CS250155B1 - Wiring for rotor phase indication of asynchronous ring motor - Google Patents

Abstract

The solution is particularly suitable where two or more ring motors work in a mechanism that connects them mechanically, either rigidly or flexibly, and where the smallest possible slip is required. The monitoring of fault conditions is derived in individual phases from the shunts included, from which the signal is processed through rectification, filtration to a measuring amplifier, which operates using a limiting circuit into a universal transistor relay, with high input impedance, its own effective filtration and with the possibility of continuously changing the holding ratio of the output relay. The sensitivity can be adjusted, for example, so that a current drop below 0.25 I of the nominal is indicated.

Description

The invention relates to a circuit for indicating the phase currents of an asynchronous ring motor rotor which should run with minimum slip. In these cases, it is not possible to leave a permanently engaged slip resistance to obtain a sufficient signal to indicate the rotor current.

Monitoring the rotor currents of the individual phases has its merit in cases where two or more motors operate in a mechanism that mechanically connects them to each other, either firmly or flexibly, e.g. conveyor belt.

Direct monitoring of rotor currents has not been performed yet, as it is difficult to indicate the voltage with a slip frequency of 1 Hz. An interruption of some phase of the rotor circuit results in parasitic moments, but the mechanically overloaded motor and ee rotate.

The problematic indication of rotor failure can only be done by monitoring the stator winding loads of individual motors. The above-mentioned disadvantages are eliminated by the circuit according to the invention, which consists in that shunts are connected to the individual rotor phases of the asynchronous ring motor.

One shunt outlet is connected to single-pulse rectifier diodes and also to input resistors, the other end of which is connected to the first terminals of the filter capacitors and simultaneously to the inputs of the measuring amplifiers. The second shunt outlet is connected to the second outlets of the filter capacitors and simultaneously to the second inputs of the measuring amplifiers.

Outputs of the measuring amplifiers are connected to inputs of universal transistor relays for phases M, L, K. Loads of resistors and limiting circuits consisting of Zener diode limiting circuits are connected in parallel between inputs of individual universal transistor relays.

The wiring indicating the phase currents of the asynchronous ring motor rotor processes losses on permanently arranged sidewalls in the rotor circuit. Shunt voltage Is applied after single-pulse rectification and filtering to the measuring amplifiers. BRIEF DESCRIPTION OF THE DRAWINGS The invention is schematically illustrated.

The ring asynchronous motor 1 comprises permanently connected brushes to which three shunts 2 are connected. The voltages from the filter capacitors 5 are fed to the inputs of the measuring amplifiers

The outputs of the measuring amplifiers 6 are fed to the load resistors 2 and to the inputs of the universal transistor relays 10, 11, 12 for the phases M, L, K. At the same time the outputs of the measuring amplifiers 6 are fed to eventually with them - series of fine-tuning diodes 1 ·

The function according to the invention is as follows: From the voltages of the individual shunts 2e, the diodes J provide a single pulse rectification, these diodes must have the least drop in the forward direction. The rectified voltages are applied to the RC elements, which form the input resistors a and the filter capacitors χ. The filtration efficiency is given by the ratio of the load impedance of the filter capacitors 2 to the charge impedance. In this case, my ratio is three orders of magnitude, which allows the measuring amplifiers á, which at the same time have a certain possibility of current overload of the outputs.

Outputs of measuring amplifiers are connected to inputs of universal transistor relays 10. 11. 12. own effective filtering and possibility of continuous adjustment of holding ratio of output relay. Load resistors 21 are connected to the outputs of the measuring amplifiers 6, which operate roughly in the range corresponding to the rated current of the ring asynchronous motor with permanently connected brushes.

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In the case of an overcurrent during start-up, the limiting Zener diodes 8, possibly the fine-tuning diodes 2, are applied, whose connection doregulates the Zener voltage. This arrangement can be achieved, it can be indicated in various stages of the rotor current drop below 0.25 I _n though this current varies with the slip frequency to 0.2 Hz. For exposed drives it is advisable to monitor rotor currents even for ring motors working separately.

Claims (2)

SUBJECT OF THE INVENTION Wiring for indicating the phase currents of an asynchronous ring motor rotor with permanently connected brushes, characterized in that: in the individual rotor phases of the asynchronous ring motor (1) shunts (2) are connected, whereby each shunt outlet (2) is connected to diodes ( 3) single pulse rectification and further on the input resistors (4), the other end of the input resistors (4) being connected to the first terminals of the filter capacitors (5) and simultaneously to the inputs of the measuring amplifiers (6), to the second terminals of the filter capacitors (5) and simultaneously to the second inputs of the measuring amplifiers (6), the outputs of the measuring amplifiers (6) being connected to the inputs of the universal transistor relays (10, 11, 12) for M, L, K inputs of individual universal transistor relays (10, 11, 12) are connected in parallel with load resistors (9) or circuits consisting of Zener diode limiters (8). Wiring according to claim 1, characterized in that the limiting circuits consist of a series combination of Zener diode (8) and back-up diodes (7).