Sewage pump blockage detection

Abstract

A method of monitoring a pump which operates to pump sewage from a wet well in which the current drawn by the pump is detected along with the speed of operation of the pump and the wet well level. The detected values are compared with stored values in a look up table to determine whether the pump is blocked.

1 . A method of monitoring a pump operable to pump sewage from a wet well comprising the steps of:
 detecting the current drawn by the pump;   detecting the speed of operation of the pump;   detecting the wet well level; and   comparing each of the detected values with stored values in a look up table to determine whether the pump is blocked.   
   
   
       2 . (canceled) 
   
   
       3 . A method as claimed in  claim 1  wherein the look up table is a look up table adapted to conform to the characteristics of a particular pumping station. 
   
   
       4 . A method as claimed in any preceding claim wherein the look up table comprises upper and/or lower threshold values for each parameter and wherein in order to determine that the pump is blocked, any two out of the three parameters or all three parameters may need to fall outside said threshold levels. 
   
   
       5 . (canceled) 
   
   
       6 . A method as claimed in  claim 4  wherein the look up table also comprises upper and/or lower super threshold levels wherein if the value of any one parameter falls outside the upper or lower super threshold, the pump is determined to be blocked. 
   
   
       7 . A method as claimed in  claim 6  wherein threshold levels and super threshold levels for one parameter depend on the detected value of another parameter. 
   
   
       8 . A method as claimed in  claim 1  wherein the method includes the step of determining a rate of change of any or all of: the current drawn by the pump; the speed of operation of the pump; and the wet well level and wherein the look up table comprises threshold levels and/or super threshold levels for the rates of change. 
   
   
       9 . (canceled) 
   
   
       10 . (canceled) 
   
   
       11 . A method as claimed in  claim 8  wherein to determine that the pump is blocked requires that two of the three or all three rates of change fall outside the the range defined by the lower and upper threshold levels or that at least one rate of change falls outside the super threshold levels. 
   
   
       12 . A method as claimed in  claim 11  wherein the or each threshold level and/or super threshold level is dependent on the determined rate of change of a different parameter. 
   
   
       13 . A method as claimed in  claim 1  wherein in response to a determination that the pump is blocked, a self cleaning procedure is initiated. 
   
   
       14 . A method as claimed in  claim 13  wherein the self cleaning procedure includes reversing the operating direction of the pump whereby the pump is run in reverese at a first specified speed for a first specified time interval, then forward at a second specified speed for a second specified time interval, this procedure being repeated three times. 
   
   
       15 . (canceled) 
   
   
       16 . A method as claimed in  claim 14  wherein if, upon resumption of normal operation it is determined that the pump is still blocked, an alarm is output. 
   
   
       17 . A method as claimed in  claim 1  wherein the method includes the step of storing current, pump speed and wet well level values for future reference; and/or the step of storing details of occasions upon which the self cleaning procedure was initiated and/or occasions upon which alarms are output. 
   
   
       18 . (canceled) 
   
   
       19 . A control unit for a pump operable to pump sewage from a wet well, the control unit comprising:
 current detection means;   pump speed detection means;   wet well level detection means;   memory means operable to store a look up table of current, pump speed and wet well level values; and   a processor operable to compare each of the detected current, speed and level values with values stored in the look up table to determine whether the pump is blocked.   
   
   
       20 . A control unit as claimed in  claim 19  wherein the control unit is operable in accordance with the method comprising the steps of:
 detecting the current drawn by the pump;   detecting the speed of operation of the pump;   detecting the wet well level; and   comparing each of the detected values with stored values in a look up table to determine whether the pump is blocked.   
   
   
       21 . A control unit as claimed in  claim 20  wherein the processor is operable to determine a rate of change of any or all of: the current drawn by the pump; the speed of operation of the pump; and the wet well level and is further operable to compare the determined rate of change values with rate of change values stored in the look up table to determine whether the pump is blocked. 
   
   
       22 . (canceled) 
   
   
       23 . A control unit as claimed in  claim 21  wherein the control unit is operable to initiate a self cleaning procedure if it is determined that the pump is blocked and wherein if it is determined that the pump is still blocked after the self cleaning procedure, the processor is operable to output an alarm signal. 
   
   
       24 . (canceled) 
   
   
       25 . A control unit as claimed in  claim 23  wherein the alarm signal is received by an alarm means, and wherein the alarm is either: an integral alarm means, or an external unit with a suitable connection to the control unit. 
   
   
       26 . (canceled) 
   
   
       27 . (canceled) 
   
   
       28 . (canceled) 
   
   
       29 . A control unit as claimed in  claim 25  wherein the memory means is operable to store current, pump speed and wet well level values for future reference and/or store details of occasions upon which the self cleaning procedure was initiated and/or occasions upon which alarms are output. 
   
   
       30 . (canceled) 
   
   
       31 . A control unit as claimed in  claim 29  wherein the control unit is provided with a user interface and wherein the user interface is operable to enable the cancellation of an alarm, the output of an alarm, the initiation of the self cleaning procedure and the transmission of data stored in the memory means to an external unit. 
   
   
       32 . (canceled) 
   
   
       33 . A pump operable in accordance with a method comprising the steps of
 detecting the current drawn by the pump;   detecting the speed of operation of the pump;   detecting the wet well level; and   comparing each of the detected values with stored values in a look up table to determine whether the pump is blocked.   
   
   
       34 . A pump incorporating a control unit comprising:
 current detection means;   pump speed detection means;   wet well level detection means;   memory means operable to store a look up table of current, pump speed and wet well level values; and   a processor operable to compare each of the detected current, speed and level values with values stored in the look up table to determine whether the pump is blocked.   
   
   
       35 . A sewage pumping station incorporating a pump operable in accordance with a method comprising the steps of
 detecting the current drawn by the pump;   detecting the speed of operation of the pump;   detecting the wet well level; and   comparing each of the detected values with stored values in a look up table to determine whether the pump is blocked.   
   
   
       36 . A sewage network incorporating one or more pumping stations incorporating a pump operable in accordance with a method comprising the steps of
 detecting the current drawn by the pump;   detecting the speed of operation of the pump;   detecting the wet well level; and   comparing each of the detected values with stored values in a look up table to determine whether the pump is blocked.