Electrical pincers are focused on measuring the corresponding characteristics (phase angle, voltage, power, current, etc.). In this case, the working circuit does not break and its functioning is not disturbed. There are voltmeters, ammeters, phase meters and tick-type power meters.
General information
Among the type of instruments under consideration, the most common are electric clamps for measuring current (ammeters of variable value). Their main purpose is the operational measurement of the corresponding value in the conductor element, without interrupting its operating state. These devices are used in systems up to 10 kilowatts.
Elementary electric clamps for alternating current operate according to the transformer principle, with one turn and primary bus winding. The secondary layer is a multi-turn analog placed on a detachable magnetic wire to which an ammeter is connected.
Principle of operation
To test the tire, the magnetic wire of the electric pliers opens under the force of the worker, who squeezes the insulating handles of the tool. The alternating current passing through the line in the coverage part transfers to the magnetic circuit a working stream induced by an electromotive force in the secondary configuration winding. A current is created in its confined space, its indicator is measured by an ammeter.
In modern versions of the devices under consideration, a circuit is used in which a rectifier and a current transformer are combined. This design involves connecting the terminals of the secondary with a set of shunts.
Types
Electrical measuring clamps are divided into two types:
- Single handle models for installations up to 1 kW.
- Analogs with a pair of knobs for systems from 2 to 10 kW.
In the first versions, the insulating compartment is also a handle. The wire magnet is opened using the lever of the push configuration. In two-handed versions, the insulating part in length is at least 380 millimeters, and the handle - from 130 mm. In the first group, control sizes are not provided.
The device in question consists of three blocks:
- A working element with a magnetic circuit, winding and meter.
- Insulating parts.
- Pens.
Application
Electrical pincers are also used in indoor installations or open systems (if the street is dry). Measurement work may be carried out on insulated elements (cable, wire segments, fuse holders) and on open parts (for example, tires).
The operator working with the tool must wear dielectric gloves while standing on an insulating mat. His assistant is located a little back and side, reading information from devices.
Modification C-20
Crimp clamps of the Ts-20 configuration are equipped with an open circuit magnetic circuit and a rectifier system. This device belongs to the transformer current group. Ticks C-20 make it possible to measure the value in the range from 0 to 600 A. At the same time, coverage is carried out on a wire element, the alternating current in frequency does not exceed 50 Hz.
In this modification, the “primary” is the current conductor itself, which provokes a variable in the closed space of the ferromagnet, which is transmitted to the secondary winding by means of the EMF, to which the electrical measuring device is connected.
The read current is directly proportional to the value in the tested conductor. It is counted on a dividing scale from 0 to 15 (if the switch lever is in position 15, 30, 75 A). Otherwise, the measurement is carried out on the lower ruler (from 0 to 300).
If you connect the clamps of the Ts-20 device with conductors to points of the circuit between which voltage is controlled, then you can track the AC voltage parameter up to 600 volts of a frequency of 50 Hz. In this case, the lever switch is moved to the "600 V" position when the "secondary" of the transformer is shorted.
Electric press tongs D-90
The design of this device includes a sliding magnetic circuit with a ferromagnetic part and a dynamic device. Product features allow you to read the characteristic of the active power without breaking the current circuit. The process itself is carried out by embracing the conductor and connecting another pair of analogs with plugs to the mains.
Actual voltage and current indicators measured by D-90:
- 220 and 380 V;
- 50 Hz;
- 150, 300, 500 A;
- 25, 50, 75, 100, 150 kW.
Calculations for measurements in the norm of 25-100 kW are carried out on the upper scale, the gradation of which is from 0 to 50, and from 75 to 150 kW, the gradation is from 0 to 150. The parameters are switched by plugs. One of them is placed in a special socket of the generator marked "*", the second - in a 220 or 380 V.
Correction of current limiting measurements is carried out using the switch lever, which is translated into one of six positions that are identical to the nominal voltage values and the investigated active power. The considered device allows the control of a similar parameter in circuits with three phases. To do this, through a magnetic circuit cover a linear wire. In this case, the voltage winding is connected to the desired phase or line.
In symmetric modes, you just need to take into account the power indicator of one phase, followed by its triple multiplication. In the opposite case (asymmetric), the corresponding capacities are checked in turn, according to the data of two or three instrument circuits. The resulting numbers are added in algebraic order. It is worth noting that the error parameter when using C-20 and D-90 does not exceed 4% of the available limit for different placement of teeth and conductor in the part of the magnetic wire.
How to use electric ticks?
In order to start work, perform the following steps:
- The desired range is set on the switch.
- Activate the key to open the magnetic wire.
- They encircle the working elements with an alternating or direct current conductor, depending on the type of device.
- Place the ticks perpendicular to the direction of the wire.
- Take data from the monitor.
Sometimes the complexity of the operation of the device is associated with the allocation of a single conductor. An attempt to take readings from a conventional cable that comes from a power outlet should be accompanied by a zero on the monitor. This action occurs because the phase and zero currents of the conductor are identical in magnitude and opposite in direction. With this in mind, the generated magnetic fluxes are mutually leveled.
In the case of non-zero current indicators, current leakage in the circuit is observed. Its parameter will be equal to the received value. In this regard, it is necessary for measurements to find the location of the separation of wires with the subsequent allocation of one core. Such a point can serve as a switchboard or a place for connecting the phase to the circuit breaker. A similar option is not always possible, which narrows the scope of application of electric ticks.
If a unit is visible on the display during measurement, this means that the parameter of the current strength in the wire goes beyond the limit of measurement. In this option, you need to increase the range using the switch. For work in hard-to-reach places it is recommended to use the Hold key. It will allow you to record the latest information that will be saved even after removing the tool. Pressing the button again resets the saved data.
Security measures
How to use electric tongs is described above. In addition to these safety measures regarding operator uniforms, several other factors should be considered. With intensive use of the device, its verification should be carried out at least twice a year. When purchasing a tool for home use, you should pay attention to the date of inspection by the manufacturer, available on a special stamp. It is recommended to work with a team of two people: one of them takes parameters, and the other records the values obtained.