SU1711255A1 - High-voltage sealed-contact reed relay - Google Patents

Abstract

The invention relates to electrical engineering, more specifically to electromagnetic relays on reed switches having high voltage insulation between the control and control circuits. The device allows maximum current protection of a high voltage AC installation without the use of a current transformer. The achievement of this effect became possible due to the special design of the relay housing, which allows it to be installed directly on the bus of the installation to be protected, as well as using a special electronic converter in it. 1 hp ff, 3 ill.

Description

at

J

The invention relates to electrical engineering, specifically to an electromagnetic relay with reed switches and high-voltage insulation between them and a source of a control floor (gerkotrony), and can find a source in control systems and protection of high-voltage electrical networks. :

A high-voltage reed switch is known, which contains a cylindrical dielectric case with two cavities on the side of the case, one of which has a longitudinal axis of the reed switch, and the other is a control winding.

A disadvantage of this device is its limited scope due to the impossibility of using power plants with high-current circuits with currents of the order of hundreds of thousands of amperes, as well as into AC circuits due to vibration of the reed switch and the impossibility of including it in standard protection circuits. .

Closest to the present invention is a high-voltage reed switch containing a dielectric body in the form of a glass, a reed switch lowered to the bottom of the body, a round dielectric plate with an annular protrusion in the central part and the source of the control MDS in the form of a coil mounted on the dielectric body. The reed switch in the device is placed with its longitudinal axis along the axis of the housing, and the dielectric plate is screwed onto the outer surface of the dielectric housing in its upper part, with the annular cavity of the plate facing the external leads of the reed switch, and the control winding together with the lower part of the dielectric housing with the reed switch is enveloped by a ferromagnetic shield .

This relay also has these disadvantages.

The aim of the invention is to expand the field of use by using a

relay in high current AC circuits.

A high voltage reed switch containing a dielectric body, a dielectric plate with a central hole and an annular protrusion around the central hole, a reed switch and an MDS source, the dielectric body is made in the form of a glass with an open cavity to accommodate the reed switch, the cavity on the other side of the dielectric body is bounded by a blind end face the wall, the specified dielectric body is threaded on the outer surface and passed into the hole of the dielectric plate, and the reed switch is placed in the cavity of the dielectric body at its bottom, equipped with an electronic converter, the end of the dielectric body ending with a blank end wall, is tapered with a protrusion on the outside, the thread is made on the specified protrusion, a conductor bus with a central hole is used as the source of MDS, a dielectric plate equipped with divisions and installed on the protrusion of the dielectric body so that the annular protrusion faces the protrusion of the dielectric body, at the end of the protrusion is placed on the nut, the specified busbar is located on the protrusion of the dielectric body between the nut and the central protrusion of the dielectric plate, the reed switch is placed in the cavity of the dielectric body so that its longitudinal axis is perpendicular to the longitudinal axis of the dielectric body, and is connected to the input of the electronic converter.

The electronic converter can be made in the form of a transistor, a capacitor and two resistors, the capacitance of the capacitor is chosen from

 - arcsln

1ЈP

FMKhsin

 arcsln

F opt

IM K h sin a

7Tft) RM

where Fcp, Forn is, respectively, the magnetomotive force of actuation and release of the reed switch,

1m is the amplitude value of the bus current, leading to the actuation of the reed switch;

Kh - distance coefficient of the reed switch from the tire;

a is the angle between the longitudinal axis of the reed switch and the tire;

ft) is the angular frequency of the bus current;

Rn is the load resistance of the relay, and the resistance of the base resistor of the condition

arcsln

FC0

R6SIM K h sin a

+ arcsln

F opt

M K h sin (Z

-1pcpbus

where Kp is the voltage ripple factor allowed for the relay load.

The high-voltage dielectric case of the relay has a special design that allows it to be installed on the busbar and to use the latter in

0 as a source of control MDS, in addition, the relay is equipped with an electronic converter, which excludes the penetration of current oscillations caused by the vibration of a reed switch in an alternating field into the load of the relay.

5 In FIG. 1 shows a longitudinal section of the device with an electronic converter circuit; in fig. 2 is a circuit for connecting the load to the relay; in fig. 3 - oscillograms of bus currents, at the input and output

0 electronic converter.

The high-voltage reed switch contains a dielectric case 1, the bottom of which is made cone-shaped with a protrusion from the outside, a dielectric plate 2 with a central hole and an annular protrusion reed switch 3 located at the bottom of the case 1 so that its longitudinal axis is perpendicular to the body axis, and connected to the input of the electronic converter 4.

A current-carrying busbar 5 of a high-voltage installation / provided with a hole for the protrusion of the dielectric body 1 was selected as the source of the control MDS,

5 located along its longitudinal axis. The electronic converter 4 comprises a transistor 6, a capacitor 7, a bias resistor 8 of the base circuit, and a base resistor 9. Relay terminals connected to the output

0 of the electronic converter 4, are made with a high-voltage cable (for example, of the type RMPVN) and in series with the load (Fig. 2) are connected to a low-voltage power source of a constant tick.

5 The relay works as follows.

When a short-circuit mode in the protected installation occurs, the current in bus 5 increases significantly, and the MDS created by it, changing sinusoidally to the MU law, leads to alternate triggering and releasing of the reed switch 3 (FIG. 3), and due to the high speed of the reed switch, it has time to react for each half-wave of the current and its switching-on frequency is twice the frequency of the current in the bus 5. When the reed switch 3 is first closed, a positive potential is applied to the base of transistor 6, it opens and a current begins to flow in the load. Simultaneously with the opening of the transistor 6 when closing

, reed switch contacts 3 charge the capacitor. Opening the reed switch contacts (when the MDS current in bus 5 decreases to the MDS value of the reed switch) does not instantly close the transistor b, because capacitor 7, discharging through resistor 9, maintains a positive potential at the base until the next closure of the reed switch 3, during which a capacitor charge occurs, etc. Thus, current oscillations caused by the vibration of the reed switch are not transmitted to the load of the relay, for example, the winding of an intermediate relay connected to the control circuit of the circuit breaker of the installation can be used.

The sensitivity of the relay is proportional to the sine of the angle a between the longitudinal axes of the reed switch and the tire, and inversely proportional to the distance h between these axes. Taking into account that for a reed switch operating in the field of a tire, the FCS of the FCp and the release of Roth are adequate to the values of the current of operation and release in the bus, we can write

Fcp.

rep

I OTP -

K h sin a

F opt

K h sin a

(1) W

where Icp, lorn is the bus current, which leads respectively to triggering and releasing the relay reed switch;

Kh is a coefficient depending on the distance between the longitudinal axes of the reed switch and the tire .; Thus, by turning the dielectric case of the relay around its axis, it can be tuned to different actuation currents, and the divisions applied on the periphery of the dielectric plate 2 ensure the accuracy of the installation of the relay tuned to the specified current on the bus. 4 is carried out as follows.

The reed switch 3. is excited by a variable sinusoidal MDS, when DC is switched on in a circuit, it generates square-wave pulses with a duration Ti and a pause tn (Fig. 3). The capacitor 7 must have time to charge during the time when the reed switch contacts are in a closed state, i.e. the total charge time must satisfy the condition tfRHC U

where is its capacity 7CHG (3)

WITH

When capacitance is discharged during a pause, it is necessary that the attenuation of the free component of the transient voltage on the base resistance of transistor 6 does not exceed the specified ripple factor on the load Kp (which, when used as a load, the intermediate relay can be characterized by its return ratio)

CP

and.

U

where U1 is the load voltage after a time ;.

Y is the nominal load voltage. This requirement can be rewritten as

(-fsg)

where ReC is the constant of the discharge time of the capacitor C to the base resistor Re, whence the resistance of the base resistor is determined

-In knlt

2Q From the oscillogram (Fig. 3) it can be seen that the duration of the pulses generated by the reed switch is determined by the expression

ft)

(five)

in which the phases of the current wti and wt2 are respectively equal

ysc arcsln

Icp

(6)

40

l

and t2 arcsln + 2 (Ј - arcsln i-p-)

i tna

, tf-arcsin -, (7)

where Icp, lorn is the control current value, which leads respectively to the actuation and release of the reed switch;

1m - the amplitude value of the control current.

Taking into account (1) and (2) have.

50

arcsln- arcsin, avg

m K h sin a F Opt

1m K h sin a

(AT 9)

55

Substituting (B) and (9) in (5), the final expression is obtained to determine the duration of the pulses generated by the reed switch.

3t - arcsln

cp

tn

iMKhslna

- arcsln

off

1m K h sin a

(40)

The duration of the pause tn is related to the pulse duration (Fig. 3) as follows:

tn-t-tii,

where T is the period of impulses generated by the reed switch, which is always l for a sinusoidal control signal, or taking into account (10)

arcsln

1m K h sin a

4- arcsln

F opt

(O

Thus, expressions (3) and (4), taking into account expressions (10) and (11), take the form

Fcp 1m K h sin С

arcsln

 off

1m to h

(Yann

arcsln

Rdr

R6 s

lMKhslna

4- arcsln

Foh

lMKhslnCt

-.{13)

-tnKnCDC

Suppose a KEM-2 type reed switch is used in the relay (FCp “13 A, R0TP 12 A), the winding of the intermediate relay type RPU-0-UHLCCH-110V (RH 7300 Ohm, Kp-0.9) is used as its load. the angle between the longitudinal axes of the reed switch and the busbar is 90 °, the isolation level, the relay from the bus is 10 kV (with the distance between the reed switch and the bus providing this level, Kh is 0.1), and the current KOpotKoro equal to 300 A. Then, according to (12) and (13) receive

- arcsln

13

U5GSOO-O.

-arcslnЛ.

I ZOO 0.1 sin 96 °

W, m -3.14-7300

-3.5-10 7Ф "OL5" (F:

HS 1.t 13-

Re have zoo-o .. slnSO0

-arcsJo

12

V5 300-6.1 1in 90

. -In0.9--3t43. -51660 ohms .6 "ohms.

The proposed device is practically implemented and implemented in systems of maximum current protection of electrical installations of 6-10 kV. Thus, the proposed device has a wider application than the known.

Claims (2)

Claim 1. High-voltage reed switch comprising a dielectric body, a dielectric plate with a central hole and an annular ledge around The central branch, the reed switch and the source of MDS, the dielectric body is made in the form of a glass with an open cavity, designed to accommodate the reed switch, indicated 5 on the cavity on the other side of the dielectric body limited by a blank end wall, the specified dielectric body is threaded on the outer surface and passed into the hole dielectric plate, and the reed switch is placed in the cavity of the dielectric body at its bottom, characterized in that. that, in order to expand the field of application by using relays in high-current 15 alternating current circuits, it is equipped with an electronic converter, the end of the dielectric body, ending with a blank end wall, is tapered with a protrusion on the outside, 20, the thread is made on said protrusion, a current-carrying bus with a central hole is used as the source of the MDS, the dielectric plate is provided with Fissions and is installed at the height of the dielectric body so that the annular protrusion faces the protrusion of the dielectric body; The specified busbar is located on the shoulder 30 of the dielectric body between the nut and the central protrusion of the dielectric plate, said reed switch is placed in the cavity of the dielectric body so that its longitudinal axis is perpendicular to the frontal axis of the dielectric body and is connected to the input of the electronic converter. 2. A relay according to claim 1, characterized in that the electronic converter is designed as a transistor, a capacitor and two resistors, a collector of the transistor and a common connection point of the emitter of the transistor, the negative terminal of the capacitor and one of the terminals of the bias resistor The 45 base circuits form the relay output, and the collector of the transistor and the common connection point of the positive terminal of the capacitor and one of the terminals of the base resistor are the input of the relay, and the capacitance of the capacitor is selected from the condition LCЈiFMKhslna - arcsfn Rott lMKhslnCC ytti) R where Fcp, Forn are, respectively, the magnetomotive force of actuation and release of said reed switch; 1M, is the amplitude value of the current in the bus leading to the actuation of the reed switch; Kh - distance coefficient of the reed switch from the tire; a is the angle between the longitudinal axis of the reed switch and the tire; O) - the angular frequency of the current in the bus; RH is the load resistance of the relay. Ohno and the resistance of the mentioned base resistor is conditional. . arcsln F " 1M K h sin and f arcsln RTP lMKh3lnЈC  R6 -InKnWC where Kl is the voltage ripple coefficient allowed for the relay load. } 6-ShkV W, 2 Rig.Z