CN2265615Y - Overcurrent relay - Google Patents

Abstract

The utility model discloses an over current relay. An I-V sensor can obtain a current signal from the electric network; the current signal can control an electronic switch after the current signal is processed by an over current circuit, a short-circuited circuit, a phase failure processing circuit; a V-V sensor can obtain a voltage varying signal from the electric network; the voltage varying signal can control the electronic switch and can drive the load after the voltage varying signal is processed by an over voltage processing circuit and an under voltage processing circuit; each phase of the I-V sensor adopts an O-shaped iron core; a primary side coil adopts the core penetrating type (namely one coil); a secondary side coil adopts the rolling type (winding on a coil rack); a three-phase coil needs three coils which have the same structure and the iron core. The utility model has the advantages of high sensitivity, large current range, small size, and light weight. The utility model can work in two states of the AC state and the DC state.

Description

Overcurrent relay

The utility model relates to relay, relates in particular to overcurrent relay.

In modern electric-control system, use overcurrent relay widely, in order to electromechanical equipments such as protection motor.In the electronic type overcurrent relay, its overcurrent signal obtains corresponding voltage by instrument transformer usually, obtains through over commutation, filtering again.This processing method has two disadvantages: the general overcurrent relay volume of the first is less, and the current transformer core cross section is also less, makes core sataration easily, causes the distortion of secondary induced potential, causes distorted signals.And because of the about 0.7V of the turning-on voltage of diode, if full-wave rectification, signal amplitude should 〉=1.4V, when primary circuit electric current hour, be difficult to obtain distortionless signal.Its two, according to the characteristics of overcurrent relay, the signal in the time of need obtaining general overcurrent and short circuit, the signal of obtaining when it has been generally acknowledged that the 8-10 of rated current can be used as short-circuit signal.Overcurrent relay also often needs a working range, as 5A-50A, differs 10 times if consider the maximum and the minimum value of primary current, so as overcurrent signal, its maximum and minimum value will differ 100 times, get 10V as signal maximum, and then minimum value has only 0.1V.The discreteness of diode turning-on voltage will make diode conducting need be biased voltage like this, owing to must be introduced error.Owing to the possible deviation of bias voltage, reduced the reliability of device, the as seen sensitivity of traditional processing method, reliability is all relatively poor.

In the electronic type overcurrent relay, often requiring has electrical network overvoltage, under-voltage indication, and the extraction of over-and under-voltage signal is often in the mode of transformer step-down, and this transformer and need power transformer shared for overcurrent relay itself.Volume unsaturated for transformer core when the overvoltage, iron core wants big, increase the volume of device, and because a shared transformer, because under-voltage signal false overvoltage also can appear, in the influence of load variations own.

The purpose of this utility model provides a kind of overcurrent relay

The explanation that adds below in conjunction with accompanying drawing.

Fig. 1 is the overcurrent relay functional-block diagram.

Fig. 2 is single-phase I-V sensor electrical schematic diagram.

Fig. 3 is a V-V sensor electrical schematic diagram.

As shown in Figure 1, I-V sensor 2 obtains current signal, warp from electrical network 1 among the figure After overcurrent, short circuit, disconnected phase treatment circuit 3 are processed, control electronic switch 6; The V-V sensing Device 4 is processed through overvoltage, under-voltage treatment circuit 5 from the signal of electrical network acquisition voltage change After, control electronic switch 6 drives load 7 by electronic switch.

The I-V sensor is two kinds of single-phase I-V sensor and three-phase I-V sensors, Whenever, adopt mutually a square shape iron core. First siding ring adopts core-theaded type (i.e. a circle), secondary Lateral coil adopts takeup type (on bobbin), if three-phase then needs three to tie equally mutually The coil of structure and iron core. The secondary side signal detects respectively its peak value.

As shown in Figure 2, B is the square shape current transformer among the figure, L ₁Be primary winding (1 circle); L ₂Be secondary coil, resistor R ₁In order to restriction secondary singal amplitude.AC signal V _iFrom operational amplifier IC ₁Positive input terminal input, work as V _iDuring positive half cycle, the negative input end level is low, and amplifier output high level, this high level are through diode V ₁Make capacitor C ₁Charging.Because triode V ₂The effect of following, in resistor R ₄On obtain output signal V _O,

Through resistor R ₃, R ₂Feed back to operational amplifier IC after the dividing potential drop ₁Negative input end.Work as V _iDuring negative half period, because of negative input end level height, amplifier output low level.Because V ₁Existence, the low level of this moment output is to C ₁Do not exert an influence C ₁On still keep former high level.When having only the negative input end level to be lower than positive input terminal later on, operational amplifier IC ₁High level output is just arranged, make C ₁Charging, when negative input end is higher than positive input terminal, C ₁Keep original level, the result: (V in the formula _IBe V _iPeak value).

Work as R ₃=0 o'clock, V _O=V _I, promptly output level equals the peak value of input signal

R ₂=R ₃The time, V _O=2V _I, promptly input signal has been exaggerated one times

Three-phase I-V transducer adopts three single-phase I-V transducers.

As shown in Figure 3, among the figure, line voltage is directly by transducer input A, B input, through resistor R ₅Buck diode V ₃Rectification enters photoelectrical coupler IC ₂, IC ₂Output through resistor R ₆Ground connection.R ₆Output voltage signal is through diode V ₄Rectification, capacitor C ₂Filtering obtains output signal V _O, voltage V _OAmplitude be proportional to the peak value of line voltage.The V-V transducer utilizes photoelectrical coupler IC ₂Extract signal, and play electric buffer action.

Advantage of the present utility model: highly sensitive owing to adopted the I-V transducer, inferior coil is a circle (core-theaded type) electric current when being 0.5A, is output as 50mV.Primary side all adopts core-theaded type so can be applicable to the occasion that needs on-line measurement.The ratio of the maximum of the big primary side current of current range and minimum value is 10.Owing to adopted the V-V transducer, compare with the transformer step-down, reduced the scale of construction and weight greatly, can be operated in the alternating current-direct current two states, the A end is for just during direct current, and the B end is for bearing.

Claims (2)

1. an overcurrent relay is characterized in that I-V transducer (2) obtains current signal from electrical network (1), after overcurrent, short circuit phase failure treatment circuit (3) are handled, and control electronic switch (6); V-V transducer (4) is from the signal of electrical network (1) acquisition change in voltage, and through overvoltage, after under-voltage treatment circuit (5) was handled, control electronic switch (6) drove load (7) by electronic switch; B is the square shape current transformer in the single-phase I-V transducer, L ₁Be primary winding, L ₂Be secondary coil, resistor R ₁Restriction secondary singal amplitude, AC signal V _iFrom operational amplifier IC ₁Positive input terminal input through diode V ₁Make capacitor C ₁Charging is because of triode V ₂The effect of following, in resistor R ₄On obtain output signal V _O, V _OThrough resistor R ₃, R ₂Feed back to operational amplifier IC after the dividing potential drop ₁Negative input end; Three-phase I-V transducer adopts three single-phase I-V transducers.

2. a kind of overcurrent relay according to claim 1 is characterized in that the V-V transducer, and input A, B and electrical network join, and input voltage is through resistor R ₅Step-down, diode V ₃Rectification enters photoelectrical coupler IC ₂, IC ₂Output through resistor R ₆Ground connection, R ₆Last output voltage signal is through diode V ₄Rectification, capacitor C ₂Filtering obtains output signal V _O

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