摘要:
A method for determining a change in a mass of a fan impeller. The method includes inducing a torque to the fan impeller and determining a change in the angular speed of the fan impeller, induced by the torque. A value for a first parameter representing a present mass of the fan impeller is determined on the basis of the change in the angular speed and the torque. The change in the mass is then determined on the basis of the first parameter and a second parameter representing the reference mass of the fan impeller.
摘要:
A method is disclosed for detecting the correct rotational direction of a centrifugal apparatus. The method can include detecting the correct rotational direction of the centrifugal apparatus based on an acceleration test and/or a deceleration test. The detecting of correct rotational direction of the centrifugal apparatus can include comparing an acceleration time (t1,acc) for a first direction with an acceleration time (t2,acc) for a second direction, whereby shorter acceleration time can be interpreted as an indication of correct rotational direction; and/or comparing a deceleration time (t1,dec) of the first direction with a deceleration time (t2,dec) of the second direction, whereby longer deceleration time can be interpreted as an indication of correct rotational direction.
摘要:
The invention relates to a method and to a corresponding system for controlling energy streams in order to connect operations of an electricity distribution network (1) and a heat distribution network (2) by means of an intermediate energy storage unit (3). According to the invention, the power balance and quality of current and voltage of the electricity distribution network (1) are adjusted by supplying the losses provided by adjustment of the electricity distribution network to the energy storage unit (3) in the form of heat, and from the energy storage unit the heat is extracted to the heat distribution network (2) according to the heat requirement of the heat distribution network.
摘要:
An exemplary method for determining a flow rate of a pump, includes measuring and storing the flow rate (QMean) when the pump is in operation, storing rotational speed (nMean) and torque (TMean) of the pump during measurement of the flow rate (QMean), determining torque (TManufacturer) corresponding to the measured flow rate (QMean), calculating a bias value of the torque (TBias) by comparing the torque determined from the characteristic curve (TManufacturer) and the stored torque (TMean) of the pump, and determining an operating point of the pump based on the bias value of the torque (TBias).
摘要:
A method and a system are disclosed in accordance with a pump controlled with a frequency converter. An exemplary method includes controlling the pump with a frequency converter, the frequency converter feeding a motor connected to drive the pump, providing a torque estimate (Test) and/or a rotational speed estimate (nest) of the motor from the frequency converter, forming one or more features (Feature1, Feature2, Feature3, Feature4) indicating cavitation or likelihood of cavitation of the pump and/or reverse flow of the pump using the provided estimates (Test, nest) and detecting cavitation or likelihood of the cavitation of the pump and/or reverse flow of the pump from one or more of the formed features (Feature1, Feature2, Feature3, Feature4).
摘要:
An exemplary frequency converter and method are directed to estimating an operation point of a pump when the QH characteristic curve of the pump is known. The frequency converter controls the pump, and a process curve is estimated when a first operation point of the pump is in the nominal range. The process curve defines a head as a function of volumetric flow. A rotational speed of the pump is determined and a QH characteristic curve of the pump is converted to a current rotational speed of the pump based on affinity laws. A second operation point of the pump is estimated by determining an intersection point of the converted QH characteristic curve and the estimated process curve.
摘要:
A method and an arrangement for detecting wear of a pump are disclosed, which pump is controlled with a frequency converter providing rotational speed and torque estimates, characteristic curves of the pump being known. An exemplary method includes obtaining a value representing the operating point of the pump by measuring the flow (Qact) or the head (Hact) produced by the pump; estimating the operating point of the pump by using a calculation based on the characteristic curves of the pump, the estimated rotational speed (nest) of the pump, and the estimated torque (Test) of the pump; calculating an estimation error from the value representing the operating point and from the estimated operating point; repeating the above steps during the use of the pump; and detecting the wear of the pump from the amplitude of the estimation error.
摘要:
A method and an arrangement for detecting wear of a pump are disclosed, which pump is controlled with a frequency converter providing rotational speed and torque estimates, characteristic curves of the pump being known. An exemplary method includes obtaining a value representing the operating point of the pump by measuring the flow (Qact) or the head (Hact) produced by the pump; estimating the operating point of the pump by using a calculation based on the characteristic curves of the pump, the estimated rotational speed (nest) of the pump, and the estimated torque (Test) of the pump; calculating an estimation error from the value representing the operating point and from the estimated operating point; repeating the above steps during the use of the pump; and detecting the wear of the pump from the amplitude of the estimation error.
摘要:
A method and arrangement for determining the flow rate (Q) produced by a pump, when the pump is controlled with a frequency converter, which produces estimates for rotational speed and torque of the pump, and the characteristic curves of the pump are known. The method includes determining the shape of a QH curve of the pump, dividing the QH curve into two or more regions depending on the shape of the QH curve, determining on which region of the QH curve the pump is operating, and determining the flow rate (Q) of the pump using the determined operating region of the characteristic curve.
摘要:
A method for determining a change in a mass of a fan impeller. The method includes inducing a torque to the fan impeller and determining a change in the angular speed of the fan impeller, induced by the torque. A value for a first parameter representing a present mass of the fan impeller is determined on the basis of the change in the angular speed and the torque. The change in the mass is then determined on the basis of the first parameter and a second parameter representing the reference mass of the fan impeller.