The structure of the measuring current section of a clamp type multimeter
The current measurement part of a clamp type multimeter consists of a current transformer and the current measurement part of a multimeter.
The iron core of the transformer has a movable part and is connected to the handle. When in use, press the handle to open the movable iron core. Place the wire of the measured current into the clamp, release the handle, and close the iron core.
At this point, the wire passing through the current is equivalent to the primary winding of the transformer, and the secondary winding will experience induced current, which is determined by the working current of the wire and the ratio of winding turns.
The Ammeter is connected to both ends of the secondary winding, so the current it indicates is the current in the secondary winding, which is proportional to the current in operation.
Therefore, the reduced scale is taken as the current quantity reflecting the primary side. When there is current in the conductor, the pointer of the Ammeter connected to the secondary winding will deflect proportionally, thus indicating the value of the measured current.
When using, turn the range switch to the appropriate current position. Hold the watch body in hand and press the switch with your thumb to open the pliers and guide the measured wire into the center of the iron core.
Then, by releasing the switch, the iron core will automatically close, and the current of the measured wire will generate alternating magnetic lines in the iron core. The current value is reflected on the meter and can be directly read.
1. Before using a digital multimeter, it is necessary to carefully read the user manual to familiarize yourself with the power switch function, limit conversion switch, input jack, user jack, and the functions of various function keys, knobs, and accessories.
In addition, it is also necessary to understand the limit parameters of the multimeter, the characteristics of overload display, polarity display, low-voltage display and other signs display and alarm, and grasp the change rule of the Decimal separator position.
Before measuring, the probe should be carefully checked for cracks, the insulation layer of the lead wire for damage, and the position of the probe inserted correctly to ensure the safety of the operator.
Before each measurement, it is necessary to double check whether the measurement items and the limit switch are in the correct position, and whether the input socket (or dedicated socket) is selected correctly.
3. When measuring, the instrument may experience a skip phenomenon, and it should wait for the displayed value to stabilize before reading.
Although the digital multimeter has a relatively complete protection circuit inside, it is still necessary to try to avoid misoperation during operation, such as measuring voltage with a current gear, measuring voltage or current with a resistance gear, and measuring live capacitors with a capacitance gear, in order to avoid damaging the instrument.
If only the highest digit "1" is displayed and all other digits are hidden, it indicates that the instrument has overloaded and a higher limit should be selected.
6. It is prohibited to turn the limit switch when measuring a voltage above 10OV or a current above 0.5A to avoid arcing and burning the contacts of the transfer switch.
7. The number with a danger mark next to the input socket represents the limit value of the input voltage or current for that socket. Once exceeded, it may damage the instrument and even endanger the safety of the operator.
8. The clamp type multimeter shall not be used to measure the current of high-voltage lines, and the voltage of the tested line shall not exceed the voltage level specified by the clamp type meter (generally not exceeding 500 volts) to prevent insulation breakdown and personal electric shock.
9. Measurement should estimate the magnitude of the measured current, select an appropriate range, and do not use small range gears to measure large currents. 10. Before measurement, pay attention to turning the range switch to the corresponding AC current gear, and do not use voltage and resistance gears to measure current. Remember! Do not use resistance and current ranges to measure voltage, otherwise, if not careful, the meter may be burned.
11. Only one wire can be clamped in each measurement. When measuring, the measured wire should be placed in the center of the clamp to improve the accuracy of the measurement. It is best to level the watch body with your hands and try not to let the wires lean against the pliers and watch body.
12. After the measurement is completed, the range switch must be turned to the maximum voltage range position, and then the power switch must be turned off. To ensure safe use next time.
