| 摘要 |
The present invention is a controller specifically for pumps, making the benefits of variable frequency drive (VFD) technology more accessible to pump users. The present invention incorporates pump-specific system optimization software, an industrial grade drive, and a menu-driven user interface, offering protection, reliability, and ease of use not possible with other variable frequency drives. |
| 主权项 |
1. A method of controlling operation of a centrifugal pump in a fluid pumping system having a variable frequency drive (VFD) powering an alternating current (AC) motor which turns said centrifugal pump, said method comprising:
internally monitoring automatically output current and voltage of the VFD to the AC motor without the need for an external sensor; calculating automatically output power based on monitored values of said output current and voltage and not on torque or speed of the AC motor; checking automatically whether said calculated output power is above a predetermined high power limit for a desired setpoint; checking automatically whether said calculated output power is below a predetermined low power limit for said desired setpoint, wherein said high and low power limits vary depending upon pump operating speed; receiving feedback from an external process sensor, wherein said feedback is indicative of said desired setpoint; and initiating automatically a first predetermined response action if said calculated output power is either above said predetermined high power limit or below said predetermined low power limit; wherein said high power limit is set to lowest of either power at the end of a performance curve of the pump, maximum rated motor power, or power rating of magnetic coupling of a magnetic drive pump or a canned motor pump, and wherein said low power limit is set for the highest of the performance curve of the pump or power required at minimum continuous recommended flow; using a high power level delay which is a time period that the output power must exceed the high power limit before said predetermined response action is initiated; monitoring an externally provided analog sensor signal; and initiating automatically a second predetermined response action if in a signal threshold level mode said analog sensor signal crosses one or both preset levels in the same direction, wherein each of said preset levels can initiate a separate response, or if in boundary mode, said analog sensor signal rising above a preset maximum value or drops below a preset minimum value, and in both modes, if after expiration of a time delay said analog sensor signal is still above one or both said preset levels if in a signal threshold level mode, or above or below said present maximum and minimum present values, respectively, if in boundary mode. |
