CS240522B1 - Wiring for automatic tripping of DC motors with thyristor rectifier - Google Patents

Abstract

The solution concerns DC motors with a thyristor rectifier. The switching contact of the switching relay is connected to the input of the excitation current regulator, and the contact of the time relay is connected in series to the parallel-connected second switching contacts of the first to n-th relays of technological applications, while the parallel-connected windings of the switching relay and the time relay are connected in series to the parallel-connected first switching contacts of the first, second to n-th relays of technological applications.

Description

The invention relates to a circuit for automatic switching off of the excitation current of DC motors with a thyristor rectifier.

In the known rectifiers, the excitation of the DC motor is switched on at the same time as the rectifier is switched on. This method is energy-disadvantageous because unnecessary heat losses occur in the excitation circuit, although the self-propelled drive is not yet operating.

The above drawbacks are eliminated by a circuit for automatic tripping of the excitation current of DC thyristor rectifier motors according to the invention, wherein the switching relay contact is connected at the input of the excitation current controller and connected in series by the second switching contacts of the first to nth technology request relays . a timing relay contact, wherein parallel wired switching relay and timing relay windings are connected in series to the parallel connected first switching contacts of the first to nth technology request relays.

The circuit according to the invention avoids heat loss if the actuator itself does not operate and at the same time the service life of the excitation motor winding is increased.

In the accompanying drawing, a circuit diagram according to the invention is shown in principle.

The excitation current setpoint P is supplied from the potentiometer P to the input of the excitation current regulator Rib. The output of the excitation current regulator Rib is fed to the generator Gzi of the ignition pulses that control the thyristor rectifier. At the speed controller input Rw, a speed reference value ω is applied via contacts 1bi to 1b _{n of the} first to n-th relays Bj, B ₂ to B _{n of} the speed controller and the actual speed value ω from the tachogenerator TG. The actual speed value ω is still connected to the input, the zero speed evaluation circuit, whose output switches the relay K _{in by} its contacts lk _{! N} at non-zero speed.

At the input of the field current setpoint, the field current regulator Rib, a normally open contact Ik of a switching relay is connected. The second normally open contacts 2k _lt 2k ₂ to 2k _{n of the} first to nth relay K _b K ₂ to K _{n of} technological requests are connected in series by the contact 1k of the time relay K _n . Parallel connected first make contacts lk _b lk ₂ to lk _{n of the} first to nth relay K _lt K ₂ to K _{n of} technological requests and make contact lk _n , relay Κ _ιπ are connected in series with a parallel combination of switch relay K _£ and time relay K _fI . An armature ignition generator Gzik is connected to the speed regulator Rw via the armature current regulator Rik.

When no-switched technological applications and zero actual speed of the drive is not turned on any relay and the energizing current switching relay contacts LKI to _£ disconnected from the regulator Rib excitation current. When one of the technology requests is switched on, one of the technology request relays K _b K ₂ to K _n switches the switching relay Kq and switches the field current setpoint ib to potentiometer P and the current starts to pass through the field winding circuit. After the set time has elapsed, the timer relay K 'switches on and unlocks the technology request for the armature current regulator ¹ Rik by its contacts 1k _H. Delays in the armature controller Rik request are required so that the motor armature flows current until the nominal excitation current is reached.

The circuit for the automatic tripping of the field current according to the invention can be used in drives with a DC motor with a thyristor rectifier, e.g. for driving traction stools for production of drawn material.

Claims (1)

OBJECT OF THE INVENTION A circuit for automatically tripping a DC motor with a thyristor rectifier, wherein the winding of the first, second to n-th regulator relays is serially connected to the second contacts of the first, second to n-th speed controller relays are connected to the input of a speed controller, characterized in that a switching contact (lki j of the switching relay (K i) and a second switching contact (2k 2k 2 to 2 k) of the first to n th relay (K1 (K2 to Kn) connected to the second switching contact (2kb 2k2 to 2k) connected in parallel to the exciter current controller ] of the technology requests, a time relay contact (1k) is connected in series, whereby the first switching contacts (1k1; 1k2 to 1k) of the first, second to nth relay (Kb K2 to Kn) of the technological requests are connected in series Switch relay coil wiring (¾) in parallel and time relay {Kuj.