DE470219C - Three-phase circuit for crane hoists - Google Patents

Description

The three-phase asynchronous motor has the disadvantage that the hoist operation Speed when moving the empty hook is practically no greater than at full load, while in the case of a direct current main current motor, the empty hook at twice the speed is lifted. Attempts have been made to remedy this disadvantage by using three-phase single-phase commutator motors to fix. However, can

to do not have enough effect on the series connection characteristics of these motors due to the very large armature moment of inertia. In addition, ^one such motors are very expensive, and its speed can not be increased sufficiently.

You can also increase the capacity of crane hoists, which are driven by three-phase asynchronous motors are driven, thereby increasing that with a slow running

äo main engine for lifting the full load is dimensioned, a motor running at 2 to 2.5 times the speed of lower power is coupled directly. The high-speed engine should essentially be used to

S5 must be used because of the empty hook and can be rated for the same duty cycle as the main motor because the empty one Hook has to cover practically the same distance as the full load with every game. Here it is important that on the one hand by the arrangement the operation of the control for the guide is in no way made difficult, and that on the other hand the control arrangement for operation with an auxiliary motor does not make such a change in the control rollers necessary that the usual rollers cannot be used. The first of these considerations would e.g. B. the use make two separately operated rollers impossible, and the second makes it impossible to design a single roller so, that the first part of the positions of the lowering and lifting side only for the control of the slow running and the last part set up for the control of the high-speed motor will.

The invention now relates to a particularly useful control of the auxiliary engine. This consists in that an adjustable auxiliary roller is provided in addition to a switching roller is, which in the one position intended for heavy loads only allows the control of the slow-running motor and in another position intended for light loads, the high-speed engine allowed to switch on. .

In order to achieve a brisk acceleration, the auxiliary roller is also set to

*) The patent seeker stated as the inventor:

Carl Schiebeier in Berlin.

470210

"Light loads" first of all, the slowly moving one Motor and only then the fast running end is switched on. In this way it is possible a motor with a short-circuit armature or with a slip ring armature and continuous slip resistance to use and save special starting stages for the fast running engine. When switching off, after switching off the fast-running one, the slow-running one ίο Motor reconnected to the mains. " So that there is no excessive braking shock and the machine falls out, is the switchover made in one position of the control roller, in which in the rotor circuit of the slow running motor are switched on. In order to avoid incorrect use of the high-speed motor for When lifting heavy loads, avoiding overloading is generally sufficient ao self-off switch. However, you can also turn on the small motor prevent a current monitor whose main current coil is in the ι circuit of the slow-running The motor is switched on and only if the current in the main motor is small enough enables the high-speed motor to be switched on. This facility is when lowering not usable because of the difference in the currents that occur. In this case, one can, provided that ' a slip ring motor with a permanent series resistor is used as the high-speed motor is exceeded by a voltage monitor excited by the auxiliary motor Avoid speed.

Often, especially with gripper hoists, it is required that the load, i.e. 2. B. the open gripper, can also slowly lower, in order to avoid a too hard touchdown on almost to avoid emptied ship or wagon floors. For this purpose the controller can easily expanded by adding a third position on the auxiliary roller be, on which the motor is switched on in the lifting sense with the involvement of such a large resistor that the empty gripper is not raised, but slowly lowered. .

An embodiment of the invention is shown in FIG. To simplify operation, the auxiliary roller is adjusted here by moving the control lever η of the main roller in the horizontal slot (Fig. 2), while the lifting and lowering of light and heavy loads takes place in the vertical slots. The mode of operation of the circuit in the individual work processes is explained using the designations selected in the figure. In the "heavy loads" position of the auxiliary roller c, when the main roller a is switched to the lowering side through the circuit from the mains phase R, via the contact finger s, the left auxiliary contacts of the reversing contactor for the high-speed motor /, the lowering contactor s, the right auxiliary contact of the lifting contactor h, the main motor d is switched on in the lowering direction during the mains phase T. At the same time, the brake ο is released through the contact strip for the brake contactor b . When the main roller is switched on, the starting resistors are first short-circuited and the load is accelerated. In positions 5 to 9, the resistors are switched upstream again and the motor is controlled in over-synchronous operation when loads are pulled through. From position 7 on, a contact coating is provided which is intended to excite the lowering contactor via the contact finger s' in order to switch on the high-speed motor. In the "heavy loads" position of the auxiliary roller, however, the supply line to the contactor s' and the phase T- is interrupted; the contactor cannot start, and positions 7 to 9 are also used to regulate the main motor. When switching back it is achieved by known devices that the short circuit of the starting resistors reached in position 5 is maintained until the zero position. During the transition from position 6 to 5, the auxiliary roller g is automatically brought into the position in which a; Short circuit of the points x / y, u, ν im, rotor e is established. . When switching on the lifting side for lifting heavy loads, the "contact strip for contactor A" of the high-speed motor is also ineffective, since the supply line to the contactor and phase T is also interrupted "Loads" the lowering contactor s' or the lifting contactor 'h' is energized and switches the high-speed motor / on to position 7 or 5. The left auxiliary contacts of the contactor s ' and h' then interrupt the circuit for the stator contactor s or h of the main motor and switch it off.

In position III of the auxiliary roller, when the main roller is not switched on, the main motor is given a constant countercurrent braking torque corresponding to a certain load; the control lever ti (Fig. 2) slides into the slot in the slot basket, which is slightly off-center. The contactor h of the main motor and the brake magnet ο are switched on by the contacts R, h, b of the auxiliary roller. In addition to the starting resistors, the special additional resistors / ₁₅ - * ie and r ^ -r ^ are connected to the rotor circuit. In positions I and II of the roller, these resistances are bridged by contacts in the auxiliary roller.

Claims (3)

Claims: i ι. Three-phase circuit for crane hoists with a slow-running Mo- j high performance torch and a high-speed motor directly coupled to it i lower power, characterized in that in addition to the switching of the long j The main roller present with the running motor is an auxiliary roller which can also be adjusted with the control lever of this roller is provided that when set to a position intended for heavy loads only enables the control of the slow running motor when operating the main roller and after setting on another position intended for light loads only after the actuation of the slow running motor allowed to turn on the fast running motor. 2. Circuit according to claim ι and 2, characterized in that the activation of the high-speed motor when lifting is only possible if the amperage is in the slow-running Motor does not exceed a value corresponding to the permissible light load. 3. A circuit according to claim 1, characterized in that on the auxiliary roller a third position for slow lowering of heavy loads with countercurrent is provided in which the main motor is switched on in the lifting direction. 1 sheet of drawings