AC clamp meter measuring current standard
In lines with large currents, clamp ammeters are generally used for measurement, which is safer;
First, set the multimeter to the current range, and then connect it in series to the circuit of the current to be measured. It should be noted that if it is a DC circuit, pay attention to the polarity. Whether you are measuring current or voltage, you must adjust the meter to the corresponding gear, that is, the meter's gear should be higher than the voltage or current value of the object being measured. If not known, adjust to maximum value.
When measuring current, the ammeter must be connected in series with the load, because the current in the series circuit is equal everywhere, so the current passing through the ammeter is the load current to be measured. If it is connected incorrectly, it is connected in parallel with the load. Because the internal resistance of the ammeter is very small, a larger current will flow under the voltage of the load, causing damage to the ammeter.
When measuring voltage, the voltmeter needs to be connected in parallel with the load, because in a parallel circuit, the voltage in any branch is equal, that is, the voltage at both ends of the voltmeter is the actual voltage of the load. If the meter is inserted into the load circuit, it cannot be measured. actual voltage.
The structure of the clamp ammeter is actually an AC current transformer. It is equivalent to a transformer with only one primary turn and many secondary turns. The secondary load is the previous AC ammeter.
When the clamp ammeter clamps into a phase line, it is equivalent to having a primary winding. At this time, the operating current induces magnetic flux in the core circuit of the clamp ammeter. The magnetic flux passes through the secondary winding, induces a secondary voltage and forms a current in the secondary load. The size of this secondary current is proportional to the primary current, so the value indicated by the meter can indirectly reflect the size of the primary working circuit current. So it does not require breaking the circuit to measure current.
