CN205692686U - A kind of current transformer - Google Patents

Abstract

The utility model relates to a current transformer. The shell (1) of the transformer is composed of an upper shell (1.1) and a lower shell (1.2). The lower shell (1.2) is provided with three secondary Outlet terminals (3), the upper casing (1.1) and the lower casing (1.2) are respectively provided with two primary cable holes (5) through which the primary cables pass, and the casing (1) There are two secondary coils (4), one secondary lead-out wire of one secondary coil (4) is connected to the first secondary lead-out terminal (3) of the lower casing (1.2), and the other lead-out wire is connected to The third secondary outlet terminal (3) of the lower casing (1.2), one lead wire of the other secondary coil (4) is connected to the second secondary outlet terminal (3) of the lower casing (1.2), and the other One lead-out line is connected to the third secondary lead-out terminal (3) of the lower casing (1.2). The utility model relates to a current transformer, which has the advantages of accurate measurement, fast and convenient installation, wiring and maintenance.

Description

a current transformer

technical field

The utility model relates to a current transformer, which is a current transformer convenient for measuring and protecting the motor of a screw air compressor, and belongs to the technical field of transformers.

Background technique

At present, most current transformers in the market can only measure single-phase current, and three current transformers need to be installed in a three-phase three-wire circuit, which has defects such as cumbersome installation and large space occupation; or adopt the " A three-phase integrated current transformer", or "a three-phase current transformer" disclosed in ZL 201610112285.7, which integrates three mutual induction coils in the same housing, although there is no need to install three independent current transformers, but It is still three transformers in essence, just integrated in one shell; at the same time, in the actual circuit, because the three-phase current vector sum is zero in the neutral point ungrounded system, it only needs to be installed The current of the third phase can be calculated from two phases, and none of the above measurement methods are reasonably designed according to this characteristic, so as to achieve the purpose of convenient measurement, simple installation and cost saving.

Contents of the invention

The purpose of the utility model is to overcome the above disadvantages and provide a current transformer with convenient measurement, fast and convenient installation/wiring/maintenance and small space occupation.

The purpose of this utility model is achieved in that:

A current transformer, the shell of the transformer is composed of an upper shell and a lower shell, the lower shell is provided with three secondary outlet terminals, and the upper shell and the lower shell are Two primary cable holes for the primary cables to pass through are respectively provided, and two secondary coils are provided in the housing, and the two secondary coils are respectively arranged correspondingly to the two primary cable holes;

For two secondary coils, one of the secondary lead-out wires of one of the secondary coils is connected to the first secondary lead-out terminal of the lower case, and the other lead-out line is connected to the third secondary lead-out terminal of the lower case, One lead-out wire of the other secondary coil is connected to the second secondary lead-out terminal of the lower casing, and the other lead-out wire is connected to the third secondary lead-out terminal of the lower casing.

The utility model relates to a current transformer. Two secondary coil sleeves arranged vertically are arranged between the upper casing and the lower casing, and the upper and lower openings of the secondary coil sleeve are facing the primary cable hole, and pass through the The primary cable of the primary cable hole is inserted into the secondary coil sleeve; the secondary coil is set on the secondary coil sleeve.

The utility model relates to a current transformer. The outer top of the lower housing is provided with three secondary connection terminal slots, and the three secondary connection terminals are respectively embedded in the three secondary connection terminal slots.

The utility model relates to a current transformer. The secondary connection terminals are provided with M3 threaded holes, and the secondary connection terminals are respectively screwed with M3 pressing screws.

The utility model relates to a current transformer. The outer bottom of the upper housing is provided with screw installation holes, and the outer bottom of the lower housing is provided with screw installation holes.

Compared with the prior art, the beneficial effects of the utility model are:

The utility model measures the two-phase circuits at the same time, and calculates the third-phase current through the characteristic that the vector sum of the three-phase currents in the neutral point ungrounded system is zero, so it not only simplifies the transformer structure, reduces the cost, and It makes the early installation and later maintenance simpler and more convenient; at the same time, the utility model can be conveniently installed on the bottom plate through the screw mounting holes at the bottom of the shell, so the installation is extremely convenient; the lead-out is realized through three secondary outlet terminals, greatly It reduces the cumbersomeness of transformer wiring and makes its connection more convenient.

Description of drawings

FIG. 1 is a schematic diagram of a three-dimensional structure of a current transformer of the present invention.

FIG. 2 is an exploded view of FIG. 1 .

Fig. 3 is a front appearance view of a current transformer of the present invention.

Fig. 4 is a schematic diagram of the internal structure of a current transformer of the present invention.

Fig. 5 is a schematic diagram of a secondary coil slot of a current transformer housing of the present invention.

Fig. 6 is a schematic diagram of a current transformer shell screw mounting hole of the present invention.

Fig. 7 is a schematic diagram of a secondary outlet terminal slot of a current transformer of the present invention.

Fig. 8 is a schematic diagram of a secondary outlet terminal of a current transformer of the present invention.

Fig. 9 is a schematic diagram of a secondary outlet terminal identification of a current transformer of the present invention.

Fig. 10 is a schematic diagram of assembly of a current transformer of the present invention.

Fig. 11 is a wiring schematic diagram of a current transformer of the present invention.

Fig. 12 is a working principle diagram of a current transformer of the present invention.

Reference signs in the figure:

Housing 1, M3 pressing screw 2, secondary outlet terminal 3, secondary coil 4, primary cable hole 5;

Upper housing 1.1, upper housing screw mounting holes 1.1.1, secondary coil sleeve 1.1.2;

Lower casing 1.2, lower casing screw mounting holes 1.2.1, secondary outlet terminal slot 1.2.2, secondary outlet terminal identification 1.2.3.

detailed description

Referring to Figures 1 to 12, the utility model relates to a current transformer. The shell 1 of the transformer is composed of an upper shell 1.1 and a lower shell 1.2, and the lower shell 1.2 is provided with three secondary Secondary outlet terminals 3 (a, b, c), the upper casing 1.1 and the lower casing 1.2 are respectively provided with two primary cable holes 5 for the primary cables to pass through, and the casing 1 is provided with Two secondary coils 4, and the two secondary coils 4 and the two primary cable holes 5 are respectively arranged correspondingly;

For two secondary coils 4, one of the secondary lead-out wires in one of the secondary coils 4 is connected to the first secondary lead-out terminal 3 (a) of the lower case 1.2, and the other lead-out wire is connected to the lower case 1.2 The third secondary outlet terminal 3 (c), one lead wire of the other secondary coil 4 is connected to the second secondary outlet terminal 3 (b) of the lower casing 1.2, and the other lead wire is connected to the lower casing 1.2 The third secondary outlet terminal 3 (c) - as shown in Figure 11;

When in use, the primary cable is connected in series in the circuit through the primary cable hole 5, and the lead-out line of the secondary coil 4 is connected to the back-end measurement circuit through the secondary terminal 3;

Below in conjunction with Fig. 1～9, above-mentioned embodiment is described in detail:

A current transformer of the utility model includes a housing 1, a secondary coil 4 disposed inside the housing 1, a secondary terminal 3 disposed outside the housing 1, an M3 pressing screw 2, and a primary cable hole 5 and related installation parts;

The housing 1 is composed of an upper housing 1.1 and a lower housing 1.2. The outer bottom of the upper housing 1.1 is provided with a screw mounting hole 1.1.1. The upper housing 1.1 and the lower housing 1.2 are Two primary cable holes 5 for the primary cables to pass through are provided respectively; two vertically arranged secondary coil sleeves 1.1.2 are arranged between the upper casing 1.1 and the lower casing 1.2, and the secondary coil The upper and lower openings of the sleeve 1.1.2 are facing the primary cable hole 5, and the primary cable passing through the primary cable hole 5 is inserted into the secondary coil sleeve 1.1.2; the secondary coil 4 is set in the secondary coil sleeve Barrel 1.1.2 on;

The secondary coil sleeve 1.1.2 is provided with a slot for holding the secondary coil 4, and the slots on the two secondary coil sleeves 1.1.2 are respectively provided with , Two limit openings for placing and positioning the secondary coil 4, the secondary coil 4 is divided into , , where the coil embedded in limit port, coil embedded in Limiting opening; the outer bottom of the lower housing 1.2 is provided with a screw mounting hole 1.2.1, and the outer top of the lower housing 1.2 is provided with three secondary terminal slots 1.2.2, and the three secondary terminal terminals 3 are respectively Embedded in three secondary connection terminal slots 1.2.2, the secondary connection terminals 3 respectively correspond to connection terminal marks a, b, c, the secondary connection terminals 3 are provided with M3 threaded holes, the two M3 pressing screws 2 are respectively screwed on the secondary terminal 3;

The secondary coil 4 is respectively provided with two lead wires S1, S2, the secondary coil The S1 and S2 lead-out wires are respectively connected to the secondary terminals (a, c), and the secondary coil The S1 and S2 lead-out wires are respectively connected to the secondary terminals (b, c);

Wiring principle:

The wiring principle of a current transformer of the utility model is shown in Figure 11, because the three-phase current vector sum is zero in the neutral point ungrounded system, so the third phase current can be calculated only by measuring two phases;

working principle:

The working principle of a current transformer of the utility model is shown in Figure 12. The primary winding of the current transformer is connected in series in the line to be tested. I1 is the line current, that is, the primary current of the current transformer, and I2 is the secondary current of the current transformer. Z2e is the impedance of the secondary circuit equipment and connecting wires. When the primary current flows in from the P1 terminal of the current transformer and exits from the P2 terminal, when the secondary Z2e is connected, based on the principle of electromagnetic induction, the secondary winding of the current transformer has a current I2 flowing from S1, through Z2e to S2, form a closed loop. From this, it can be obtained that the current is I1×N1=I2×N2 in an ideal state, so I1/I2=N1/N2=K, and K is the transformation ratio of the current transformer.

In addition: it should be noted that the above specific implementation is only an optimization solution of this patent, and any changes or improvements made by those skilled in the art based on the above ideas are within the scope of protection of this patent.

Claims (5)

1. A current transformer, the housing (1) of the transformer is composed of an upper housing (1.1) and a lower housing (1.2), and the lower housing (1.2) is provided with three two The secondary outlet terminal (3) is characterized in that two primary cable holes (5) for the primary cables to pass through are respectively arranged on the upper casing (1.1) and the lower casing (1.2), and the casing Two secondary coils (4) are arranged inside the body (1), and the two secondary coils (4) and the two primary cable holes (5) are respectively arranged correspondingly; For two secondary coils (4), one secondary lead-out wire of one of the secondary coils (4) is connected to the first secondary lead-out terminal (3) of the housing (1.2), and the other lead-out wire is connected to The third secondary outlet terminal (3) of the lower casing (1.2), one lead wire of the other secondary coil (4) is connected to the second secondary outlet terminal (3) of the lower casing (1.2), and the other One lead-out line is connected to the third secondary lead-out terminal (3) of the lower casing (1.2). 2. A current transformer according to claim 1, characterized in that: two vertical secondary coil sleeves (1.1.2) are arranged between the upper casing (1.1) and the lower casing (1.2) between, and the upper and lower openings of the secondary coil sleeve (1.1. 2) inside; the secondary coil (4) is set on the secondary coil sleeve (1.1.2). 3. A current transformer according to claim 1, characterized in that: three secondary terminal slots (1.2. 3) Embed in the three secondary terminal slots (1.2.2) respectively. 4. A current transformer as claimed in claim 3, characterized in that: the secondary terminal (3) is provided with M3 threaded holes, and the secondary terminal (3) is respectively screwed with M3 pressure screws (2). 5. A current transformer according to claim 1, characterized in that: the outer bottom of the upper casing (1.1) is provided with screw mounting holes (1.1.1), and the outer bottom of the lower casing (1.2) Provided with screw mounting holes (1.2.1).