Current according to ohms law is the ratio of voltage to the resistor. This is the flow of election on the circuit, with s.I unit in Amper. Current Measurements using a multimeter is one of the best methods to measure current in a circuit. Current measurements make designing of circuits easy and accurate.
when Measuring a current in a circuit, the circuits must be open, while the ammeter passes through the open circuit in series or line with the circuits.
Meaning the ammeter must be connected to the path through which electrons flow in other to measure the current. The ammeter can be panel mounted or portable meter. Due to this post, we shall be using portable meters.
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DC Current measurements using analog multimeter.
To measure a DC Current using an analog multimeter the following procedures should be followed.
- Inserts the meter probes to the multimeter slots. The black probe to COM slots and the red probe to either mA or A depending on the current you are Measuring. When Measuring a high current connect the red probe to A and connect to mA when Measuring in a lower current.
- Set range selector knob to DC Current mode and also select the appropriate range you are Measuring. It is advisable to set the range to a higher range, so far it can be adjusted when Measuring. This is to prevent the meter from damaging when overloaded with current above the selected range.
- Turn OFF the circuit and safely remove the meter probes after measuring the current.
- switch OFF the circuit to be measure and break the circuit so that the meter will be connected in-line or series to the part where we want to measure current.
- Connect the red probe to the positive side or source and the black probe to the end side, completing the circuit. The meter will indicate a negative deflection when probes are connected in a revised manner.
- Turn ON the supply and optimize the range of the meter by lowering the range knob to obtain a maximum deflection.
AC current measurements using analog multimeter.
measuring AC using Analog multimeter almost the same with that of DC measurements. The difference between the two is not much.
The measurements of AC take the following procedures.
- inserts multimeter probes appropriately. The back probe to COM slot while the red probe goes to mA or A. Depending on the current Measuring if is high or low.
- set the range knob selector to AC current mode. Adjust to a higher range for current measurements.
- Connect the red probe to the source side and connect the second probe to another side of the circuit. Making the meter to be in series with the circuits.
- Turn ON the supply of the circuit and start the adjust the range knob for a maximum deflection of the pointer.
NOTE: when using an analog multimeter to make Measurements, always reset the pointer to zero value before starting your measurements. current Measurements using a digital multimeter
current Measurements using digital multimeter
digital multimeters are now widely used across the globe more than analog multimeters because of many advantages it posses against that of analog.
digital multimeter makes the measurements of instruments more simple and accurate compare to that of analog.
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Below are the advantage of a digital multimeter to analog;
- It displays the measured values in digital figures thereby eliminating error due to parallax.
- Some of the digital multimeter meters are auto range selector. For instance, when Measuring a voltage with the meter, all you need to do is to select the voltage mode. And the meter will measure the voltage not minding if is high or low voltage. it uses it has to select the range of what it’s Measuring.
Measuring DC and AC current using digital multimeter.
- get a digital multimeter and turn it ON.
- Connect the probes to the meter. Black to COM why red to A.
- Set the selector knob to AC or DC Current. depending on the one you are Measuring.
- Set the selector range to a higher range above the expecting value you are Measuring. For instance, when Measuring a current of 5A, I will place the knob to a range higher than the 5A. I can decide to select 10A or 20A on the meter current range.
- Break the circuit and connect the meter in series to the circuit. i.e using one probe to connect to source and the other probe to the circuit, Making the circuit a close loop. And meter being in series to the circuit.
- Power ON the circuit and the meter will start to display the amount of current flowing through the circuit.
Current measurement using a clamp meter multimeter
This is the most simple and easy method to measure current on a circuit. But due to sometimes not all multimeter has this feature makes it challenging. Nevertheless, when your meter doesn’t have a clamp feature on them, the following method discusses before should be used.
The following are ways to measure current using a clamp multimeter.
- Get a clamp multimeter and set the center knob to Amps(A). Considering whether is a DC or AC you want to measure. Set the knob to AC when measuring for AC and set to DC when measuring for DC. Perhaps some of the meters are automatic and can be used to measure both AC and DC so far the meter is set to be on amps (A).
- On the clamp meter is a button used in opening the clamp of the meter. When pressing the button the clamp on the meter tends to open.
- Press the button and pass it through the wire you want to measure the current flowing on then.
- Release your hand from the button and make the clamp close and the wire passing through the center of the clamp.
- The screen on the meter will display the amount of current flowing through the wire.
Note: when using the clamp, don’t clamp two wires at a time. Instead, clamp and measure them separately.