Extech Milli-Ohmmeter
Milli-Ohmmeters, or Milliohmmeters / Milliohm Meters, are designed to measure low resistance at high accuracy confirming the value and integrity of any electrical circuit and connection. These meters may be used to evaluate component or circuit resistance in PC board resistance in laboratories and research and design departments, motor winding opens and shorts, transformers, heating elements, contact resistances of switches and connectors or low resistance connections for bonding.
Features to Consider When Choosing Milliohm Meters
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Resistance Ranges
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Resolution
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Bench-Top
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Hand-Held Portable
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Digital Display Number of Counts
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Accuracy and Sensitivity
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Test Current
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Go / No-Go Alarms
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Four wire Kelvin Probes
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Manual or Auto-Ranging
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Temperature Compensation
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Interface Capability
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Memory Capability
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Over-temperature and over-voltage protection
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Enclosure IP rating
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Power Supply
Typical Applications for Milliohmmeters
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Printed Circuit Boards
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Capacitors
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Motor Coils
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Transformers
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Generators
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Relay Contacts
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Electrical Connections
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Cable Joints
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Earth Bonding Systems
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Electronics Board Component Resistance
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Electronic Control Components and Relays
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Compression Joints
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Switchboard and Substation Grounding and Wiring
It should be noted that when measuring resistance, there may be changes in final measurements based on the thermal effects of temperature. Please check the manufacturer’s manual for compensation or measurement considerations, especially when the product under test contains dissimilar metals.
What are Kelvin Probes and why are they important for measuring Low Resistance?
Micro-Ohmmeters and Milliohmmeters are commonly used with a 4-wire measurement system referred to as the Kelvin System.
A Kelvin System allows low resistance measurements to be taken without the influence of the measuring probes, leads, contact points, and wiring. This is a way of measuring continuity and bonding resistances ensuring all contact and lead resistances are compensated, which allows a much greater accuracy in final measurements. Four wire measurements using Kelvin Probes reduces the voltage drop in test leads that cause measurement inaccuracies, making them excellent for resistance measurements below 1 ohm.