What precautions should be taken while measuring the resistance in a series circuit using a DMM?

What precautions should be taken while measuring the resistance in a series circuit using a DMM?

Never apply power to the circuit while measuring resistance with a multimeter. Connect the multimeter in series with the circuit for current measurements, and in parallel for voltage measurements. Be certain the multimeter is switched to ac before attempting to measure ac circuits.

How is a DMM connected to a circuit to measure resistance?

When working on a circuit board, it may be necessary to lift one of the leads of the resistor from the board to measure the correct resistance of the resistor. The resistance measurement displayed by a digital multimeter is the total resistance through all possible paths between the test lead probes.

When using a DMM to measure resistance the leads should be?

The meter should display zero or a very small amount of resistance for the test leads. With the leads apart, the meter should display OL or I, depending on the manufacturer. Connect the tips of the probes across the break in the component or portion of the circuit for which you want to determine resistance.

What are the three general precautions to take when measuring resistance?

Precautions in Handling and Using a Meter

• Do not drop any meter.
• Do not overload any meter.
• Do not tamper with precision instruments.
• Before you connect a meter to a circuit, ensure that the range switch is set to an appropriate position.
• Carefully check circuit connections before applying power to meters.

Can you measure resistance in live circuit?

You can measure the voltage and the current of a live circuit and use those figures to calculate the resistance (Ohm’s Law), but you can’t actually measure the resistance of a live circuit. For a number of reasons, you need to turn the power off and measure the resistance of individual pieces of the circuit.

What is maintenance activity on a multimeter?

Proper use of Multimeter (OR) Multimeter Maintenance Guide: Calibrate the multimeter at frequent intervals. Protect the instrument from dust, fumes, moisture and heat. Renew ohmmeter batteries. When checking the resistance of the circuit, make sure the switch off the power to the circuit.

How is resistance measured on a digital multimeter?

The resistance measurement displayed by a digital multimeter is the total resistance through all possible paths between the test lead probes. Caution is required when measuring resistance across a component that is part of a circuit.

How do you set resistance on read probe?

You only need to change which socket the read probe lead plugs into if you need to measure current. Turn the big rotary dial to the setting for resistance, which is the one with the Omega symbol (Ω). If you don’t have an autoranging meter, select the most sensitive resistance setting.

Can you measure the resistance of a circuit?

You can measure the voltage and the current of a live circuit and use those figures to calculate the resistance (Ohm’s Law), but you can’t actually measure the resistance of a live circuit. For a number of reasons, you need to turn the power off and measure the resistance of individual pieces of the circuit.

What causes the resistance of a circuit to decrease?

Other factors that can affect resistance readings: Foreign substances (dirt, solder flux, oil), body contact with the metal ends of the test leads, or parallel circuit paths. The human body becomes a parallel resistance path, lowering total circuit resistance.