The terms "micro-ohmmeter" and "contact resistance tester" are sometimes used interchangeably because both are designed to measure very low resistance values. However, there are differences between them in terms of application focus, design features, and specialized functions:
1. Primary Purpose and Application
- Micro-ohmmeter: This device is generally used to measure very low resistance values in a variety of applications, such as testing cables, conductors, welded joints, circuit board connections, and general low-resistance electrical connections. Its focus is on precise low-resistance measurement.
- Contact Resistance Tester: Specifically designed to measure contact resistance in electrical connections, especially in high-power applications like circuit breakers, switchgear, busbars, and other connections in power systems. It’s typically used for assessing the integrity of contact points in high-current circuits.
2. Measurement Current and Accuracy
- Micro-ohmmeter: Typically offers a wide range of test currents, from a few milliamps to higher currents depending on the model. However, the current is often lower than that of a contact resistance tester. Micro-ohmmeters are very precise, making them suitable for low-power or small-scale applications.
- Contact Resistance Tester: Generally uses higher test currents, often above 10A and sometimes reaching up to 100A or more. This high current allows it to better simulate the real operational conditions of high-power connections, ensuring accurate results that reflect the resistance under load.
3. Resistance Range and Display Resolution
- Micro-ohmmeter: Can measure very small resistance values with high resolution, often down to micro-ohms (µΩ) or even nano-ohms (nΩ), depending on the model. Micro-ohmmeters are more versatile for applications needing ultra-low resistance measurements outside of contact points.
- Contact Resistance Tester: Also measures very low resistance values, but the range is usually focused on the resistance values relevant to contacts and high-power connections, which are often in the micro-ohm range.
4. Special Features
- Micro-ohmmeter: Often has general features like four-wire (Kelvin) measurement for accuracy, along with data logging and averaging functions for stable readings. It may also include automatic temperature compensation and other features beneficial for sensitive low-resistance measurements.
- Contact Resistance Tester: May include specific features such as high-current injection, automatic polarity reversal to prevent errors from thermal EMF, and may be designed to measure contact resistance under specific load conditions to simulate real-life operation of high-power equipment.
5. Typical Users and Environments
- Micro-ohmmeter: Used by professionals in electronics, electrical engineering, and manufacturing, where precise measurement of low resistance is needed, but not necessarily in high-current applications.
- Contact Resistance Tester: Primarily used by power utilities, industrial maintenance teams, and those involved in the testing and maintenance of power distribution equipment where high-current connections are critical.
The difference between a micro-ohmmeter and a contact resistance tester
While both devices measure low resistance, a micro-ohmmeter is versatile and useful for a broad range of low-resistance applications, while a contact resistance tester is specifically tailored to measure the resistance at contact points under high current. For power distribution and high-current applications, a contact resistance tester is usually the better choice, while for general low-resistance testing, a micro-ohmmeter is more versatile.
Contact resistance tester TEHL Series outputs DC 600A/400A/200A/100A current to test the contact resistance of circuit breaker or high current cable contacts. It is designed according to IEC62271. The main application of the tester is the measurement of circuit breaker contact resistance.
Nov 14,2024
