AC clamp-on ammeter for measuring current as a standard
In lines with high currents, it is safer to use a clamp-on ammeter for general measurements;
First set the multimeter in the current gear, and then connect it in series in the circuit of the current to be measured can be. It should be noted that: if it is a DC circuit to pay attention to the polarity. Whether measuring current or voltage adjust the meter to the appropriate gear, that is, the meter should be higher than the voltage or current value of the measured object. Adjust to the maximum value when you don't know.
When measuring current, the ammeter must be connected in series with the load, because the current is equal everywhere in a series circuit, so the current through the ammeter is the load current to be measured. If connected incorrectly, it is connected in parallel with the load, because the internal resistance of the ammeter is very small, under the voltage of the load, it will pass a larger current, so that the ammeter is damaged.
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 tampered with the load circuit, the actual voltage cannot be measured.
The structure of the clamp-on ammeter is actually an AC current transformer. Equivalent to a number of turns only a turn, the number of turns of the secondary circle of many turns of the transformer, the secondary load for the last AC ammeter.
When the clamp-on ammeter is clamped into a phase line, it is equivalent to have a primary winding. At this point, the operating current in the clamp-on ammeter core circuit induces magnetic flux, magnetic flux through the secondary winding induces a secondary voltage and the formation of current in the secondary load. The size of the secondary current and the primary current is proportional to the value indicated by the meter head can indirectly reflect the size of the primary working circuit current. So it does not need to disconnect the circuit to measure the current.
