DE561196C - Arrangement for the automatic synchronization of asynchronous motors - Google Patents

Description

GERMAN EMPIRE

ISSUED ON
OCTOBER 11, 1932

REICH PATENT OFFICE

PATENT LETTERING

CLASS 21 d ² GROUP

Patented in the German Empire on November 25, 1930

The invention relates to such automatic synchronization arrangements of asynchronous motors by connecting an excitation winding arranged on the armature to a direct current source after the start-up, in which the direct current source and the circuit including the excitation winding is an electromagnetic contactor is switched on, which keeps the circuit open in the excitation state until the motor slips on one certain value has decreased. The subject of the invention is an arrangement this kind, in which the synchronization in a new way in a particularly reliable way and is achieved in a simple manner.

In the drawing is a circuit diagram of an embodiment of the subject of the invention forming arrangement

ao, which is a synchronizable Three-phase motor acts.

A denotes the primary winding which generates the rotating field of the motor and which can be connected to the three-phase network C via a switch provided with a switching drum B. The switch is provided with ten short-circuit fingers labeled 1, 2, 3, etc., of which those labeled 1, 3 and 5 are connected to the three-phase network C and those labeled 2, 4 and 6 are connected to the primary winding A. . The shift drum B, in which three angular positions marked I, II and III are to be distinguished, is provided with two conductively interconnected current connection strips b ¹ , b ² , b ³ , which in positions II and III each have a connection between the fingers Make 1, 2, 3, 4 and 5, 6. The armature of the motor carries a three-phase winding D _1, just like the primary winding ^, which is connected in the usual way to a starting resistor .E by three lines d ¹ , d ² and d ^3. The armature winding D also forms the excitation winding which can be connected to the direct current source for the purpose of synchronizing the motor, it being assumed that the motor can be synchronized as soon as the slip is only 1 ° / ₀ or less. A generator F, one terminal of which is connected to the current-fault finger 8 by a line G, serves as the direct current source. The other terminal of the generator F is connected by a line H to two current connection pieces h ¹ and h ^z of a switch designed as an electromagnetic contactor. The current connection pieces h ¹ and h ² are two current connection pieces i ¹ and k ¹ opposite, which through

*) The patent seeker stated as the inventor:

Or.-Ing. Ludwig Schön in Essen,

Cables! and K are connected to lines d ^s and dr , respectively. The line d ¹ is connected to the current-fault finger 7 by a line L. The two fingers 7 and 8 correspond to two electrically interconnected current connection strips & * on the shift drum B , which establish a connection between the fingers 7 and 8 only in the position III.
The electromagnetic contactor. is provided with an armature JV which is under the action of an excitation winding M and which, when the excitation winding M is de-energized, is held in a position by a tension spring P acting on it and acting in the direction of the arrow χ , in which it removes the current connection pieces h ¹ , i ¹ and h ² , k ¹ connects each to a contact piece n ¹ and n ^{2 seated on it.} A non-inductive resistor Ai ^{1 is} connected in parallel to the excitation winding M and is connected by a line Q to the terminal of the generator F connected to the line H and to the finger 9 by a line R. The finger 10 is connected to the other terminal of the generator F by a line 5. The two fingers 9 and 10 correspond to the shift drum B two conductively interconnected Strornschlußstreifen b ^5, which connect between the fingers 9 and 10 only in the position II. In the I position, all fingers are out of contact with the associated current connection strips. When the exciting coil M of the electromagnetic contactor M n ₁ N ¹ n ^2, h ^1, i ^1, h ^2, k ¹ by way of Q, M, R ₁ 9, ^s b, το, S communicates with the generator F in compound , the armature JV, as shown in the drawing, is held in opposition to the action of the spring P taking place in the direction of the arrow χ in a position in which the contact pieces n ¹ and n- are separated from the current connection pieces h ¹ , i ¹ and h ² , k ^{1 are} lifted. A multi- phase auxiliary motor designed as a three-phase motor is connected to the motor _{A 1} Ό and is provided with a primary winding T which generates the rotary field. This is through a line t ¹ to the line d ^1, t ² through a line to the line d ^2, and by a conduit ^s t to the line d ^s in connection. The line f contains a switch with two current connection pieces t ^l and the line t ^s a switch with two current connection pieces ^{t 5} . The current connection pieces i ^l are connected by a contact piece n ^s seated on the armature JV and the current connection pieces i ^{5 are connected by a contact piece? J 4} also seated on the armature JV, when the contact pieces n ¹ and n ² under the action of the field winding JIi of the Current connection pieces h ¹ , i ¹ and h ² , k ^{1 are} lifted, and are out of connection with each other when the pawl n ¹ and n ² rest on the current connection pieces h ¹ , i ¹ and h ² , k ^1. The armature of the auxiliary motor is seated on a shaft ^r U ₁ serving of a known automatic, periodically acting circuit breaker to the drive. The circuit breaker consists of a sleeve U ¹ fastened to the shaft U , which carries at least two circumferentially successive ring pieces u ² and ³ consisting of conductive and insulating material, and two brushes V ₁ which alternate when the shaft U rotates rest on the conductive ring piece u ² or the insulating ring piece u ^3. One brush is connected to the line S by a line V ¹ and the other brush is connected to the line R by a line V ² .

If the primary winding T of the auxiliary motor is connected to the armature winding D of the main motor, the three-phase current generated in the winding D also flows through the winding T, and this current has a frequency corresponding to the slip of the main motor - the auxiliary motor T ₁ U is therefore running the slower the smaller the slip. If, for example, the three-phase network C has the frequency 50 and the slip has dropped to 1%, the auxiliary motor runs at the speed 30 per minute, so that the shaft U takes 2 seconds to complete a full revolution. The circuit F ₁ -Q ₁ M ₁ M ¹ , V ² , V ₁ V ^ ₁ S ₁ F containing the excitation winding M of the switching protection therefore remains without if the brushes V _1, as in reality deviating from the drawing Angular distance side by side on the ring pieces. iP or u ^z , on the ^{circuit breaker JJ 1} , V alternately closed for 1 second and opened for 1 second. The conditions in the excitation circuit F ₁ . Q ₁ M ₁ M ¹ , V ² , V ₁ V ¹ , S ₁ F are now, in particular by lamination of the armature JV and a suitable choice of the size of the inductive resistor JW ¹ lying parallel to the excitation winding M , so that on the one hand the current strength After closing the circuit on the ring piece u ² very quickly in a fraction of a second the amount required to adjust the switch support is reached, on the other hand, after opening the circuit on the ring piece u ³ in the line M ₁ M ^{1 that} remains closed, even longer than ι second a sufficient current to hold the armature JV remains. So as long as the auxiliary motor makes more than revolutions per minute, the armature JV remains permanently in its position shown in the drawing, in which the line

device H, K, J is interrupted, and the armature only closes this line when the speed of the auxiliary motor has become less than 30 revolutions per minute, i.e. the slip of the main motor has fallen _{below i ° / 0.}

Before starting the main motor A, D , the shift drum B is in position I, in which all current-fault fingers 1 to 10 are out of connection with the strips b ¹ to b ^s . "When the shaft of the auxiliary motor located as well as the main motor at rest T, U has an angular position U, in which the brush V on the conductive annular member u- rest, the excitation coil M of the electromagnetic contactor M, N on the path Q ₁ M ₁ V ² , V ₁ V ¹ , S connected to the direct current generator F , and the armature Λ ⁷ is therefore held in its position shown in the drawing, in which the contact pieces n ¹ and n ² from the current connection pieces W, i ¹ and h ² , k ^{1 are} lifted and the contact pieces n ³ and w ⁴ connect the current connection pieces ί ⁴ and t ^s . If, on the other hand, the shaft U is in an angular position in which the brushes V rest on the insulating ring piece u ³ , then the field winding is M currentless, and the armature N is under the action of the spring P in a position in which the contact pieces n ¹ and n ² rest on the current connection pieces W, i ¹ and h ² , k ¹ and the contact pieces n ³ and M ⁴ of the current connectors ί ⁴ and ί ^{5 are} lifted.

To start the main engine, the shift drum B is first brought into position II, in which the excitation winding A is connected to the three-phase network through the strips b ¹ to b ³ and the strips b ⁵ connect the lines R and 6 ″. The excitation winding M des Contactor M ₁ N is now connected to the direct current generator F on the way S ₁ 10, b ⁵ , 9, R ₁ M ₁ Q , so that the armature N ₁ if it was in the position in which (deviating from the drawing ) the contact pieces n ¹ and ti ² rest on the current connection pieces i ¹ , W and k ¹ , h ² and the contact pieces n ³ and n * are lifted from the current connection pieces fl · and t ⁵ , in the position shown in the drawing, in which the excitation winding T of the auxiliary motor T, U is connected to the armature winding D of the main motor. The main motor now starts up, as does the auxiliary motor connected to the armature winding D. When the main motor starts up, the slip is initially very large, and the Shaft U of the auxiliary motor therefore turns very quickly. Therefore, due to the above-described selection of the ratios in the excitation circuit F, Q, M ₁ M ^1, V ^2, V ₁ V ^1, S ₁ F remains after at further rotation of the shift drum B in the position III the circuit F ₁ S 10, b ^s , 9, R ₁ M ₁ Q, F has been interrupted at 9 and 10, the armature N is also in its position when the insulating ring piece u ^{3 is} under the brushes V. Only when the slip of the main motor is less than 1% ^and the speed of the shaft U is correspondingly less than 30 revolutions per minute does the armature N drop out and close the lines at the current connectors h 1 and h ² , k ¹ H ₁ J and H ₁ K. At the same time, the contact pieces n ^s and n ^{l are} lifted off, so that the auxiliary motor is switched off and immediately comes to rest. By now III in the position reached shift drum B is now by means of the strip and ⁴ of the circuit F, G, 8, b \ 7, L ₁ d ^1, D ₁ D ^2, K ₁ k ^1, n ^2, h ^2, d ³ , J ₁ i ¹ , n ¹ , W-, H, F have been closed so that the armature winding D is connected to the direct current generator F; it therefore now acts as the excitation winding of a synchronous motor, so that the main motor continues to run as a synchronous motor.

Claims (4)

Patent claims: 1. Arrangement for the automatic synchronization of asynchronous motors by connecting an excitation winding arranged on the armature to a direct current source after the end of the start-up, in which an electromagnetic contactor is switched on in the circuit containing the direct current source and the excitation winding, which keeps the circuit open in the excited state, until the slip of the motor has decreased to a certain value, characterized in that the excitation winding (M) of the contactor is connected to a direct current source (F) via an automatic, periodically acting circuit breaker (U ¹ , u ² , u ^a , V) , which sits on the shaft (U) of a polyphase auxiliary motor (T, U) connected to the armature winding (D) of the asynchronous motor (A, D). 2. Arrangement according to claim 1, characterized in that the excitation winding (M) of the contactor is parallel to an induction-free resistor (M ¹ ) . 3. Arrangement according to claim 1, characterized in that the auxiliary motor (T ₁ U) can be switched off by the armature (N) of the contactor during the transition from the start-up to the operating position. 4. Arrangement according to claim 1, characterized in that a switch (Β) is used for the connection of the main motor (A, D), through which in an intermediate between position (II) the field winding (M) of the contactor can be temporarily connected to the direct current source (F) independently of the circuit breaker (U ¹ , V) , so that the field winding (D) of the main motor (A ) that can be connected to the direct current source (F) , D) can only be connected to the direct current source (F) in the end position (III) of the switch (B). For this purpose ι sheet of drawings