DD267171A3 - CIRCUIT ASSEMBLY FOR INFLUENCING THE CYLINDER SPEED IN CRANES - Google Patents

Abstract

The invention relates to a circuit arrangement for influencing the lowering speed in cranes whose hoists are driven by Schleifringlaeufermotoren. The object of the invention is to automatically influence the lowering speed of the load as a function of the latter. According to the invention, this was achieved by storing the respective current consumption of the hoist motor in hoisting operation via stepped comparators by subordinate AND gates and passing them as a signal of particular significance to a respectively assigned polarized relay with two stable layers during subsidence. The contacts of the polarized relays influence the phase control of a thyristor controller, which adjusts the direct current for braking the lifting motor in relation to the load in conjunction with a rectifier. Fig. 1

Description

For this 2 pages drawings

Field of application of the invention

The invention relates to a circuit arrangement for influencing the lowering speed in crane systems whose Hubworke be driven by slip ring motors.

Characteristic of the known technical solutions It is known that the speed of slip ring motors for hoists on cranes by low-loss or

affect lossy speed points.

Thus, by changing the primary frequency, the synchronous angular velocity and thus the operating speed of the Slip ring rotor can be varied. The Mot or will be separated from the 50 Hz network and with a corresponding

low-frequency power source connected.

In the rotor voltage control, the rotor voltage becomes an external slip-frequency voltage source

specified. Thus, the voltage balance in the rotor circuit and thus the size of the nereinein particular load settling slip can be influenced arbitrarily.

Also known is the so-called dual-engine circuit, in which a motor with reverse rotation is connected to the network, the

is excited with direct current.

In addition to the well-known variably adjustable rotor resistors, pulley drives also use pulse-controlled actuators as actuators Resistors for use. Here, a diode rectifier is arranged in the rotor circuit of the motor, is in the Gloichstromkreir

a resistor intermittently bypassed by a contactless switch.

To set lower speeds, an induction brake is often coupled to the slip ring rotor. The mode of action corresponds approximately to a Zwoimotorenochaltung. Engine torque and braking torque are superimposed to

resulting torque. The setting of the speed is carried out via an additional resistor or a variable resistor in

Excitation circuit of the induction brake. Another circuit for adjusting and maintaining low speed in slip-ring motors operates in Connection with an electrohydraulic brake fan, which is controlled in dependence on the rotorfrequency,

that the braking torque always corresponds to the difference between motor and resistive torque.

As a result, the slip ring rotor always works with a constant threat number at the operating point, regardless of the size of the moment of resistance.

With the DD-PS 236216 a circuit arrangement for DC forced braking for hoists with slip-ring motors is set out, with which at the control switch position zero, the lowering load is decelerated so far,

d. H. the DC brake remains effective until the lowering speed is decelerated to about 20-25% of the nominal sinking speed and then the automatic switching to the mechanical holding brakes takes place.

In elnor thyristorparregelschaltung for Drehstromschleifringläufi, motors according to DD-PS 236632, which regardless of the load up to the max. Speed operates and controls within wide limits, thyristors are arranged in the star point of the rotor whose Steueroingänge are combined with einor control circuit. With DD-PS 224726 a circuit arrangement for speed control of asynchronous motors is described. In this case, part of the stator winding, which is not driven by the non-shifted operating current, is partially regulated by a part of the stator winding which is passed through by the phase-shifted operating current.

A further known circuit arrangement consists of the combination of switchable in stages rotor resistance and a DC braking, which is equally suitable for stopping the drive and for stationary braking pulling loads. Dor Slip Ring Motor is disconnected from the mains and the stand is powered by DC.

According to DE-OS 2059842 for dynamic limiting of a slip-ring rotor motor is a control of the motor speed in conjunction with a "Fühloinrichtung" as actual value.

In this case, the signal of a tachogenerator is compared with a reference signal as a setpoint and a controller with variable

Pulse ratio supplied. If the speed is exceeded compared to the setpoint, the stator phase winding is disconnected from the mains and the rectifier is switched off via the pulse controller.

If the setpoint is undershot, the stator phase winding wled jr is connected to the grid. The speed is thus kept constant by this changing switching of both switching states compared to the setpoint.

After dor DD-PS 209235 is also the detection of the ailing load on the motor current through a current transformer with downstream threshold value switches of different reference sizes known.

A disadvantage of the known technical solutions that they are too expensive to use for medium power drives up to about 30 kW, from Platzgründon not too realisleron or only with large conversion measures in existing cranes, or the type of Rogeiung for Hubmotore, both in the as well as working in the over-synchronous area, is unsuitable.

All solutions also have the disadvantage that the regulation of the lowering speed for positioning operations in passing loads irnrnoi manually and not automatically depending on the posted load.

Object of the invention

The aim of the invention is to provide a circuit arrangement with which eliminates the disadvantages of the known technical solutions, the lowering speed is influenced automatically analogous to the load and subjectively caused operating errors are avoided without limiting the safety.

Explanation of the invention

The object of the invention is to provide a functionally reliable circuit arrangement for influencing the lowering speed, which adjusts automatically after dor respective load of the lifting motor of Krananlago.

According to the invention, this object is achieved in that the outputs of comparators whose inputs are in a known manner via a measuring rectifier Sokundärausgang a arranged in the motor supply current transformer, are led to the inputs of the associated AND gate and the second inputs in parallel at the output of a Gate for signal delay are located in the input of the normally open contactor of the Hubbc'rieb is arranged, that the output of a high-order AND-Gsiters each connected to the negated input of the low-priority previous gate AND gate, and that all outputs of the AND gate via Amplifier to the respective working windings of the polarity relays with two stable layers, the other terminals are connected together to the normally closed contact of the contactor for Hubbetrii> and that the Arboitskontakte the gopolten relays each to one of the series resistors for the control of the thyristor Stellers are connected in parallel. The AND-G attor are beschaltot for signal delay for the duration of the switching time between working and normally closed contact by the contactor for Hubbetriob with one capacitor.

The Loistungsausgang the Thyristorstellers is connected to a rectifier whose Gleichstromausyang is located on the contactor for the DC braking operation and whose departure is performed with the departure dos contactor for three-phase operation together to the lifting motor.

In addition to the usual reversing contactor interlocking, the contactor coil of the contactor for three-phase operation is on a quiescent contact, and the contactor coil of the contactor for DC operation is connected to the control voltage via a normally open contact of the footswitch.

Ausführungsbelsplol

The invention will be explained in more detail below on a Ausführungsbelsplel. The accompanying drawings show

FIG. 1; The circuit diagram for the power section of the lifting motor

Figure 2: The block diagram of the circuit arrangement for regulating the Senkgoschwindigkoit

The circuit arrangement is developed for crane lantics, whose hoisting motors m 1, as slip-ring rotors, have a corresponding regolcharacter characteristic through the switching on and off of idler torches R10-R40 via contactors Q6-O9 or control devices. This characteristic is of the loadon to be lifted and dropped dependent.

The operated during the lifting of loads in ¹ subsynchronous Boreich lifting motor m 1 operates during the lowering of the aforementioned overhauling loads in the over-synchronous range.

Since the lowering speed is load-dependent, the rotor resistances R10-R40 always have an influence on the fine-step lowering operation with increasing load.

When one of the two contactors Q1, Q 2 for lifting or descent operation is switched off, the Elhyd brake motor m is switched off as well. by the contactor Q 5, the mechanical brake is effective and held the load.

This Elhyd brake m 2 is used as a safety device for passing Laston in the event of a voltage drop or power failure and other electrical faults within the controller. However, Sia has no influence on the influence of the sinking speed in the circuit arrangement according to the invention. The relationship between dr r averaged load and its lowering speed is dependent on the circuit arrangement of Gloichstrombremsmomont and thus the word dos on the lifting motor m 1 pending Gleichstromas. In order to determine this value in each case, it is assumed that each load to be lowered is first to be lifted, the current consumption of the lifting motor m 1 corresponding to the respectively applied load in the lifting operation.

This operating mode is initiated according to FIG. 1 by switching on the contactor Q1 and the contactor Q3 for three-phase operation.

At the same time, the contactor Q 5 is disconnected and the Elhyd brake motor m 2 is switched on, so that the mechanical brake of the lifting motor rn 1 is released.

According to the start-up conditions, the Löuforwidorstand R10, R20, R30, R40 is reduced by the contactors Q6-O9 in a known manner.

The capture of. Operating current for the Hubrnotor m 1 is carried out by the current transformer F, whose secondary winding is short-circuited by the burden resistor Rm. The voltage drop which occurs in the same proportion to the motor current serves as a measured variable, the processing of which is described with the circuit arrangement according to FIG.

For the normal lowering operation, the contactors 02, Q3 are actuated and the load is lowered. Before putting on the load, the contactor Q3 for the three-phase operation is switched off by actuation of the foot switch T and the contactor Q4 is extinguished for the DC braking operation. Thus, the separate from the network lifting motor m 1 of the rectifier G generated by the DC current is supplied, which was set on the three-phase side by the thyristor E with its, influenced by the circuit arrangement A phase control.

When handling the loads, however, the lifting operation is not directly the Senkbetriob, but is the operation of the lifting motor m1 interrupted by alternately operating the contactors Q1, Q2 and by the driving dor Krananlago.

This changing mode of operation is taken into account by the circuit arrangement of Figure 2, by the boim Hubbetriob ff by the current transformer for measuring and controlled variable is stored for a not immediately following Sonkbetrieb.

For this purpose, the analog alternating voltage applied to the applied load is rectified by the measuring rectifier Gm and fed in parallel to the actual word inputs of the comparators S1-S4 with graduated setpoint settings.

This binary division of the setpoints should correspond to the example of the selected load levels of 25/50/75 and 100% to the maximum actual value. At 80% load, the output signals of Komparstoren S 1, S2, S3 are applied to the inputs of the AND gates A1, A2, A3. Their second inputs are connected in parallel to the output of the gate A5 for signal delay, which is activated by the contact Q 1 from the contactor Q1 Hubbotrieb.

According to the example, since the high-order AND gate A3 leads its output signal, decoupled via diodes, to the negating inputs of the AND gates A2, A1, both AND gates A2, A1 are not turned on. The output of the AND gate A3 is at the same time connected to the amplifier V 3, the output of which is connected to the one end of the working winding 2 of the polarized relay I <3 with two stable layers.

Upon completion of the lifting movement by the contactor Q1, the normally open contact q 1 opens, the normally closed contact q 11 closes and the polarized relay K3 is energized. It takes its working position and bridges with its contact K3 the resistor R3 to control the TI .. ristorstollers E. The staggered according to the selected load levels values of the resistors R1-R4 change analogously to the phase control for the thyristor E and thus regulate the required DC for dan lift motor m 1 during lowering operation. Dio series connection of the resistors R1-R4 has the effect that the thyristor E remains active even if one of the contacts K1-K4 malfunctions. If the contactor Q1 is switched on again for the lifting operation, the quiescent contact q 11 lying in the circuit of the working windings 2 opens and the working contact q 1 is closed, causing the return windings 1 to be energized and the polarity relay in question, according to dom Boispiol K3, is brought into his Huhelage.

Since the load has not been changed, the VND gate A3 is again activated via the comparator S3 and the switching sequence described is repeated.

The capacitors C1-C4 at the AND gates A1-A4 cause a signal delay for the periods of the contact envelope from the Arboiti contact q 1 and the normally closed contact q 11 of the contactor Q1 including the starting time of the poled relays K1-K4.

In case of failure d st operating voltage which is in its working position gopolte relay K1-K4 also retains its position, which is changed only by a subsequent lifting operation.

Documents considered:

DD-PS 32459 (H 02 P, 7 / () 0)

DD-PS 209235 (F 16 D, 9/00}

DE-OS 2059842 (21 c, 59/58)

DE-OS 3312956 (H 02 P, 3/24)

VEM manual: The technique of electric drives (fundamentals), Verlag Technik Berlin 1963, p. 131

Claims (4)

1. Circuit arrangement for influencing the lowering speed in cranes according to the ailing load, the hoist is driven by a slip ring motor whose operating current through a lying in a phase of the motor supply current transformer, the secondary output is completed by a Bürdewidarstand, as a DC voltage value in conjunction with staggered setpoint Detected having comparators and AND gates, amplifiers, poled relays, contactors and a thyristor is processed, characterized in that the outputs of the comparators (S 1 -S4) to the one inputs of the associated AND gates (A1-A4 ) and whose second inputs are parallel to the output of a gate (A5) for signal delay, in whose input the normally open contact (q 1) of the protection (Q 1) is arranged for lifting operation, that the output of a high-order AND gate (A4, A3, A2) each with the negated input of the v lying lower-AND gate (A3, A2, A1) is connected and that all outputs of the AND gate (A 1-A4) via amplifiers (V 1 -V4) to the respective working windings \ 2) of the polarized relays (K1 -K4) lie with two stable rest positions, the other terminals (2) are guided together to the normally closed contact (q 11) of the contactor for lifting operation, and that the normally open contacts (k1-k4) of the polarized relays (K 1-K4) to each one of the series resistors (R 1 -R4) for the Staurerung the Thyristorstellers (E) are connected in parallel. 2. A circuit arrangement according to claim 1, characterized in that the AND gate (A1-A4) each with a capacitor (C1-C4) for signal delay for the duration of the switching time between normally open contact (q 1) and normally closed contact (q 11) of the contactor (Q 1) are connected for the lifting operation. 3. A circuit arrangement according to claim 1, characterized in that the power output of the Thyristorslellers (E) to a rectifier (G) is guided, whose DC output is connected to the contactor (Q4) for DC braking operation whose departure with the departure of the contactor (Q3) for three-phase operation together on the hoist motor (m 1). 4. The circuit arrangement according to claim 1 and 3, characterized in that in addition to the usual reversing contactor the contactor of the contactor (Q3) for three-phase operation via a normally closed contact, and the contactor of the contactor (Q4) for DC braking ühsr a normally open contact of the foot switch (T) to the Control voltage is applied.