Low Resistance Measurement

In general the resistance of components used to control circuits such as switches and relay contacts starts out very low and increases over time due to factors such as wear and dirt.

Low resistance measurement.

An instrument for measuring resistance is called an ohmmeter. This handbook gives an overview of low resistance measurement techniques explains common causes of errors and how to avoid them. Low resistance measurement method. A low resistance measurement is typically a measurement below 1 000 ohm.

This handbook gives an overview of low resistance measurement techniques explains common causes of errors and how to avoid them. It is common to provide 4 wire connections to current sensing shunt resistors of low resistance operating at high current. In the above picture r is the unknown resistor and v is a multimeter set to read millivolts. The higher the resistance the lower the current flow and vice versa.

Cropico is a world leader in low resistance measurement. Basically the trick is to pass a stable known amount of current through the low value resistor and measure the voltage drop across it. Requires a regulated power source such as 5v a low temperature coefficient 220 ohm resistor and a multimeter with ohm voltage and millivolt measurement mode. We have also included useful tables of.

We produce a comprehensive range of low resistance ohmmeters and accessories which cover most measurement applications. What does the low resistance measurement tell the operator. Obviously the multimeter is connected permanently as shown in picture. The two coils are at right angles to each other and are free to rotate about the common axis.

Why measure resistance to determine the condition of a circuit or component. Simple ohmmeters cannot measure low resistances accurately because the resistance of their measuring leads causes a voltage drop that interferes with the measurement so more accurate devices use four terminal sensing. The practical unit is the ohm. Also at this level standing voltages across the item being measured e g.

It comprises of a permanent magnet similar to that of a pmmc instrument and two coils in between the magnetic field created by the poles of the magnet. We produce a comprehensive range of low resistance ohmmeters and accessories which cover most measurement applications. The low resistance measurement will indicate to the observant. At this level it is important to use test equipment that will minimize errors introduced by the test lead resistance and or contact resistance between the probe and the material being tested.

The technique is commonly used in low voltage power supplies where it is called remote sensing to measure the voltage delivered to the load independent of the voltage drop in the supply wires. How to measure low resistances below 1 ohm such as cables current sense resistors switches relays and model rocket igniters.