Low Resistance Measurement

What does the low resistance measurement tell the operator.

Low resistance measurement.

How to measure low resistances below 1 ohm such as cables current sense resistors switches relays and model rocket igniters. We produce a comprehensive range of low resistance ohmmeters and accessories which cover most measurement applications. It is an electromechanical instrument used for measurement of low resistances. A low resistance measurement is typically a measurement below 1 000 ohm.

Low resistance measurement method. Cropico is a world leader in low resistance measurement. The two coils are at right angles to each other and are free to rotate about the common axis. The higher the resistance the lower the current flow and vice versa.

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. Resistance r is the property of a circuit or element that determines for a given current the rate at which electrical energy is converted to heat in accordance with the formula w i2r. We produce a comprehensive range of low resistance ohmmeters and accessories which cover most measurement applications. Why measure resistance to determine the condition of a circuit or component.

In the above picture r is the unknown resistor and v is a multimeter set to read millivolts. 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. 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 practical unit is the ohm. This handbook gives an overview of low resistance measurement techniques explains common causes of errors and how to avoid them. The low resistance measurement will indicate to the observant. Obviously the multimeter is connected permanently as shown in picture.

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. An instrument for measuring resistance is called an ohmmeter. Also at this level standing voltages across the item being measured e g. Cropico is a world leader in low resistance measurement.

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. 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.