Clamp Meter Knowledge Encyclopedia
Structural features of the clamp meter:
Clamp meters are usually used as AC ammeters, and there is a clamp head on the meter head. When measuring current, the clamp meter does not need to be connected to the circuit to be tested, just pass the power supply wire (only one) through the jaws, The current can be measured directly.
The clamp meter is mainly composed of a clamp head, a clamp trigger, a hold button, a function knob, a liquid crystal display, a test lead jack, and two red and black test leads. The clamp head is used to clamp the wire to measure the current, and the red and black test leads are mainly used to connect the clamp meter to measure the resistance and voltage.
The clamp head of the clamp meter is mainly used to clamp the wire under test when measuring AC current, and use the principle of current transformer to sense the wire current.
The clamp trigger of the clamp meter is mainly used to open and close the clamp head, the clamp head opens when pressed, and the clamp head closes when released.
The hold button of the clamp meter is mainly used to hold the measured data when testing the electronic circuit, so as to facilitate reading the recorded data.
The function knob of the clamp meter is mainly aimed at the multi-purpose characteristics of the clamp meter, and sets the corresponding range for different detections.
The LCD screen of the clamp meter is mainly used to display information such as detection data, data unit, and selected range.
The test lead socket is mainly used to connect the lead plug of the test lead and the insulation test accessories. Connect the red test lead to the VΩ jack, and the black test lead to the ground terminal.
How clamp meters work:
The working principle of the clamp ammeter is: based on the working principle of the current transformer, when the wrench of the clamp ammeter is held tightly, the iron core of the current transformer can be opened, and the wire of the measured current enters the inside of the jaw as a current mutual inductance primary winding of the device. When the core of the wrench is loosened and closed, an induced current is generated on its secondary winding according to the principle of the transformer, and the pointer of the ammeter deflects, thereby indicating the value of the measured current.
It is worth noting that: because the principle is to use the principle of the transformer, whether the iron core is tightly closed and whether there is a large amount of residual magnetism has a great influence on the measurement results. When measuring a small current, the measurement error will increase. At this time, the measured wire can be wound several times on the iron core to change the current ratio of the transformer to increase the current range.
Application of clamp meter:
Using Clamp Meters in Residential Applications:
For residential installation electricians, clamp meters are an essential tool for measuring loads on various branch circuits at the distribution panel. While a spot check of the current is often sufficient, sometimes this check does not provide a complete picture as the load is turned on and off, over several cycles, and so on. The voltage in an electrical system should be steady, but the current varies widely.
To check for peak or worst-case loading on a circuit, use a clamp meter with a min/max function designed for measuring high currents that exist for longer than 100 ms, or about 8 cycles. Designed. These currents can cause intermittent overload conditions that can cause nuisance tripping of the circuit breaker.
Measured on the load side of a circuit breaker or fuse. The circuit breaker will open the circuit in the event of an accidental short circuit. This is especially important for any type of direct contact voltage measurement. Even though the clamp meter's clamps are insulated and thus provide a level of protection not found in direct contact voltage measurements, caution is still required.
A common problem in electrical work in residential installations is mapping electrical outlets to circuit breakers. Clamp meters are very useful in identifying which circuit a particular receptacle is on. Start by getting a baseline reading of the circuit's existing current at the switchboard. Then, put the clamp meter in MIN/MAX mode. Go to the relevant outlet, plug in a load (ideally a hair dryer), and turn it on for a minute or two. Check to see if the maximum current reading on the clamp meter has changed. A hair dryer will typically draw 10-13 A, so there should be a noticeable difference. If the readings are the same, you are not using the correct circuit breaker.
