As the name implies, the TC or the Dietze pliers are designed to measure the AC power in the circuit without breaking it. The principle of the current-measuring instrument is based on the principle of the simplest current transformer. In this case, the primary winding is a bus or cable with a measured current, and the secondary role is played by the clamping of the mites, inside which is located the second multi-turn winding, wound on a magnetic core made of ferromagnetic material. The alternating current in the wire( the primary coil) creates an alternating magnetic mole, the force lines of which pass through the secondary winding, exciting the EMF in it, in proportion to the current in the first coil. Thus, by measuring the emerging EMF, one can find the current strength in the first coil( wire).
design The current clamp-on clamps, regardless of the manufacturer and modifications, contain the following elements: magnetic circuits with movable clamp-lever, switch of measuring ranges, screen, output connectors for probes( in this case mites can be used as a normal multimeter) and a button for fixing current measurements(photo below).
Figure 1 - S-line TC DT 266 FT
Most modern current meters also include an internal transformer with a diode bridge. In this case, the terminals of the secondary winding are connected via a shunt. Depending on the range of measured currents, the current clamp can be single-handed( for voltages up to 1000 V) and two-handed with additional insulated handles( for voltages from 2 to 10 kV inclusive).The current measuring devices intended for measurements of more than 1 kV have an insulator length of less than 38 cm and handles of not less than 13 cm.
As a rule, the safety class and the maximum measured current are indicated on the body of the device. For example:
- CAT III 600 V - this means that the device is protected from short-term voltage surges inside the equipment when operating in fixed networks with voltages up to 600 V.
- CATIV 300 V - this means that the device is protected against voltage surges inside primary equipmentvoltage up to 300 V. An example of such equipment can serve as an ordinary electric meter.
Safety instructions for operation
The clamp meter can only be used in enclosed spaces or in open spaces in dry weather. The current can be measured both on insulated cables and on bare ones. Before using, a person should wear protective gloves, and put a dielectric base under their feet and wear special shoes.
Measurement procedure
As a rule, the use of current clamp is not particularly difficult. Before using the tool, it is worth paying great attention to safety techniques, as was mentioned earlier. 
How to use the clamp meter correctly:
- Set the desired range on the switch.
- Press the button to uncover the magnetic circuit.
- Circle single conductor in AC or DC network( if supported by the device).
- Position the current clamp perpendicular to the direction of the wire.
- Read the display.
Often the difficulty of using current-measuring devices is to isolate a single conductor: when trying to read from a normal cable coming from the outlet, zero should appear on the screen. This is because the currents of the phase conductor and the neutral conductor are equal in magnitude and opposite in direction. Consequently, the magnetic flux created by them is mutually compensated. If the current readings are different from zero, then this indicates a leakage current in the circuit, the value of which is equal to the value obtained. Therefore, for measurements it is necessary to find a place where the wires separate and separate a single core. As such a place, you can use a switchboard or the place of connecting the phase wire to the circuit breaker. Nevertheless, this can not always be done, which limits the scope of the current clamp.
If a unit is displayed during the measurement, this indicates that the current value in the wire is outside the measuring range. In this case, it is necessary to increase the range of current measurements with a switch. When performing measurements in hard-to-reach places, you can use the Hold button. With its help, you can fix the result of the last measurement and see it by removing the mites. Pressing Hold a second time, you can reset the value.
You can visually see how to operate the current clamp, you can on the video instructions below:
tool Useful "trick"
If you want to measure a small value of the current, you need to make several turns of wire on an open magnetic circuit, and set the range switch to minimum. After that it is necessary to take readings, and to determine the actual value, divide the obtained number by the number of wound turns.
Example of using
Here is an example of how to use a clamp meter when measuring load in a 220 V network, for example in an apartment. In this case, the switch must be set to the position of AC 200. Next, use a current clamp to grab the insulated conductor and take readings. After that, the obtained value of the current must be multiplied by the voltage in the network of 220 V. For example, if the device shows 5 A, the power consumption in the network will be P = U * I = 5 * 220 = 1100 W or 1.1 kW.The value obtained can be used to check the operation of electricity meters.
That's the whole instruction on how to use the current clamp yourself. As you can see, there is nothing complicated. The main thing is to observe security measures and carefully approach the measurements. We hope that our tips and a visual video instruction have explained to you the order of actions!
It will be interesting to read:
- How to use the multimeter - instruction for kettles
- How to check the correct operation of the meter
- The tool list of the electrician
