RU2344539C2 - Starter for delta connected electric motors (versions) - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: electric motor starter is two-phase one. One power source phase is supplied to the motor by transit. The starter ensures electric motor protection against open-phase operation including operation with automated control system.

EFFECT: simplifying, improving weight and dimensions characteristics, reducing cost and increasing reliability.

4 cl, 7 dwg

Description

The invention relates to electrical engineering. Known magnetic starters, consisting of three contacts and a mechanical electromagnetic system, for example A. with. 775788. Their disadvantages: relative complexity and material consumption of the structure, low reliability.

The essence of the invention is that for switching a three-phase electric motor connected by a triangle (and most of these motors are now /), it is enough to turn two phases on and off, and the third phase can be connected to the motor permanently (hereinafter referred to as the “transit” phase). That is, the proposed starter is two-phase. It consists of one two-pin / cm. figure 1 / or two single-contact contactors / Fig.1 sub-option depicted by the dotted line /.

The constant presence of one phase on the engine does not harm him. And in a damp room, this can even be useful - isolation during damping will be dried by microcurrent leakage.

You should not be afraid that the presence of a phase on the engine will adversely affect the safety of personnel. Most accidents occur due to the so-called human factor - self-confidence, forgetfulness, etc. Hoping that the engine turned off is de-energized, an electrician can begin to work with it without checking it with an indicator, and may come under voltage from a “stuck” contact or due to another malfunction. Understanding that the engine is constantly energized will discipline staff and it will not begin to work on the engine until it is convinced that it is completely de-energized.

The first version of the starter, consisting of two contactors / are connected synchronously-in parallel or in series / is connected according to the "classical" circuit - to its contacts and with the block contact, bypassing the start-up button / 1 /. The second variant of the starter differs from the first in that it partially / in two phases / protects the motor from out-of-phase operation / Fig.2/.

It consists of one two-contact contactor, the winding of which is connected to the transit phase and to another phase after its own contact. That is, it controls the secondary / after its contact / voltage in the transit phase and in another phase. However, when a contact burns up, the voltage after it does not disappear at all, but remains equal to about half of the interphase / due to overflow through the motor windings and their self-induction /. This may be enough to keep the contactor in the closed position. To avoid this, a symmetric diode thyristor is connected in series with the contactor winding, and the Stop button is also connected in series with the coil to turn off the starter.

The self-opening voltage of the symmetric diode thyristor / hereinafter referred to as the "sidistor" / is selected by a large half of the amplitude working, i.e. for a 220/380 V network, approximately 350-400 V. The holding current of the Sidistor must be less than the operating current of the contactor winding. In this case, the sidistor will miss most of the operating voltage / 60-80% /, but it will not miss half the voltage at all.

For the possibility of starting such a starter parallel to the mentioned contactor contact, a closing Start button is included. The button passes the inrush current of the motor, but for only 0.01 sec / then we will call this button the "direct" button /. The button opens / spark-hazardous mode / already being shunted by the power contact. Therefore, it can commute a current that is much larger than that for which it is designed based on long-term operation.

Or, the starter may have an additional starter winding connected by the start button to its contacts / similar to the “magnetic starter” similar to my invention mentioned below /.

The third option is similar to the second, but it does not control the secondary voltage in the transit phase and another switched phase, but in both switched phases, which is more relevant since Contacts have the ability to burn. However, for the possibility of starting such a starter, a two-pin direct Start button or a starting winding is required.

The fourth variant of the starter is a two-phase analogue of my invention "Magnetic starter" application No. 2005113014 / 09-015008 / patent number is not yet known /. It consists of two single-contact contactors, the winding of one contactor is connected through a sidistor to the transition phase and to the second phase after the power contact, and this contact commutes the third phase. The winding of the second contactor is connected to the transition phase and to the third phase through a sidistor and a stop button connected in series with it, and the second phase commutes this contact. And also the starter has a start button, which shunts the power contact in the third phase, or one of the contactors has an additional start winding.

For use in conjunction with an automated control system / ACS /, two sub-options of the fourth option are possible. They are shown in FIGS. 5, 6. The embodiment in (FIG. 5 is simpler, but in automatic mode / the PC switch in position 2 / does not control the secondary voltage in phase "C" / in the wire "c" /, / sub-option 4a /.

The sub-variant in Fig. 6 controls all secondary voltage, but additionally contains a time relay with self-resetting of РВ / When the relay is turned on, it closes the control contact for 1-2 sec /, / sub-variant 4b /.

It should be noted that in the sub-options in Figs. 5 and 6, the starting current does not pass through the Start button, because two series-connected sidistora C1 and C2 will not miss the amplitude voltage. But it should be noted that the current consumed by the contactor K1 must be at least twice as large as the holding current of the sidistors C1 and C2, because at startup, the latter are connected in parallel.

The fifth option is a two-phase analogue of my invention "Patent", patent No. 2290744. It consists of two single-contact contactors with current windings through which the operating current of the motor passes. Moreover, the mutually contact of one of them is connected sequentially to the winding of the other. And in the transition phase circuit there is a current relay / through the winding of which the operating current of the motor flows /, the opening contact of which shunts one of the windings. And also the starter has a start stop button that shunts one of the contacts, has a stop stop button, shunts one of the windings, or has a stop button in any phase / hereinafter "current stop button /. See Fig. 7.

Such a starter controls not only the secondary voltage, but also the current flowing through the motor in all three phases.

Such a starter, as well as its three-phase prototype, has a property that can be useful to use: with the appropriate settings / bending the tabs of the springs / it can turn itself off when switching to idle mode.

Figure 1 shows the first variant of the starter, figure 2, 3, 4, 5, 6, 7 - respectively, options 2, 3, 4, options 4A and 4b, option 5. Designations: A, B, C - phase / power supply /, a, b, c, - wires, П - two-contact contactor, K1 and K2 - single-contact contactors, KP, KPa, KPb - Start buttons. KS - Stop button, KST - Stop current button, C, C1, C2, C3 - sidistor, PC - switch, ACS - contact of the automatic controller, RV - self-resetting time relay, TP - current relay, L1 and L2 - contactor current windings .

The starter in figure 1 works like this: when you press the KP button, voltage is applied to the two-contact contactor P or / sub-option / to two two-contact contactors K1, K2, connected in parallel and working as one. The power contacts in phases B and C are closed, and the button is shunted by the block contact P. To stop, the circuit is restored to its original state by pressing the KS button.

The starters in figure 2 and 3 work like this: when you press the KP button, voltage is applied to the winding of the two-contact contactor P, the power contacts close and the starter locks itself. When the COP button is pressed, the winding is de-energized, the contacts open.

The starters in Figures 4, 5, 6 in manual mode / the PC switch in position 1 / work as follows: when the KP button is pressed, voltage is applied to contactor K1, which closes the power contact in phase B and voltage is applied to contactor K2. After releasing the KP button, the voltage at K1 is supplied through the sidistor C2. The starter is on.

To stop, the KS button is pressed, the contactor K1 is turned off, and the contactor K2 is de-energized. The starter is off.

In automatic mode, the PC switch in position 2 / the starter in Fig. 5 works as follows: when the ACS contact is closed, voltage is applied: through the sidistor C1 to contactor K1, the power contact closes in phase B, voltage is applied to contactor K2. After releasing the KP button, voltage to K1 is supplied through C2. The starter is on. When the ACS contact opens, the starter is disconnected.

If the voltage in the wires "a" or "b" disappears, the contactor K2 is de-energized and the starter is disconnected.

The starter in Fig.6 operates in automatic mode as follows: when the ACS contact is closed, the voltage through C1 is supplied to K1 and to the relay. time with self-return of RV. After 1-2 seconds, the RV is turned off, and the voltage at K1 is supplied through C2 and the ACS contact. After disconnecting the ACS, the starter is disconnected. Such a starter controls the secondary voltage in all three phases in both manual and automatic modes.

The starter in Fig.6 works like this: when the gearbox is pressed, current passes through the current winding L1 and the current relay TP in the transit phase. The power contact in phase B closes and the contact TP opens. This makes it possible to turn on the winding L2, which closes the contact in phase C. The starter is on.

There are two ways to turn off the starter: either bypass L1 with the KS button or open any phase with the KST button / both sub-options are shown /.

In case of loss of current in the wire "a", the contact of the current relay TP closes, the L2 winding is bridged, the contact in phase C opens, L1 de-energizes and the starter trips.

If the current in the wires “in” or “c” disappears, L2 or L1 will be de-energized, respectively, which will lead to the disconnection of another contactor. The starter will shut off.

The proposed two-phase starter will be approximately 1.5 times lighter, cheaper, more reliable than a three-phase starter of the same "magnitude". Options 4 ÷ 7 protect the motor from out-of-phase operation.

Claims (4)

1. A starter for electric motors connected by a triangle, consisting of a mechanical electromagnetic system and a two-contact contactor, characterized in that the winding of the two-contact contactor is connected to the transition phase and to another phase after its contact or to two phases after its contacts through a series-connected symmetrical diode transistor and the stop button, and in parallel with the contact (s), there is a one-contact or two-contact start button, respectively, or te a start winding. 2. A starter for electric motors connected by a triangle, consisting of contacts and a mechanical electromagnetic system, characterized in that it consists of two one-contact contactors, and one phase is supplied to the electric motor in transit, and the winding of one single-contact contactor is connected to the transit phase and to the second phase after the power contact, moreover, this contact is switched to the third phase, and the winding of the second one-contact contactor is connected to the transition phase and the third phase through the "Stop" disconnect button, and This contact contacts the second phase, and the starter also has a closing start button, which shunts the power contact in the third phase, or one of the contactors has an additional starting winding. 3. The starter according to claim 2, characterized in that the winding of one single-contact contactor is connected through the symmetric diode thyristor to the transition phase and to the second phase after power contact, and this contactor switches the third phase, and the winding of the second one-contact contactor is connected to the transition phase and to the third phase through a symmetrical diode thyristor and a stop button connected to it in series, and the second phase is switched by this contactor, and the starter also has a start button, which shunts the forces A new contact in the third phase, or one of the contactors has an additional starting winding. 4. A starter for electric motors connected by a triangle, consisting of contacts and an electromagnetic system, characterized in that it consists of two single-contact contactors with current windings through which the operating current of the motor passes, and the mutual contact of one of them is connected in series to the winding of the other, and in the circuit of the transition phase there is a current relay, the opening contact of which shunts one of the windings, and the starter has a start button, a bypass of one of the contacts, has a stop button, untiruyuschuyu one of the windings, or an NC button "Stop" in any phase.

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