How much is the instantaneous current of a 90kw motor soft start?

1. Introduction

As an indispensable power equipment in industrial production, the starting method of the motor has an important impact on the motor's service life, energy consumption, and mechanical impact during the starting process. Although the traditional direct starting method is simple, the starting current is large, which has a certain impact on the power grid and the motor itself. As a new motor starting method, soft starting technology can effectively reduce the starting current, reduce the mechanical impact during the starting process, and improve the motor's service life and operating efficiency.

2. The principle of soft start technology

1. Soft Start Technology Overview

软启动技术是指在电机启动过程中，通过控制电机的输入电压或电流，使电机从零速逐渐加速到额定转速的一种启动方式。与传统的直接启动相比，软启动技术可以显著降低启动电流，减少启动过程中的机械冲击，提高电机的使用寿命和运行效率。

1. The principle of soft start technology

The principle of soft start technology is to control the input voltage or current of the motor so that the torque and current of the motor gradually increase during the starting process, thereby achieving smooth starting. Specifically, soft start technology can be divided into the following types:

(1) Voltage-controlled soft start: By controlling the input voltage of the motor, the voltage of the motor gradually increases during the starting process, thereby achieving smooth starting.

(2) Current-controlled soft start: By controlling the input current of the motor, the current of the motor gradually increases during the starting process, thereby achieving smooth starting.

(3) Torque-controlled soft start: By controlling the input torque of the motor, the torque of the motor gradually increases during the starting process, thereby achieving smooth starting.

3. Analysis of transient current of 90kW motor soft start

1. 90kW motor basic parameters

Before analyzing the instantaneous current of a 90kW motor soft start, we first need to understand the basic parameters of the motor, including rated power, rated voltage, rated current, rated speed, etc. Taking a common three-phase asynchronous motor as an example, its basic parameters are as follows:

• Rated power: 90kW

• Rated voltage: 380V

• Rated current: 160A

• Rated speed: 1460r/min

1. Soft start instantaneous current calculation

During the soft start process, the input voltage or current of the motor will gradually increase, so the instantaneous current will also change accordingly. According to the starting characteristics of the motor and the principle of soft start technology, the instantaneous current of a 90kW motor during the soft start process can be calculated.

(1) Calculation of instantaneous current of voltage-controlled soft start

Assuming that the input voltage of the motor gradually increases from 0 to the rated voltage during the starting process, the following formula can be obtained based on the starting characteristics of the motor:

I(t) = Ie * (V(t) / Ve)^2

Among them, I(t) is the current of the motor at time t, Ie is the rated current of the motor, V(t) is the input voltage of the motor at time t, and Ve is the rated voltage of the motor.

(2) Calculation of instantaneous current of current-controlled soft start

Assuming that the input current of the motor gradually increases from 0 to the rated current during the starting process, the following formula can be obtained based on the starting characteristics of the motor:

I(t) = Ie * (t / T)^k

Among them, I(t) is the current of the motor at time t, Ie is the rated current of the motor, T is the total time of the soft start process, and k is the exponent of current increase.

1. Factors affecting soft start instantaneous current

In practical applications, the magnitude of the instantaneous current of a 90kW motor soft start is affected by many factors, including:

(1) Motor parameters: The motor's rated power, rated voltage, rated current and other parameters will affect the instantaneous current during the soft start process.

(2) Soft start mode: Different soft start modes (such as voltage control, current control, and torque control) will affect the changing pattern of instantaneous current.

(3) Starting conditions: The load, ambient temperature, power supply voltage and other conditions during the starting process will also affect the magnitude of the instantaneous current.

4. Application of soft start technology in 90kW motor starting

1. Advantages of Soft Start Technology

(1) Reduce starting current: Soft start technology can effectively reduce the current during motor starting and reduce the impact on the power grid and motor.

(2) Reduce mechanical shock: Smooth acceleration during soft start can reduce the mechanical shock during motor start-up and extend the service life of the motor.

(3) Improve starting efficiency: Soft start technology can improve the efficiency of the motor starting process and reduce energy consumption.

1. Application areas of soft start technology

Soft start technology is widely used in various industrial fields, such as chemical, steel, cement, mining, etc., and is especially suitable for motors with high power and high starting current.