DE2360564A1 - Switch contact protective device - has current gate parallel to switch contact controlled by RC element - Google Patents

Abstract

The protective device for switching contacts against wear and abrasion uses a current gate parallel to the switching contact, in which the auxiliary contact is located against the rest side of a change-over switch and the load contact against the working side of the switch. The igniting current for the current gate is generated by a parallel connection of a RC-element and an ohmic resistor. This parallel connection is coupled at one side to the main voltage and at the other side to the rest contact which short circuits the gate of the protective circuit. The igniting current is provided by a capacitor as d.c., the capacitor being connected in parallel to the gate-anode path of current gate via a series resistor. The capacitor is charged from the mains voltage via another resistor.

Description

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The invention relates to devices for protecting electrical con cycles against wear; beioi ic-halteri. "-"., ..

Teacher-like / devices should have as little need as possible and less; V / poor development carried out ^ Vierden.-This is-especially important for control devices with a larger number of i-contacts. - ■ -..- .. _: '- _: ". [ _: " _.-. ""'.--""".-. ■

_) s are: current gates in 3 series and parallel ζμία 3switching contact ^: - "- known. Current gates connected in series must be designed for the nominal current and must develop correspondingly much heat. Current gates connected in parallel to the contact carry the characteristic current only as an impulse current during the holding process and can be designed correspondingly smaller. In one known solution: the ignition current is generated by a V / resistor connected to the voltage (Fig.'i) Changeover switch short-circuited, which opens when the load contact closes. The resistor must be designed in such a way that it can generate the ignition current at approx this results in increases a resistance of 1k, he ^r d at 22 V ο about 5oW on.

The purpose of the invention is to create a solution with less space requirements, less poor development and different control methods. : .'..-

Polgende i-methods for controlling the power gate are provided:

1. ii & s control signal for the power gate is “generated by an auxiliary contact. "_" ■ -, - ■ ";

2. The control signal for the electricity gate is from the driver signal ■ derived for contact actuation.

3. The control signal for the power gate is based on the rated voltage of the opening spark derived V.

509824 / Ö099 BAÖORIGINAL

x'ig.2 shows a solution with a known switching con. clock, where the ignition current for the triac from the parallel circuit an RC element with an ohmic vVid-erstand is generated. The liC element supplies the ignition current in the. Near the voltage zero crossing and the parallel resistance close to the voltage maximum. Fig.3 shows a solution in which the Ignition current generated as direct current from a capacitor C2 is, here it is sufficient if the series resistor λ 2 is the ignition current at the nominal voltage.

.the auxiliary contact is isolated from the load contact in terms of potential, a circuit according to Pig. 4 is possible. It uses a diode bridge 'with a thyristor in the DC voltage branch as Electricity gate used. As the ignition current is essential for thyristors can be smaller than with triacs, the heat development is reduced corresponding.

Circuits according to Pig 5 and ^ 6 are possible with an auxiliary contact ₇ that is actuated in the same direction as the load contact. It is essential that the ignition current only flows in the short times around difi-the auxiliary contact closes before the load contact or after The ignition current must be generated at the lowest possible operating voltage of the opening spark (anode plus cathode drop). This also applies to circuit after

The power gates for multiple load contacts are v / grounded by just one Control contact in circuit according to Fig. 7 controlled. Have along the resistors R5, Ti6, -in ^ the task of the ignition current to the Gates G1, G2, G3 evenly distribute. In order not to have to apply the ignition current as a continuous current, a circuit according to Fig. 8 is used. The ignition current is generated as in Fig. 5. Included

> Fi— must, however, be avoided that when closing the x.ontakie the ignition circuit is not 'short-circuited' by the triac * 1, before the other triacs have ignited. For this purpose, the capacitor C3 is charged and Triac 1 can only be ignited when the Zener voltage is reached by the Zener diode ZL2.

According to Fig. 9, the ignition currents are supplied from a transformer,

509824/0099

BATH ORIGINAL

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the voltage from an auxiliary contact switching in the same direction is placed. Will the ignition currents slow down separately removed, the load contacts can be placed under shelves Potentials lie. This is important for triangular connections in three-phase networks.

If the contacts are actuated electromagnetically, the auxiliary contacts can be dispensed with and the control signal for the current gates is derived from the control signal for the actuating magnet. which first goes through the capacitor C3 «and later through the base of the transistor Tr2. This means that the ignition current is switched on with a delay. If the relay is switched off, the base current of the transistor Tr2 flows through the V resistor R11 and the capacitor C4 until it is charged accordingly. This means that the ignition current is switched off with a delay. The drop-out delay is required to compensate for the drop-out time of the relay, while the pull-in delay serves to reduce the current flow time in the triac. I ^r 'ig.13 shows such a circuit together with a current gate consisting of a diode bridge and a thyristor.

I? - shows a .circuit at "which is the voltage of the spark on the switching contact to trigger the ignition signal for the electricity gate serves. When the contact opens, the contact voltage jumps to a value of at least the node-plus cathode drop voltage This voltage is initially at the divider R2o, R21. This voltage U-1 is higher than the switching voltage of the Scbiwellwerts'chalters SS!. This ignites the thyristor; and takes over the load current, which is a voltage drop across the resistor, B16 generated. From this the capacitor C6 is connected to the Diode D6 charged. This means that transistor Tr3 receives base current and short-circuits the resistor R21 so that the threshold can vrert he does not switch the thyristor in the following half-wave. In this half-square the capacitor G5 is at its apex the operating voltage charged (U3) .; Lie voltage on 05

now supplies the base current for Tr3 via the divider d17, Ri9 and via.R18. This ensures that Tr3 also after the Discharge from C.6 on remains controlled. This has the effect that

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BATH

voltage peaks in the chain do not pass the thyristor via the threshold switch 331 can ignite. Such large voltage peaks occur on that the components of the circuit are endangered, so arises in ri.2o a correspondingly large current, which has a voltage U2 generated to which the threshold switch 332 responds and the Thyristor ignites, which briefly slept the bridge. Closes the switching contact again, then C5 is discharged via R17, 1-19 and-.to some time the transistor Tr3 blocked. This means that the circuit is ready again when the switch contact opens address the spark voltage.

Pig.13 shows a simplification of the circuit of Pig.12. Ler at voltage jump occurring in the bridge when the contact is opened is divided down with the divider R2o to R23 + R24. The transistor Tr4 together with R23 / 24 forms a threshold switch, ' As soon as Tr3 carries current, the ratio of U2 to U4 is increased that the threshold switch only responds to dangerously high mains voltage peaks, the 2nd threshold switch can omitted.

In order to be able to switch an isolating contact load-free, a switch contact is connected in series in Pig.14, to which a 'current gate according to the circuits described ^; is connected in parallel. .

For thermal reasons, there is often no semiconductor switch for timing relays be used. This problem is solved in that the mechanical output contact is a current gate in the described Way is connected in parallel. The output relay thus achieves its mechanical service life regardless of the type of load of the system. - -

5098 24/0089.

BATH

Claims (1)

Council waiver ■ "-.-". Λ J Stromtor "parallel to a switching contact with the resting side of a changeover switch as liilf skontakt (T) and the working side (2) as load contact characterized in that -the ignition current for the Stromtor from the parallel connection of an RC- * G1 ie des (3) with an ohmic resistor (4) is generated and the parallel circuit is connected to the Eetζvoltage on one side and to the normally closed contact on the other side, which short-circuits the gate of the current gate C5) '. 2. Current gate parallel to a switching contact, characterized in that the ignition current is a direct current from a capacitor (6) which is parallel to the gate-anode 1 path of a current gate via a series resistor (7) and the capacitor via a 2 · VorwiderstancbTan the line voltage is charged. 3.:Stomtor parallel to a switching contact characterized by, that the stomtor a Diodenbrücka, (8,9,1 ο, 11) with a Thyristor (12) in Gleichspännungszweigru ^ d a ^ with the switching contact operated in opposite directions auxiliary skontakt (13) «fc * the gate of the thyristor (12) short-circuits. . ... 4. Stromtor parallel to a switching contact ^: characterized in that the auxiliary contact is actuated in the same direction with the switching contact and and the circuit for generating the ignition current including auxiliary contact with ein.r side zv; ical load and ■ "switching contact (14) and with the on the other side at the gate of the power gate, (15). ■,. ■■■ 5. Claim according to 4, characterized in that the ignition current · ■ is generated by an ohmic resistor (16). ■ ": - 6. Claim according to 4 and 5, characterized in that the required ignition current is already at the voltage corresponding to the; ... Sum of the anode and cathode drop voltage of the contact will. ■ 509824/0099 BADQRiGiNAt 7. Claim according to 4 to 6, characterized in that a diode bridge with a thyristor in the DC branch is used as the current gate will. ·. - 8. Power gates (18.19 »2o) - parallel to" multiple "switching contacts (21 ·, 22,23) characterized in that only one common auxiliary contact (24) ″ is used. 9. Claim according to 8, characterized in that the auxiliary contact is operated in the same direction as the i_astkontakten and unilaterally between the load and load contact (28) of a phase and the ignition current is delayed for this phase. 10. Claim according to 8 and 9, characterized in that the current gates on one side at the same potential "and the ignition current with resistors (25,26,27) between the ignition current source (17) and is evenly distributed to the individual gates. 11. Claim according to B, characterized in that der.Zündstrom comes from a transformer (3o) and the power gates are optionally supplied with ignition current from separate windings, potential-free, 12. Stromtor parallel to a switching contact, characterized in that the control signal (31) for the Lontakt actuating magnet is used to generate the ignition signal (32). 13. Claim according to 12, characterized in that the ignition signal for the Stomtor opposite the control "of the magnet is generated with dropout delay and / or delayed (33). H? Claim according to 12 and 13, characterized in that as Stromtor optionally a triac or a diode bridge with a x'hyristor in the direct current branch (34) is used. 15. Stromtor marked parallel to a Schaltko'fttakt in that the operating voltage of the opening function is used to generate of the ignition signal is used. 16. Claim according to 15, characterized in that a contact voltage ^ the anode drop plus cathode drop voltage (ionization voltage plus workload) of the contact material the electricity gate ignites. _ " 50 9 824/0059 BAD ORiGfNAL 1-7. Addressed according to 15 and 16 characterized in that, that one ^ iodenbrücke (35) with a thyristor (36) in the DC voltage supply / proper al3 3-tromtor is used and that from the i-lus.seite the ■ Gap an i capacitor (.37) and from the capacitor a resistor (3B'j (RC-u-lied) goes to the ^ inusseite of the bridge and the tension on resistance or on part of the /.resistance the ignition signal represents. · '. 18. x, & nsOruch according to 17 characterized in that the ijaststrom dui "ch the" thyristor, a -ignal generated, y ^ at least ^in: suppressing a possible ignition signal next-Lalbwelle. 19. Claim according to J4-to 18 characterized .that that the Ignition signal is suppressed by a transistor (39) short-circuits part of the Y / resistance ^ a of the RCx element and ■ · its base goes through a resistor (4o) to a capacitor (41) to the bridge minus and between the cathode of the thyristor and bridge minus is a resistor (42) which is parallel to the capacitor (41) via a diode (43). 20. Claim, characterized according to 1-5 to 19. Characterized in that at a voltage on the thyristor (36) greater than the maximum burning voltage of the spark via a voltage divider (44, 45) the base of the transistor (39) is activated and thus a possible ignition signal is suppressed .. 21.Anspruch according to 15 to 2o, characterized in that ^; the ignition signal via a threshold switch (46). arrives at the gate of the thyristor. ': 22. Claim according to 15 to 21, characterized in that, as a threshold switch, either a ünijunctiontransistor, a Zener diode, an I'ransistpr _: (48) with a voltage divider (49.5o) 'or HlZJS. Minimum ignition voltage and current of the thyristor together with a resistor is used. , · · 23. -nspruch according to 15 to 22, characterized in that the semiconductor against overvoltage by triggering the thyristor ^; * , to be protected. "". · -. ³ ORIGINAL BATHROOM 24 according to claim 15 to 23 characterized in that the firing of the thyristor with overvoltage by threshold (47) is carried out according to claim 22nd 25. Claim according to 15 to 24, characterized in that the thyristor is ^{ignited only with a threshold switch (49 ^ 5o, 4:} 8) and the voltage (U2) required for ignition is applied to the "resistors" (49 »5o, 51) of the The RC element is then increased by connecting a V / resistor (52) in parallel to the resistances of the voltage divider (49 »50). 26. Claim according to Ibis 25 characterized in that to the Parallel connection of Schaltkonfcäkt (53) and Stromtor (54) Isolating contact (55) is connected in series, which opens after the switch contact and / or closes before the switch contact. 27. Electronic timing relay marked with contact output in that the contact is connected in parallel with a current gate according to claim Ibis. 509824/0099 Lee on the back