Equipment: 75KW AC asynchronous motor, controlled by inverter.
Nature of work: According to the factory's full-load 24-hour work system, 300 days of work throughout the year.
Operating conditions: throttle fan
According to the characteristics and nature of the fan's work, inverters are used to save energy and save energy in the following aspects:
1. Due to the use of frequency converter to change the air volume, it is more energy-saving than the damper to adjust the air volume.
Fundamental
The air volume is proportional to the motor speed,
The wind pressure is proportional to the square of the motor speed
Motor input power is proportional to motor speed cube
Such as: usually 80% throttle opening, the use of inverter to change the air volume does not use throttle energy,
When the throttle opening is 80%
Motor input power P gate = =0.9Pe
Change 80% air volume after changing air volume with frequency converter
Motor input power from the grid P frequency = = 0.512Pe
Energy saving
ΔP = P gate - P frequency conversion
=0.9Pe-0.512Pe
=0.388Pe
=0.388×75KW
=29.1KW
Annual savings ΔP*24*300=29.1KW*24H*300=209520KW·H
Annual savings in operating electricity costs 209520KW·H*0.6=125712
2 Before the transformation, the fan starts directly. The 300A range meter head shows full deflection. The motor current is 120A. It is estimated from 4 to 6 times of the rated current. The starting current is calculated as 4Ie or 480A. The actual starting current of the inverter is 1.2Ie, that is, 1.2Ie= 144A.
The total motor starting current is 1 × 4 × Ie = 480A;
The total starting current of the inverter is: 1×1.2×Ie=144A;
Motor voltage 380V
According to the start once a day, the start time of the transformer is 60s, and the hydraulic coupler is 30s;
The total power consumption of fan motor starting is: 2.6 kW·h;
The total daily power consumption of the inverter is: 1.5kW·h;
Start to save power: 2.6-1.5=0.9kW·h;
Start to save electricity costs: 0.9 × 0.6 = 0.45 yuan;
Annual electricity savings: 300 days x 0.45 yuan = 13.5 yuan.
In the selection of transmission gears and belts, the quality of the objects to be transported should be taken into consideration. The friction factor should be selected as small as possible, but the speed and the acceleration of the heavy objects can be satisfied, so that the objects produce as little frictional heat as possible in the belt. This depends on the specific conditions. Calculation and analysis.
In short, the inverter is used for 50Hz speed control. No matter whether it is a square torque characteristic load or a constant torque characteristic load, the speed regulation can fully achieve the energy saving effect, and the non-speed regulation operating under the power frequency is the effect of energy saving 1, 2 and both. Sometimes the power factor of the system is very low. After the frequency converter is used, there are also energy-saving effects. This is not energy-saving in the frequency conversion speed control, but the energy saving brought by the compensation power factor. And the inverter is small in size, large in power and heat capacity, good in thermal stability in operation, wide in frequency modulation range, high in resolution, complete in protection and high in sensitivity. The main power device has good self-protection function, balanced operation, and complete communication interface. Host computer and remote control; due to the power automatic balance function, the vibration of the original rotating system is eliminated.
The total calculation:
Other wind energy saving: 209520KW·H Economic benefits: 125,712 ten thousand yuan
The total economic benefits totaled 126,000 yuan, but it does not include belts, gears, etc., because of the use of a frequency converter to start up, and the operation has been smoothly reduced.
The conservative calculation of the fan with the 75KW AC asynchronous motor is more than 200,000 yuan. Other power can be calculated in the same way.