Resistance measurement with a digital multimeter guide
Digital multimeter measuring resistance
A multimeter measures resistance by outputting a small current to a circuit. Standard units are ohms (Ω). Since current flows through all possible channels between the probes, the resistance reading represents the total resistance of all channels between the probes.
The resistance range of the multimeter has segmented ranges, such as Fluke 87V/C, and the electrical resistance range is 600.0 Ω, 6,000 kΩ, 60.00 kΩ, 600.0 kΩ, 6,000 MΩ and 50.00 MΩ. To avoid damage to the multimeter or the equipment under test, please turn off the power to the circuit and discharge all high-voltage capacitors before measuring resistance with the digital multimeter.
Steps to measure resistance with digital multimeter
1) Disconnect power from the circuit
2) Select the resistance range (Ω).
3) Plug the black test probe into the COM input jack. Plug the red test probe into the Ω input jack.
4) Connect the probe tip at both ends of the component or short-circuited section whose resistance is to be measured.
5) For readings, be sure to note the unit of measurement – ohms (Ω), kiloohms (kΩ) or megaohms (MΩ).
1,000 Ω = 1 kΩ 1,000,000 Ω = 1 MΩ
Make sure the power is turned off before taking resistance measurements.
Here are some tips for measuring resistance with a digital multimeter:
1) Because the meter's test current flows through all possible paths between the two probes, the resistance value measured on a resistor on a circuit is often different from the resistor's rated value.
2) When measuring resistance, the test lead will bring an error of 0.1 Ω to 0.2 Ω. If you want to measure the resistance of a wire, you touch the probe tips together and read the resistance of the wire. If necessary, you can use the multimeter's Relative Value (REL) mode to automatically subtract this resistance value. (For information on using the relative value function, please refer to the Fluke Multimeter Resource Website)
3) In the resistance setting, the voltage output by the meter is enough to turn on the forward bias of the silicon diode or transistor on the circuit. If in doubt, press C to apply a lower current at the next higher range. If the resulting value is larger, use the larger value. Continuity is a quick go/no-go resistance test used to differentiate between open and closed circuits.
