CN200994113Y - Large-sized motor liquid-state reduced-voltage reactive compensating soft starting device - Google Patents

Abstract

The name of the utility model is a large-scale motor liquid step-down reactive power compensation soft start device, which belongs to the field of electric technology and relates to a large-scale motor step-down soft start device. It solves the disadvantages of low starting power factor and large high-order harmonic components of the existing large-scale motors using reactors; the driving device of the transformer motor unit requires a large enough capacity of the public power grid; The utility model includes a liquid step-down soft starter and a switch for starting and running. The inlet end of the liquid step-down soft starter is connected to the power grid through a switch in a starter cabinet, and the outlet end is connected to a motor through a switch in a switch cabinet. There is also a reactive power compensation capacitor connected in parallel with the outlet terminal of the starting device. The utility model can reduce the starting current of the motor and the influence of the starting of the motor on the grid voltage, reduce the voltage fluctuation range, improve the power factor when the motor starts, and has the advantages of simple structure, reliable performance, low cost and convenient use and maintenance.

Description

Liquid step-down reactive power compensation soft start device for large electric motors

technical field

The utility model belongs to the technical field of electric engineering, in particular to a main circuit of a step-down soft starter for a large motor.

Background technique

At present, the starting of large-capacity AC induction motors requires step-down starting to reduce the impact on the power grid when starting the motor. Now, the device for step-down starting of large-scale motors has a magnetically controlled soft starter, that is, starting with a reactor and starting with a step-down transformer. device and high-voltage frequency conversion soft starter, in which the magnetic control soft starter has a low power factor and a large high-order harmonic component when starting; the transformer step-down starting device requires that the public power grid is large enough, or the short-circuit capacity of the open contact is large enough; the high-voltage frequency conversion Although the soft starter has a good starting effect, the cost is high, and the high cost of use and maintenance is not convenient for widespread application.

Contents of the invention

The purpose of this utility model is to overcome the deficiencies existing in the existing soft starter device, to provide a device that can reduce the starting current of a high-voltage large-scale motor, reduce the impact on the public grid voltage, and has a simple structure, reliable performance, low cost, easy to use and maintain A convenient liquid step-down reactive power compensation soft start device for large electric motors.

The technical scheme of the utility model is: the utility model includes a liquid step-down soft starter A and a switch cabinet for starting and running. The switching cabinet switch 3QF is connected with the motor M, and the characteristic is that the outlet terminal of the starting device is also connected with a reactive power compensation capacitor C in parallel.

The reactive power compensation capacitor C mentioned in the technical solution of the utility model includes reactive power compensation capacitors C ₁ and C ₂ .

Said reactive compensation capacitor _C1 in the technical solution of the utility model is connected in parallel with the motor M, and the compensation capacitor _C2 is connected in parallel with the running switch 4QF series circuit and the motor M.

The utility model has the advantages: 1. Reduce the starting current of the motor; 2. Reduce the impact on the grid voltage when the motor starts, and reduce the fluctuation range of the grid voltage when starting; 3. Improve the power factor when the motor starts; 4. Simple structure and reliable performance , low cost, easy to use and maintain.

Description of drawings

Fig. 1, Fig. 2 are two kinds of typical example one-line diagrams of the present utility model;

Below in conjunction with accompanying drawing and example the utility model is described in further detail.

Detailed ways

In the example shown in Figure 1, A is a liquid step-down soft starter, B is a power transformer, C ₁ and C ₂ are reactive power compensation capacitors, 1QF is a motor running switch, 2QF, 3QF, and 4QF are motor M start switches respectively. The inlet end of the liquid step-down soft starter A is connected to the power transformer B through the switch 2QF, the outlet end is connected to the motor M through the 3QF, the capacitor bank C ₂ is connected in parallel with the motor M, and the outlet end of the step-down soft starter A is connected in parallel through the 4QF Connected with capacitor bank C ₁ , C ₁ and C ₂ compensate the reactive power of the starting circuit when starting. When the running switch 1QF of the motor M is turned off before starting, the switches 3QF and 4QF of the starting circuit are closed, and the motor M is in the state of waiting to start. , or when the starting circuit current begins to drop, disconnect 4QF and cut off balancing capacitor C ₁ , after a few seconds delay 1QF closes, and at the same time 2QF and 3QF disconnect, capacitor C ₂ continues to run in parallel with the motor, capacitors C ₁ , The total capacity of _C2 is determined according to the extent of the electric motor starting inrush current that the power system can withstand, and the capacity of the compensation capacitor _C2 is determined according to the need for reactive power compensation when the motor is running.

In the example in Fig. 2, except that the running reactive power compensation capacitor C ₂ is cancelled, the others are the same as the example in Fig. 1 .

Claims (3)

1, a kind of liquid-state step-down reactive compensation soft starter for high-capacity motor device, comprise liquid-state step-down soft starter device A and starting and operation diverter switch cabinet, electrical network is inserted by starting cabinet switch 2QF in the end of incoming cables of liquid-state step-down soft starter device, leading-out terminal links to each other with motor M by switching cabinet switch 3QF, it is characterized in that the starting device leading-out terminal also and be connected to the reactive power compensation capacitor C.

2, liquid-state step-down reactive compensation soft starter for high-capacity motor device according to claim 1 is characterized in that said reactive power compensation capacitor C comprises reactive-load compensation capacitor C ₁And C ₂

3, liquid-state step-down reactive compensation soft starter for high-capacity motor device according to claim 1 and 2 is characterized in that said reactive-load compensation capacitor C ₁With motor M parallel connection, run switch 4QF and reactive-load compensation capacitor C ₂Series circuit is in parallel with motor M.

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