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How does inverter save energy?

2021-01-07
How does inverter save energy?
1. Control the starting current of the motor
When the motor is directly started through the power frequency, it will produce 7 ~ 8
times of the rated current of the motor, which will greatly increase the electrical
stress of the motor winding and generate heat, thus reducing the life of the motor. The
frequency converter speed regulation can be used under the condition of zero speed and
zero voltage. Once the relationship between frequency and voltage is established, the
frequency converter can drive the load to work according to V / f or vector control. The
use of frequency converter speed regulation can fully reduce the starting current and
improve the bearing capacity of the winding. The direct benefit to the heating
enterprises is that the maintenance cost of the motor is further reduced and the service
life of the motor is increased.
2. Reduce the voltage fluctuation of power lines and improve the quality of power grid
When the motor starts at power frequency, the current will increase sharply, and the
voltage will fluctuate greatly. The range of voltage drop will depend on the power of
starting motor and the capacity of distribution network. Voltage drop will lead to fault
trip or abnormal operation of voltage sensitive equipment in the same power supply
network, such as DCS system, PC and contactor. After adopting frequency conversion speed
regulation, starting gradually at zero frequency and zero voltage, the voltage drop can
be eliminated to the greatest extent.
3. Lower power is required when starting
The motor power is proportional to the product of current and voltage. The power
consumed by the motor directly started by the working device will be much higher than
the power required by the inverter. The direct start of 315KW circulating pump will have
a serious impact on other equipment, even make the transformer over-current trip, so as
to be warned by the power sector. The inverter is used for power supply If the engine
is started or stopped, similar problems will not occur.
4. Adjustable acceleration and deceleration function
Speed and torque limit inverter speed control can be set according to the needs of users
freely acceleration and deceleration time, its acceleration and deceleration mode can
also be selected, such as, linear, S-type, etc. In this way, the motor or the connected
mechanical part of the shaft or gear will not produce severe vibration, further reducing
the mechanical wear and loss. At the same time, it can easily and smoothly adjust the
running speed by adding potentiometer or manual operator. After speed regulation by
frequency converter, it can set the corresponding torque limit to protect the machinery
from damage, so as to ensure the continuity of the production process and the
reliability of the product. The current frequency conversion technology makes the torque
limit adjustable, and even the torque control accuracy can reach about 3% ~ 5%.
5. Variable frequency speed regulation is used for pump water pipeline
In the heating enterprises, the utilization rate of water pump is the highest, and the
water hammer effect is the most prominent and the most important problem to be solved.
When the electric water pump starts under the full pressure, the starting time is less
than 1 second. In less than 1 second, the flow of the pipeline increases from zero to
rated flow. The very sharp change of fluid flow will produce the impact force of too
high or too low pressure in the pipeline, and the phenomenon of / cavitation 0 effect
may appear.
The pressure impact on the pipe wall will produce noise, just like the hammer hitting
the pipe, which is called / water hammer effect 0. Water hammer effect not only produces
noise, but also causes physical damage. At the moment when the pressure is too high,
the pipe may break. When the pressure is too low, the tube will collapse. The cavitation
effect will cause the strong agitation of the liquid, which will lead to the erosion of
the inner wall of the pipe and the vaporization of the liquid. In addition, the water
hammer effect may also damage the valves and fasteners. In case of direct shutdown, the
potential energy of the liquid will overcome the inertia of the motor and make the
system stop sharply, which will also cause pressure impact and water hammer effect.
After adopting frequency conversion speed regulation, the rise and fall time can be set
according to the needs, so that the flow rate change rate in the pipeline system can be
reduced to the allowable range, so as to completely eliminate the water hammer effect.
Not only the method is very simple, but also the effect is the most ideal.