Home » Blog » VFD industry » Variable speed drive in pump control characteristics
Variable speed drive in pump control characteristics
Electric motor restart
Some pumps require high efficiency operation, which usually need power frequency supply and variable frequency power supply switching at any time. For example, a residential area using deep geothermal water for heating, with three motors - water pump heating is controlled by a variable speed drive, the maximum frequency is 50Hz, the largest water supply volume is two motor units operation in power frequency supply. According to diurnal temperature changes with different demands for heating, the system's two motor units can be: one motor running in power frequency, the other one running in variable frequency (50Hz less) power; one motor outage, the other one running in variable frequency power. The third motor is controlled by soft starter to make mutual backup with other two motors. Therefore, such operation methods not only meet the heating requirements, improve operational efficiency, but also save lots of electricity energies. However, in those operation methods, it requires the variable frequency drive has speed tracking feature, particularly from the commercial power supply switches to variable frequency operation. Thus, the motor has a smooth switching when power supply cut off, from idle to restart, thereby enhance the system reliability and stability in continuous operation.
Self-diagnosis of continuous operation
Due to power disturbances, the pumps often tripped and the reasons are difficult to find out. When an abnormal condition occurs, the variable speed drive can perform self-diagnosis first, if the system has no problem it will reset and restart automatically, and find out the electric motor deceleration reasons in self-diagnosis by speed detection function during this period, and make it reaches the original speed, which requires the system should be integrated abnormal shutdown recovery function.
Free tripping operation function
Pump driving has torque decreased characteristic, effective overload protection function is important to make it running on the over-torque conditions. In this case, once the overload current reaches the set value, reduce the variable speed drive output frequency, that is stall in running. For such torque decreased loads, the variable speed drive can be running at the balance point for a short time, and restore original set frequency automatically after the load drops.
Some pumps require high efficiency operation, which usually need power frequency supply and variable frequency power supply switching at any time. For example, a residential area using deep geothermal water for heating, with three motors - water pump heating is controlled by a variable speed drive, the maximum frequency is 50Hz, the largest water supply volume is two motor units operation in power frequency supply. According to diurnal temperature changes with different demands for heating, the system's two motor units can be: one motor running in power frequency, the other one running in variable frequency (50Hz less) power; one motor outage, the other one running in variable frequency power. The third motor is controlled by soft starter to make mutual backup with other two motors. Therefore, such operation methods not only meet the heating requirements, improve operational efficiency, but also save lots of electricity energies. However, in those operation methods, it requires the variable frequency drive has speed tracking feature, particularly from the commercial power supply switches to variable frequency operation. Thus, the motor has a smooth switching when power supply cut off, from idle to restart, thereby enhance the system reliability and stability in continuous operation.
Self-diagnosis of continuous operation
Due to power disturbances, the pumps often tripped and the reasons are difficult to find out. When an abnormal condition occurs, the variable speed drive can perform self-diagnosis first, if the system has no problem it will reset and restart automatically, and find out the electric motor deceleration reasons in self-diagnosis by speed detection function during this period, and make it reaches the original speed, which requires the system should be integrated abnormal shutdown recovery function.
Free tripping operation function
Pump driving has torque decreased characteristic, effective overload protection function is important to make it running on the over-torque conditions. In this case, once the overload current reaches the set value, reduce the variable speed drive output frequency, that is stall in running. For such torque decreased loads, the variable speed drive can be running at the balance point for a short time, and restore original set frequency automatically after the load drops.
You may also like:
DC Motor now a days mostly used for precise speed control of Motor Application,in order to replace the DC motor with AC Induction Motor keep in mind that the initial Torque of the Motor of Load to be Calculate ...
In electronic design, they use "time simulation" (or "dynamic simulation"), which is an off-line calculation of how a system might respond to various inputs. The inputs are mathematical in this case, and the ...
For variable speed drives, there are two power semiconductor technologies employed: bridge rectifier and the output stage.
The bridge rectifier is made up of power rectifiers which are connected directly to ...
One of the ways these days that i check this process is by observing the winding process. By understanding the winding environment and not assuming anything, By taking part actively in DFM. By seeing what ...
For instance, let's take a transformer for an example. You test a transformer and you get short-circuit and open-circuit impedances and losses. Then, the most basic model for such transformer is a T circuit, ...
VSD blog: A deep observation of automation control industry, especially in AC motor variable speed drive for industrial motor controls. Hot Tags
Featured
7 months back I was involved in a harmonics evaluation study at Budweiser. This was one of many I've participated in over the past 20 years, basically because in facilities like ...
Most of variable speed drives are applying on high temperature fans, kiln head coal mill fans, kiln head surplus fans, raw mill circulating fans and so on. Two production lines ...
Variable speed drive application in purification system optimizes the system performance, improves purification effect, reduces power consumption greatly. According to related ...
The motor power factor does not make a big difference other than giving an idea of loading. In regards to the variable speed drive fixing power factor everyone is mostly correct. ...
A soft starter is a basic device which will ramp up the speed of your motor to full speed over a preset time, easing mechanical stress and also easing the high inrush currents ...
What's New
Variable Speed Drive Harmonics
Variable speed drive energy saving in cement industry
PLC and DAQ
Is it good to do preventive maintenance for variable speed drives
Does motor starts number affect motor life?
Variable speed drive for ID Fans in mining industry
Regenerative power frequency back to line power
Variable speed drive for axial-flow fans
Variable speed drive energy saving in cement industry
PLC and DAQ
Is it good to do preventive maintenance for variable speed drives
Does motor starts number affect motor life?
Variable speed drive for ID Fans in mining industry
Regenerative power frequency back to line power
Variable speed drive for axial-flow fans
