DE962184C - Safety device for the correct phase connection of mobile systems - Google Patents

Description

ISSUED APRIL 18, 1957

B 3ioi3VIIIb / 2ic

Heinz Lebert, Mannheim

has been named as the inventor

In portable systems that work with three-phase motors, it is often the case that that it is not clear from the outset in which order the individual phases of the network the facilities are affiliated to soMeni. It. consists hence the risk of the connection being made with the wrong phase sequence.

In themselves, devices are used to display the correct or incorrect phase sequence of a connection to be connected Network known. What is desired, however, is a device that does not provide a display, but an output power, with which a circuit or a locking of a switch-on contactor automatically is made.

On the other hand, arrangements are also known that work with a motor relay that at correct phase position and operational readiness of all three phases keeps a switch closed and opens the switch in the event of a malfunction.

The known arrangements generally consist of numerous mutually movable Sharing is very prone to failure due to the necessity of such a mutual movement. It should therefore be sought by the invention, the circuit for the switch and locking of the contactor to be controlled as contactlessly as possible and without moving parts. The parts used should be as simple, durable and cheap as possible, in particular Common components should be used for the necessary circuit.

It has now been shown that this task by means of resistors and inductors in the Way can be solved with advantage that the

Coil of the contactor with one pole connected to one phase via an ohmic resistor and is connected to the second phase via an inductive resistor (choke coil), while the other pole of the magnetic coil of the contactor to the center tap of an adjustable Transformer or a variable resistor is connected between the third and second phase is switched. ίο The circuit used is particularly useful, if the ohmic and the inductive resistance are in the interlinking line of the two Phases are balanced against each other in such a way and the transformer or the variable resistor so it is set so that the two currents flowing through the contactor are mutually connected with the correct phase connection essentially cancel the system.

If the compensating voltage is taken from an adjustable transformer, the Usually the transformer is switched between the third phase and the phase that is connected to the solenoid of the contactor is connected via the choke coil.

If the contactor is designed as an auxiliary contactor, it is possible to use the entire relay with the resistors and to combine the choke coil into a closed component.

In a further embodiment of the invention, such an arrangement is when using two Protect according to the design as phase sequence relay Can be used if the inductive and ohmic resistances in the supply line to the individual shooters are swapped in their order and at the same time the assignment of the through the individual contactors actuated switch is selected accordingly.

In such a case, there is preferably an additional three-pole contactor with each contactor Auxiliary switch connected, which locks the activated contactor as long as the switching status the system remains unchanged. The electrical locking of the one Contactor by automatically switching off the branch line belonging to the contactor, in particular the choke coil.

The mode of operation of the circuit is initially on

a simple relay based on Figs. 1 and 2 and the vector images Fig. 3 to 6 explained in more detail.

By connecting a resistor R and a choke coil L in series , the linked voltage between two phases (e.g. S and T)

divided into two voltages U _R and U ₁ .

A voltage U _AR then prevails between the tapping point A and the other phase R , which is applied in the direction of a voltage Ur _x by appropriately dimensioning the resistor R and the inductor L.

A transformer or variable resistor connected between phases R and T is connected with its control tap to the contactor in such a way that the current flowing through the contactor is approximately zero when the motor is connected in the correct phase.

If the phases S and T are mixed up, then a voltage arises between the point and the tap of the transformer or control resistor, which, however, is significantly greater than in the first case. This voltage is easily sufficient to control the corresponding contactors or auxiliary contactors. Thus, while in the illustrated embodiment the contactor remains at rest if the connection is in the correct phase, it will cause the network to be switched off if the connection is incorrect. In principle, it would also be possible to dimension the choke coil and the resistor in such a way that the power supply is switched on when the position is correct, while the contactor does not operate when the power is off or when the connection is incorrect.

It is particularly useful to use two such contactors interchanged with one another arranged resistors and reactors, so that when connecting the system to a network responds to at least one of the two contactors and in this case the one with the correct phase Connecting the system. Then it is possible to build the circuit so that the adjustable transformer or the rheostat to produce an auxiliary voltage in Omission can come.

In Figs. 7 to 9 the mode of operation of a phase sequence relay switched in this way is shown shown in detail:

Fig. 7 shows the phase sequence relay in the ready-shaft position with the mains switched off, ie with the main switch H open. The two circuit breakers P ₁ and P ₂ , which interchange the phase sequence and are controlled by the contactors S ₁ and S ₂ , are open. In the circuits which connect the phase with the contactors ^ and S ₂ , two three-pole auxiliary switches Q ₁ and Q _{2 are} provided, the switching elements of which are arranged in such a way that the direct supply line from one phase to the contactors is interrupted, but the other current paths are closed.

If the main switch H is now inserted (Fig. 8), phase 5 "in the circuit shown meets the resistor R ₁ of one contactor ^ ₁ and the choke coil L _{2 of} the second contactor S ₂ , while phase T with the choke coil L _{1 of} the first contactor S ₁ and is connected to the resistor ^ of the second contactor S _{2. In} the exemplary embodiment shown, the choke coils and resistors are matched to one another so that the contactor V ^ ₁ receives current, while the contactor S ₂ The residual current flowing is not sufficient to make this contactor respond.

A current then flows between the phases R and 5 "via the resistor Ji ₁ , the tapping point A ₁ and the contactor S ₁ , which is excited in this way and moves into the switching position shown in FIG.

The circuit breaker P ₁ is thereby closed and thus the desired phase

correct connection of the consumer V to the network RST established. At the same time, the three-pole auxiliary switch Q ₁ switches the contactor S ₁ directly between the phases R and 5 ″ and thereby electrically interlocks it until the main switch is opened, i.e. the mains is switched off the contactor is limited.

ίο is energized, the contactor, so the auxiliary switch Q is interrupted at the same time the current through the balancing means R _1, L _{1 1} by the two other switching elements.

If the phase is reversed for any reason on a new connection, then when the main switch is switched on, contactor S ₂ , which is matched to the reversed phase, responds, it closes circuit breaker P ₂ and reverses the phase for consumption connection V.

ao The auxiliary switches Q ₂ then lock the contactor S ₂ accordingly and make the circuit de-energized via the balancing device R ₂ , L ₂ until the mains is switched off.

In this case, the interlinked voltage U _{ST is divided up in} such a way that the lowest possible residual voltage is set. This residual voltage then has a magnitude at which an AC contactor no longer responds and the coil current is no greater than the normal operating current. Since one of the two contactors responds in any case, whereby all other circuits are interrupted, the adjustable transformer or control resistor required for the simple relay is unnecessary in the case of the phase sequence relay. The switching sequence of the relays can have the opposite effect by interchanging the connections. The relays then switch when the phase position is incorrect and remain at rest when the phase position is correct.

In principle, capacitors of corresponding dimensions can also be used instead of the choke coils to be used.

In addition, the invention is not limited to the two illustrated embodiments, but can also be done in another way by dividing the chained tension between be carried out in two phases.

Claims (7)

Patent claims: i. Safety device for the correct phase connection of portable systems to a three-phase network by means of detachable electrical connections by switching off of the three-phase motor from the mains if the phase is incorrectly connected or fails, in particular for motors of mobile refrigeration systems, characterized in that the coil of a contactor with its one Pole to one phase via an ohmic resistor and to the second phase via an inductive resistor (choke coil) is connected, while the other pole of the Magnet coil of the contactor to the center tap of an adjustable transformer or a variable resistor connected between the third and second phases is. 2. Apparatus according to claim 1, characterized in that the ohmic and inductive Resistance in the interlinking line of the. both phases and the transformer or the The rheostat is set so that the current flowing through the contactor is correct in phase Connection of the motor approximates to zero ". 3. Device according to one of claims, 1 and 2, characterized in that the contactor is designed as an auxiliary contactor and with the Resistors and the choke coil is combined to form a closed component. 4. Device for automatic phase-correct switching on of a three-phase motor to the network using two contactors according to Claims 1 to 3, characterized in that that the inductive and ohmic resistances in the supply line to one contactor and in that to the second Contactor are interchanged, as is the assignment of the individual Contactors operated switches. go 5. Apparatus according to claim 4, characterized in that with each contactor still an additional three-pole auxiliary switch is connected to the activated Contactor locked as long as the switching status of the system remains unchanged. 6. Apparatus according to claim 5, characterized in that the electrical lock of the one contactor with the elimination of the adjustable transformer or the regulating resistor by automatically switching off the adjustment lines belonging to the contactor and directly connecting the Contactor to the line-to-line voltage. 7. Device, in particular phase sequence relay, according to one of the preceding ¹ claims, characterized in that the choke coil is replaced by an appropriately sized capacitor. Considered publications:
AEG-Handbucib, Essen 1949, pp. 445, 446;
H. Titze, "Fehler und Fehlererschutz", Vienna ^Χ 953> p. 92, paragraph 2, especially fig. 86 and 87; W. Lehmann, "Electrical engineering and electromotive drives", Berlin 1948, p. 245, Fig. 581; P. 291, fig. 681; P. 341, fig. 768. For this purpose 2 sheets of drawings © 609 659/570 10.55 ■ (609 863 4.57)