precision, repeatability, robustness and versatility, which makes them an indispensable part of modern electrical measurement technology.

Here are the most important aspects to look out for when buying Kelvin clamps:

In a professional environment - for example in laboratories, test departments, electronics production, battery development or cable testing - the quality, design and electrical properties of Kelvin clamps are decisive for the accuracy and reliability of the measurement results. When purchasing, a targeted selection based on technical and economic criteria is therefore essential.

• Before a selection is made, the requirements for measuring range, accuracy and environment must be precisely defined:
• How small are the resistances or voltage drops to be measured?
• What currents and voltages occur?
• In which environment will the measurements be taken - laboratory, production, harsh industrial environment?
• Are these manual individual measurements or automated series tests?
• What mechanical accessibility do the test specimens offer, large terminal points, fine conductor tracks, SMDs?
• A precise requirements analysis prevents incorrect purchases and ensures that the terminal blocks are suitable for the respective application.
• Spring-loaded Kelvin terminals: Provide constant contact pressure and uniform contacting - ideal for series measurements.
• Miniature Kelvin clamps: For precise measurements on small components, conductor tracks or SMD components.
• High-current Kelvin clamps: Developed for batteries, busbars and cables with high currents.
• Magnetic or screw-type Kelvin terminals: For stable, repeatable contacts in fixed test fixtures or harsh conditions.
• The choice depends on the component type, current range, contact geometry and the desired repeatability.
• The electrical quality of the terminals directly determines the measurement accuracy:
• Low contact resistance: Minimizes voltage losses and measurement errors.
• Separation of current and voltage paths: Must be mechanically and electrically precise.
• Shielding: Reduces interference from electromagnetic influences, especially for sensitive measurements.
• Conductive materials: High-quality metals such as gold-plated copper, beryllium copper or stainless steel ensure consistent contact quality.
• Voltage and current resistance: Clamps must be designed to be electrically safe for the measuring range.
• Spring pressure, clamping force and contact geometry should ensure a stable, repeatable hold without damaging the object being measured.
• Robust, corrosion-resistant materials extend the service life, especially with frequent use.
• Easy-grip shapes, insulation and flexible connection cables make handling easier.
• Compact designs are crucial for measurements on PCBs or in narrow test fields.
• Sufficient contact protection for measurements at higher voltages or in damp environments.
• Materials must withstand high ambient temperatures or intrinsic heat.
• Protection against corrosion caused by soldering flux, oils or chemicals in industrial environments.
• Standards and certificates such as IEC, CE or VDE certification as proof of quality and safety.
• Compatibility with existing measuring systems, e.g. banana plugs, BNC, screw connections, special adapters.
• Cable length and quality, shielding, flexibility and durability are crucial for signal stability.
• Terminals should be easy to install in automated measurement systems.
• Professional terminal blocks enable traceability to calibration standards for quality assurance.
• Manufacturers with expertise in measurement technology or test system integration often offer higher precision.
• Documented test protocols and calibration certificates increase traceability.
• Customized clamping forms or contact materials can increase measurement accuracy and service life.
• Spare parts, maintenance and support ensure long-term use.
• High-quality Kelvin clamps pay for themselves through reduced measurement errors and longer service life.
• Replaceable contacts or springs reduce follow-up costs.
• Standardized clamp types in test benches reduce logistics and training costs.
• Reduces re-measurements and reject rates, which improves process efficiency and product quality.

The purchase of Kelvin clamps requires a sound evaluation of measurement requirements, electrical precision, mechanical design, safety, compatibility and cost-effectiveness. High-quality Kelvin clamps guarantee precise, repeatable and trouble-free measurements - especially in applications with very small resistances, such as battery testing, conductor track checks or contact resistance measurements. Those who pay attention to material quality, measurement stability and long-term durability when making their selection are not only investing in precise measurement technology, but also in reliability, efficiency and product quality.

Kelvin clamps can be purchased from various suppliers. You will find comprehensive information on manufacturers and suppliers of Kelvin clamps around the world on Exportpages.