SU78404A1 - Device for automatically starting the DC motor - Google Patents

Description

The subject of the invention is a device for automatically starting DC motors based on the use of balanced (differential) acceleration relays, whose holding coils are connected in parallel to the starting resistance sections and respond to the magnitude of the load current of the motor.

A special feature of the proposed device is the inclusion of the working of the balance relay relays parallel to the motor pole, which ensures automatic start-up depending not only on the current, but also on the speed of the engine.

The device layout possesses simplicity, reliability, is adapted to significant fluctuations in the power supply network april and does not require the use of complex, heavy or cumbersome devices.

The drawing shows a circuit diagram of the device.

A schematic of the engine shunt excitation device is described below. However, the circuit can be successfully applied to engines with any excitation system.

32 Code Release 1. h., 1950 i.

The working coil of each balance relay is connected in parallel to the motor core and, thus, measures the back-EMF, then as the holding coil is turned on in parallel with the starting resistances and thereby measures the current of the core.

When the start button is pressed, two linear contactors // G / 7 and 2 CL are turned on, one of which blocks the button with its blocking contact. The main contacts of the linear contactors connect the motor to the network through the starting resistance R. At the first moment, the back-EMF is zero, and the voltage drop in the resistance is equal to the network voltage. The acceleration relays cannot work, since there is no voltage on the working coils. As the engine accelerates, the tendency of the Has working coil, equal to counter-emf, increases, and the voltage on the holding coil, proportional to the current of the core, decreases.

At a certain ratio m, intern): by these voltages, the 1RU relay will turn on the 1KU contactor, which will ground the first start resistance.

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After that, the engine will continue to accelerate and with some greater ratio between the prote-EMF and the voltage and starting resistance, the relay 2RU and the contactor 2KU, etc. will operate (The diagram shows two levels of starting resistance, but there may be more).

The complete starter circuit usually includes, in addition, hardware protection and alarms. Sometimes the circuit can be complicated, if you want, for example, to disconnect the 1KU contactor and the acceleration relay after the end of the loop, or, if small-sized "contactors are required, which do not have to be switched on (resistance). are principled.

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Subject invention

A device for automatic starting of a DC motor, a state of starting contactors and several acceleration relays, made in the form of balanced relays, holding coils of which are connected in parallel to the starting resistance sections and react to the magnitude of the load current of the engine, characterized in that The purpose of the automatic start-up, depending not only on the current, but also on the engine speed, the working coils of the balanced relays are connected in parallel to the switch and react to its EMF (speed of the riflee, eni).

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