Product Overview & Applications

Product Overview

The HM6090-200A Portable Contact Resistance Tester is a high-precision, handheld instrument designed for a critical maintenance task: accurately measuring the electrical resistance of high-current connections in electrical power equipment. Its primary function is to perform what is commonly known as a "Ductor Test."

This tester is an essential tool for predictive and preventive maintenance programs in utilities, industries, and infrastructure facilities. Its core purpose is to identify potential points of failure beforethey cause costly downtime, equipment damage, or safety hazards.

Test current is DC 100A, 200A. In the case of DC 100A, 200A can be directly measured contact resistance test results with a large-screen LCD display, and with data storage, print, time settings and other functions, and another gear 50A, 150A for user selection; custom test time, maximum 599S, much larger than the standard requirements of 60S; resolution 0.01μΩ and very stable. Meet the power; the electricity sector on-site high voltage switch maintenance and high-voltage switch factory contact resistance testing requirements.

Features & Advantages

High current: continuously output high current , effectively breakdownoxidation film on switch contact..
Strong anti-interference ability: Even under severe interference condition,last bit of data can be stable within +1 word.With highest resolution of 0.01 mu Q.
High accuracy: Measure system automatically switches the measuring range according to the signal due to its High-Performance CPU design, then possible to ensure the accuracy of test result .
Test current optional: The current can be freely selected from 50A, 100A 150A and 200A, and the test time can be arbitrarily set within 5S-59.
It can communicate with computer through RS232 serial port (9 pins)or USB cable, and upload data into computer .
The measurement data can be saved in real time, and the measurement results can be print out .

Additional Information

Item No.	Description	Qty	Unit	Notes / Purpose
1	HM6090-200A Main Unit	1	Pc	The central tester with display and internal battery.
2	Power Adapter / Charger	1	Set	Input: 100-240V AC, 50/60Hz. For charging the internal battery.
3	Four-Wire Kelvin Test Leads	1	Set	The most critical component. Includes 4 heavy-duty cables: 2x Current (C1, C2) and 2x Potential (P1, P2), each with large, insulated clamps.
4	Safety Grounding Cable	1	Pc	Heavy-duty cable with a large clamp for connecting the tester to earth ground. Essential for safety.
5	USB Cable	1	Pc	For data transfer to a PC (if supported by the model).
6	Documentation Pouch	1	Set	Contains the items listed below.

Maintenance FAQs

Q: What is the typical resistance range you measure, and why is micro-ohm (µΩ) resolution important?

A: The tester measures typically from 0.1 µΩ to 2 mΩ. Healthy contacts in high-current equipment have resistances in the micro-ohm range. Even a small increase-for example, from 20 µΩ to 50 µΩ-can indicate significant contact erosion, loosening, or contamination that will lead to dangerous overheating under load. Standard multimeters cannot measure these low values accurately.

Q: The tester is heavy. What's the safest way to connect it to a high-voltage circuit breaker?

A: Safety First: Ensure the breaker is fully isolated, de-energized, and grounded.

Position First: Place the tester on a stable, dry surface near the breaker. Do not try to hold the tester while connecting leads.

Connect Leads on Ground: Connect all four Kelvin clips to their respective test leads while on the ground.

Attach to Breaker: Then, carefully attach the clips to the breaker's primary terminals. The heavy Current (C) clips should be on the outside, and the smaller Potential (P) clips should be on the inside, directly on the contact points.

Q: The test aborts immediately with an "Open Circuit" or "Over Current" error. What should I check?

A: Open Circuit: Check that the circuit breaker contacts are fully closed. Check that all four test clips are making firm, clean contact with bare metal.

Over Current: This often indicates a poor connection that creates a high-resistance point, causing the tester's electronics to fault. Clean the contact points on the breaker and ensure your clips are tight.

Q: : The test leads and clips become quite hot during a 200A test. Is this normal?

A: It is normal for them to become warm due to the high current (I²R heating in the leads themselves). However, if they become hot to the touch, this indicates a problem:

High Resistance Connection: The most common cause is a dirty or loose connection at the clip. This creates a localized hot spot.

Action: Stop the test immediately, allow the clips to cool, and clean and reattach them securely.

Q: What is the recommended calibration interval, and why is it so important for a 200A tester?

A: Annual calibration is strongly recommended. Because the tester measures extremely low resistances with high current, any drift in its current source or voltage measurement circuitry will have a significant impact on the calculated resistance. Regular calibration ensures your measurements remain traceable to national standards and your maintenance decisions are based on accurate data.

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