Electric drives of inclined conveyers - heading

Contents

1. Task

2. Introduction

3. Power calculation and engine type selection

4. Calculation of starting and adjustment resistances of electric drives

5. Calculation of transient processes of electric drives

6. Check of selected engine by heating

7. Description of operation of electrical circuit diagram

8. Specification

9. List of literature

Description of operation of electrical circuit diagram

No power is supplied to the circuit at the start time. The QF circuit breaker is switched on. Gets power to the control circuit. At that KL coil is de-energized. Its contacts in a power chain are opened, and in chains of RU1 and KT - are closed. Contactors 1U, 2U, 3U without voltage and their power contacts are open, and contacts in the control circuit are closed. Relays of acceleration of RU1 are RU3 on tension and their contacts in the control circuit are opened. Since the engine is standing and its speed is equal to 0 contact of PCC is opened.

To start the engine press "Start" button of CP. In this case, the CL contactor receives power and becomes self-energized, which allows not to keep the "Start" button constantly. HF contacts in the power circuit are closed and the engine is powered. TC contact in RU1 circuit is opened and RU1 coil is de-energized. At the same time with endurance of time the contact of RU1 becomes isolated and tension on the contactor 1U moves. Its power contact in the rotor circuit closes, shunting the 1st resistance stage. Pin 1U in the control circuit opens and removes power from the acceleration relay RU2. With endurance of time the contact of RU2 in a chain 2U becomes isolated. Since 2U receives power, its power contact in the rotor circuit closes, shunting the 2nd resistance stage. Contact 2U opens and voltage is removed from contactor RU3. Contact RU3 will close with time delay. 3U receives power supply and its power contact in the rotor circuit shunts the 3rd resistance stage. The engine will come to a natural characteristic .

To brake the conveyor press "Stop" button of CS. At that, KL coil is de-energized and power contacts open. TC contacts in control circuit close. Since the engine speed is high, the PCC contact is closed and the CT contactor will be energized. The CT contacts in the power circuit are closed and the engine will remain energized. After closing of CL contact in RU1 circuit open contacts RU1 - RU3 in series, which will fully introduce resistance into rotor circuit. Since the CT dynamic braking contactor was switched on, direct current is supplied to the stator winding through the step-down transformer T, the rectifier semiconductor bridge and the closed contacts of the CT, as a result of which dynamic braking is carried out. When the engine speed is close to 0, the PCC contact opens and the engine is de-energized .

After the dynamic braking is over and the PCC contact opens, the CT contactor will remain without voltage and its contacts in the TM circuit are closed. Thus, braking with a mechanical brake lining will be carried out.

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