Patent GB-191311313-A (GB)
Title: Improvements in or relating to the Control of Alternating Current Commutator Electric Motors.
IPC: H02K27/28
Filed: 1913-05-14
Granted: 1914-04-30
Abstract: 11,313. Siemens-Schuckertwerke. May 14, 1912, [Convention date]. Alternating-current commutator machines.-In intermittently-working three-phase commutator motors, such as winding-motors, in which the speed is controlled by shifting the brushes, and the rotation is reversed by changing the phase connexions of the stator, the switching-in of a resistance in series with the stator for regenerative braking is made to depend upon the position of the brushes and that of the stator reversing-switch. In the two-lever control shown in Fig. 1, the stator reverser q of the motor 1 is linked to an auxiliary lever l, which also controls, through an arm k and link i, the position of a rod f in a slotted plate e carried by the main lever a. The rod f controls the switch h of the brake resistance, and the lever a is geared at d to the brush-rocking gear. With the lever l displaced to the left, as shown, the stator switch q is closed, the rod f being at the top of the slot. Displacement of the lever a to the left moves the lever g and closes the switch h so as to energize the stator in one direction without including the resistance. At the end of the wind, the lever a is brought to the right and the lever g causes the switch h to include the resistance for braking after the brushes have passed the pole centres. For the reversed wind, the lever l is moved to the right to change the stator phases at q, the rod f being simultaneously dropped to the bottom of the slot. Movement of the lever a to the right then starts the motor, and movement to the left inserts the resistance for braking. In the single-lever device shown in Fig. 3, the lever l can move in a plate p in either of two guide-slots p<1>, p<2>, joined by a cross slot, and it passes through a transversely - movable slotted member r, which is coupled to the stator reverser. The brushes are controlled by the rod s'. Movement of the lever in one slot or the other controls the rotation of the motor in one or the other direction. Single and double arms e, z, pivoted on 'the bearings of the shaft s, are connected at s<2> to the switch of the brake resistance, and the lever l, by pressing on these arms, inserts the resistance when it is moved towards the left in the slot p' and towards the right in the slot p<2>. A single lever s, Fig. 4, moving in one plane and controlling the brushes and the stator reverser u<1>, may be employed in conjunction with an auxiliary device, which in this case consists of a polarized direction-indicator z attracted by one or other of two magnets m<1>, m<2> which are energized by a dynamo on the motor shaft. The indicator is coupled to the switch b' of the braking-resistance w, a three-way switch b<4>, and a second reverser u<2>. The reverser u<1> is opened by a switch a when a magnet m is energized. When the lever s is moved to the right, say, to start a wind, the switch b' moves to the right and the switches b<2>, u<1> to the left. Current passes through the central contacts at b<4> and the motor starts. The indicator is drawn to the right and moves the switches b<3>, b<4>, u<2> to the left, no circuit being made through the resistance w. The momentary parallel connexion of the switches u<1>, u<2> is broken by the magnet m. If now the lever s be brought to the left, the circuit at b<2> is broken and one is made through the switches b<1>, b<3> and the resistance for braking. When the motor comes to rest, the indicator opens the switch b<3> in readiness for the next wind. In the arrangement shown in Fig. 5, a centrifugal auxiliary device g is used. The control lever s is linked to a three-armed lever at c, one arm e of the lever being coupled to the brushes. The third arm d can enter a recess l in a block m which is suspended from the device g at s', s<2> and which has a tooth n adapted to enter either of two notches k<1>, k<2> in a fixed part p. The block m is linked to the resistance switch b<3>, a switch b<4>, and the reverser u. When the lever s is moved to the right, say, the block m and switches b<2>, b<3>, b<4> move to the left. The motor starts, with the resistance w out of circuit, and the device g lifts the block, which leaves the arm d and engages with the notch k<2> as long as the motor is running. Further movement of the lever s controls the brush position only, but when the lever is moved to the left of its central position, the circuit is broken at b<2>, b<4> and made at b', b<3>, leaving the braking-resistance in circuit as long as the motor revolves.