Mainly to detect the phase angle between the leading voltage and current at a time zeropoint, and leading phase the cosine of this angle is so called the power factor.
‧ The gate of the system closes when the current passes the zero point, meaning there is no more current output to the motor.
‧ According to the size of the load, the microcomputer will decide at what time to open the gate and output to the motor again (dynamic control).
‧ The lower the load, the longer the gate stays closed and the larger the energy-saving efficiency.
‧ The microcomputer control system continues to detect load status and continues to control electric output to motor (dynamic control).
‧ In a way, the system is similar to a dam; when there is need for more water, the gate will open more (dynamic control).
‧ The energy-saving capabilities of this system increasewith deceasing load size and decrease forincreasing loads.
‧ The system changes the energy-saving rate according to changes in load.
‧ System will not stop the motor due to sudden increases in load.
‧ The system’s tracing and following capabilities perform in a very smooth manner.
Special Features and Applications
1. Soft start feature
Usually when the motor starts at full force, the starting current surpassesfrom 6 to 9 times over the rated current. The system uses a microcomputer smart dynamic control, which can control starting current to be under 2 times the rated current. The system can make the starting current to gradually increase to a rated current level until achieving motor start.
2. Kick-start feature
For motors with greater inertia, the soft start might not be able to provide enough torque to start the motor. A relatively higher voltage can produce enough torque to start the motor. After kick-start, the system changes back to soft start and continues to start the motor.
3. Soft stop feature
Some motors need a soft stop to avoid sudden impulses during stopping operation, and in the case of water pump motor, it can avoid water hammer and valve damage due to sudden motor stop.
4. Phase loss protection feature
When phase loss occurs, system will automatically stop output to motor, avoiding anydamage to it.
5. Overload protection feature
When overload occurs, the system will automatically stop output to motor, effectively protecting it.
6. High voltage overload protection feature
When there is voltage overload, the system will stop output to motor. This protects the system and the motor. According to the real-time needs, the system will determine toautomatically re-start or not the motor when voltage returns to a normal range.
7. Undervoltage protection feature
If voltage is too low, the system can be set to:
a. Automatically switch to full voltage, non-energy saving mode to avoid undervoltage in energy saving mode.
b. Stop the motor.
c. When voltage returns to a normal range, re-start the motor.
External bypass feature
When needed, the system can connect to an external bypass system.
Automatic external bypass function
If the system is performing only as soft starter, the system can be set to connect automatically to an external bypass system after soft start; the system will stop operation, increasing its service life.
9. Special applications for compressors
To avoid high starting currents in larger compressors, usually the motor will not stop duringunloading. The system can be set to stop the motor automatically when the compressor unloads, and automatically restart the motor when in need to provide load; this way we can achieve 100% energy saving during unload.
10. Special applications for water pumps
Besides soft start and soft stop features for water pumps, when encountering voltage overload or undervoltage, the system can be set to automatically stop the motor; when voltage returns to a normal range, the motor can automatically re-start by soft start.
Special characteristics:
1. Non-contact programmable voltage-drop start, soft start, soft stop, programmable voltage-drop start, effectively improving the effect of the machine start-up on the electrical network, also decreasing the originally high mechanical impact that the machine received during start-up, automatically increasing the starting voltage according to faster machine start-up speed. The benefits of machine starting performance are evident in start-up load for fans and pumps carrying loads. When compared to γ-▲starters and self-coupling voltage-drop starters, the biggest advantages are suitable frequency start, suitable load start, smooth start speed-up, no noise, no vibration, no spark, and a wide range of applicability.
2. Uses energy saving control software to achieve energy saving. The adaptive control automatically adjusts the machine’s input voltage according to changes in loading rate in the machine, increasing the power factor during machine operation. At the same time, reducing the machine’s power waste during operation. For machines with normally low loads, or with very large load changes, the energy-saving efficiency is more evident.
3. Energy saving can also apply to partial loads. While operating loads under 60%, the energy-saving average is 15%; if the system is operated under this condition for an extended period of time, the installation costs can be recovered in 2~3 years.
4. Full-featured protection system. The machine control system encompasses soft start, kick-start, soft stop, phase loss protection, overload protection, voltage overload protection, undervoltage protection and external bypass features.
5. Uses the most recent microcomputer digital control technology, system has the most diverse and simplistic control circuit integration. We have increased the reliability of system operation, reducing the need for maintenance. At the same time, reducing the likelihood of stopping the transmission system, increasing overall production efficiency. Because of the non-contact feature, the system eliminates the effects of faulty contacts. Reliable operation, a strong resistance to interference, convenient maintenance, and expected service life of over 10 years.
Summary of applied technologies:
1. Why can we save energy in electric motor assemblies?
From the birth of electric motors until now, it is common for all types of electric motors todevelop energy surplus, meaning there is a serious waste of electricity; the reasons behind these phenomena might be one or more of the following:
1. The capacity of the installed electric motor is too big:
Because the biggest consideration regarding load is equipment capacity, the carried load during normal operation is small, and incidentally the equipmentwill perform only when carrying larger loads. For inertial loads, the load is larger at machine start-up, and the load decreases during normal operation of the machine, if the load is large but there is no large capacity machine to accompany it,the system will not perform.
2. Light loading operationover an extended period of time:
Production equipment spends most part of their time in preparation, such as waiting for preparation of materials. If the load is light, if equipment is normally on, if stopping the machine will result in damage or if it is not appropriate to stop the machine, or even some machines cannot be stopped at all, so there is only a small fraction of time when the machine performs under a heavy load.
3. Irregular load operation over an extended period of time:
There are possibilities of large irregular load changesin equipment intended for operation at public spaces, commercial buildings or similar businesses (such as escalators, air conditioning, refrigeration equipment, etc.), and therefore smaller capacity machines cannot meet the desired needs when there are too many users or loads are too heavy. Therefore,machines with larger capacities are needed, with a large tolerance as precaution for any future overloads.
4. Regular dynamic load operation over an extended period of time:
There are some machines that when between an unloaded state and a heavy load, or under a light load and a heavy load will display performance with systematic changes. Some machines will move due to free-fall or inertia of the heavy load during operation, soduring all-year operation,there will be apart where electrical energy is not used adequately, and electricity is wasted unknowingly.
5. Unusually high supply voltage creates waste:
To avoid circuitry damage during power transmissionortoo low terminal voltage due to electrical spikes, output voltage is always very high in electricity supply systems. The supplied voltage often surpasses the rated voltage; the machine’s magnetic flux or flux density increase with increasing voltage, iron and copper damage increase, and finally induces temperature increase in the machine, reducing service life and increasing energy waste.
2. Working Principles
Equipment voltage is reduced under light loading conditions, air gap flux and damage to copper winding is reduced, increasing the capabilities and energy-saving efficiency of load equipment. For dynamic production equipment under normal conditions over an extended period of time, light loads occurs more often than a full loads;using microcomputer chip control technology we can detect detailed operating conditions of the machine, synchronously trace the actual needs of the machine during production and adjust automatically, so the machine will work more efficiently and smoothly.
By using smart microprocessor control systems, we can completely automatize or semi-automatize the tracing and detection of load changes during normal machine operation. The detected signal goes through a specialized channel to the tracing software system, it is analyzed, and then the voltage and current needed for operation are dynamically adjusted, under the premise that the machine’s RPM will not change;precise compatibility of the output torque and load is kept; there is effective reduction of damage by active and reactive power; there is reduction of magnetic damage; while at the same time, increasing the machine’s power factor. Under a light loading, the voltage of machine will be automatically regulated to the lowest requirement, and the RPM is kept constant, reducing the machine’s determinant field current, evidently reducingdamage to supply circuitry, damage to the machine’s copper coils, and damage to the machine’s iron, avoiding waste of electrical energy by the machine, increasing machine efficiency. If the load increases, voltage can automatically increase after passing through the a SCRto avoid slowing down the machine,matching the output power and immediate loading of the machine, thereby reducing the damage to copper and iron, improving the starting performance of the machine, and achieving ourgoal of energy efficiency. At the same time, a continuously smooth start of the machine is guaranteed, eliminating mechanical impact created by high starting current from all the other conventional methods, effectively reducing any damage to axles and belts, greatly reducing the mechanical stress at the transmission mechanism, thereby increasing service life of equipment.
3. Suitable Applications
Suitable for electromechanical machines with inertial loadings that experience low loading rate, changes in load, low power factor.
4. The relationship between power factor and loading rate
When electric generators drag on conventional mechanical equipment, the loading in the equipment becomes lighter (loading rate in generator becomes lower), the power factor of the electric generator also becomes smaller. After installation of this kind of equipment, it is possible to effectively increase the power factor of the system.
5. What are the operating characteristics of inertial loadings
Mechanical equipment that drags conventional electric generators have a certain definite inertia due to their own weight;the bigger the weight of the mechanical equipment, the larger the inertia. When designing inertial equipment,the start-up characteristics and mechanical characteristics have been considered, and usually we will choose higher power electric generators to perform dragging, and only a small maintained torque is needed for operation after the equipment has started; at this time the load in the electric generator will be very low, so most of the time there will be energy surplus.
6. Relationship between loading rate and economization rate
The smaller the loading in the machine, the higher the energy surplus, therefore, the space for energy saving is larger, and economization rate is also larger.
7. The effect of voltage on economization rate
The larger the supplied voltage compared to the normal voltage, the higher the damage to the machine; at this time the energy saving space is larger and the achievable economization rate is also higher.
8. Factors that affect economization rate
Machine loading rate, supplied voltage, speed at which change in loading rate occurs, machine’s power factor, etc.
9. What is soft start
During start-up, machines usually need a large surge current (normally 6 to 8 times higher than Ie);the mechanical stress is also higher due to start-up, which decreases the service life of the equipment. In the past, many have used methods such as γ/▲transform, auto-coupling voltage reduction, voltage reduction by magnetic control, etc. to achieve this. Although these methods can operate up to a definitelimiting current, in the case of a variable voltage, the impact problem due to current still remains to be solved. Following the rapid development of electric and electronic technologies, the soft starter can achieve a very smooth machine start-up and no mechanical impact during start-up process, and can adjust the start-up parameters according to the characteristics of the machine’s loading, such as limiting current value, start-up time, etc. Moreover, there are many other protection features for the machine, which arise from the problems commonly encountered in voltage-reduction equipment.
10. Characteristics of soft start
1. Restricts starting current, avoiding instantaneous voltage drop by supply circuitry during start-up.
2. Reduces the capacity of power supply equipment, investment in newly built energy-saving project.
3. To avoid torque impact during start-up, it reduces the stress applied to the gearbox and the transmission belt, eliminating the bending and breaking of the electric axle and transmission axle, increasing service life.
4. It can solve the problem of water pressure fluctuation in water pumps during start-up and stop, effectively avoiding water hammer effect. Also avoids water pressure impact on the pumping medium and cracking of tubes during start-up and stop.
5. It can avoid harm to completed products in conveyor belts, weight lifting equipment, weaving machines, etc. due to sudden start or stop of the system.
6. The machine can be started more frequently, protecting the machine against over-heating or burnout.
7. The automatic switch of the machine’s power supply can be delayed and therefore service life of contacts extended, increasing equipment reliability and reducing equipment maintenance cost.
8. High torque, soft start can be achieved in some specific machines
9. The equipment’s external connections and auto-coupling voltage-reduction starter are the same, but substantially increases the protection features for the machine.
11. Does it affect equipment speed?
The rpm of electric generator derives from the frequency of the power supply, and the microcomputer relies on adjusting the power supply voltage to control energy efficiency; the microcomputer control system dynamically controls the voltage, which does not changes the equipment performance or speed.
|
