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在化工生产中,一些流体介质的输送大多数是利用离心泵来实现的,并且生产工艺对输送介质的流量往往有一定的要求,这就需受有流量报警控制装置。本文介绍的是一种利用检测泵电机的功率因数来间接测量泵的流量的低流量报警装置。图1 Q-N性能曲线表明离心泵的流量Q与轴功率N之间的关系,曲线上的各点表明泵在提供某—流量时,需要输入的轴功率数值,随着流量Q的增加,轴功率平缓上升,流量为零时轴功率最小。反过来说,当泵的流量小时,电机的负载就小,这时的功率因数则低;当泵的流量大时,电机的负载就大,此时的功率因数就大。异步电机空载时功率因数cosφ仅为0.2～0.3,而满载时的功率因数cosφ可
In chemical production, most of the fluid medium is delivered by centrifugal pumps, and the production process often has certain requirements on the flow of the medium to be transported, which requires a flow alarm control device. This article describes a low-flow alarm that measures the pump’s flow indirectly by using the power factor of the pump motor. Figure 1 QN performance curve shows the centrifugal pump flow Q and shaft power N relationship between the points on the curve that the pump in providing a - flow, the need to enter the shaft power value, as the flow rate Q increases, the shaft power Smooth rise, the flow of zero shaft power minimum. Conversely, when the pump flow is small, the motor load is small, then the power factor is low; when the pump flow is large, the motor load is large, the power factor is large. Asynchronous motor no-load power factor cosφ only 0.2 ~ 0.3, and full load power factor cosφ