Pump system

Abstract

A pump system for a pressure sewer system, comprising a pump, a cutter and an electric motor configured to drive the pump and the cutter; the pump system comprises a current sensor that measures the electric current provided to the motor and the controller stops the operation of the motor if the current drawn by the electric motor exceeds the predetermined threshold.

1 . A pump system for use in a pressure sewer system, comprising:
 a pump;   a cutter; and   an electric motor configured to drive the pump and the cutter;   wherein the pump system further comprises:   a current sensor configured to measure the electric current provided to the motor; and   a controller that is configured to monitor the electric current measured by the current sensor during operation of the pump system and, if the measured electric current exceeds a predetermined threshold, stop the operation of the motor.   
   
   
       2 . A pump system according to  claim 1 , wherein the controller is further configured to reverse the motor by a predetermined amount after stopping the motor due to the electric current exceeding said predetermined threshold. 
   
   
       3 . A pump system according to  claim 1 , wherein the controller is further configured to re-start the motor after a predetermined delay. 
   
   
       4 . A pump system according to  claim 1 , wherein the pump system further comprises an audible and/or visible alarm;
 the controller is further configured to monitor the frequency with which it stops the operation of the motor due to the electric current exceeding said predetermined threshold; and   if the controller stops the operation of the motor more than a predetermined number of times in a given time period, the controller activates said alarm.   
   
   
       5 . A pump system according to  claim 4 , wherein the controller is configured such that, if after the alarm has been activated, the motor is re-started and the current provided to the electric motor does not exceed said predetermined level, the alarm is deactivated. 
   
   
       6 . A pump system according to  claim 1 , wherein the controller is configured such that; if the measured electric current exceeds a second predetermined threshold, lower than the first predetermined threshold, for a predetermined period of time, the controller stops the operation of the motor for a second predetermined period of time. 
   
   
       7 . A pump system according to  claim 1 , wherein the controller further comprises a memory configured to store data relating to the electric current provided to the motor; and the pump system further comprises a data output for outputting the data stored in the memory. 
   
   
       8 . A pump system according to  claim 7  wherein the memory stores at least one of the total number of times the controller has stopped the operation of the motor due to the electric current exceeding at least one of said predetermined threshold and said second predetermined threshold; the frequency with which the controller has stopped the operation of the motor due to the electric current exceeding at least one of said predetermined threshold and said second predetermined threshold; the total time that current is provided to the motor; and a record of the current supplied to the motor over time. 
   
   
       9 . A pump system according to  claim 1 , wherein the pump is a positive displacement pump. 
   
   
       10 . A pump system according to  claim 1 , wherein the cutter comprises a rotating serrated impeller. 
   
   
       11 . A pump system according to  claim 1 , wherein the motor is a single-phase motor with capacitor-start. 
   
   
       12 . A pressure sewer system, comprising:
 a sewage pipe for conveying sewage under pressure;   at least one sewage store tank; and   a pump system according to any one of the preceding claims, configured to pump sewage from said sewage store tank into said sewage pipe.   
   
   
       13 . A pump system according to  claim 12 , further comprising a level sensor system, configured to determine the sewage level in the sewage store tank;
 wherein the controller of the pump system, is further configured to start operation of the motor when the sewage level in the sewage store tank exceeds a predetermined level.   
   
   
       14 . A pump system according to  claim 12 , wherein the controller of the pump system is configured to stop the operation of the motor if the sewage level in the sewage store tank drops below a second predetermined level. 
   
   
       15 . A pump system according to  claim 12 , wherein the controller of the pump system is configured to stop the operation of the motor if a predetermined time has elapsed. 
   
   
       16 . A method of controlling a pump system for use in a pressure sewer system, said pump system comprising a pump, a cutter and an electric motor configured to drive the pump and the cutter; and the method comprising:
 measuring the electric current provided to the motor during operation of the pump system and, if the measured electric current exceeds a predetermined threshold, stopping the operation of the motor.   
   
   
       17 . A method according to  claim 16 , further comprising reversing the motor by a predetermined amount after stopping the motor due to the electric current exceeding said predetermined threshold. 
   
   
       18 . A method according to  claim 16 , further comprising re-starting the motor after a predetermined delay. 
   
   
       19 . A method according to  claim 16 , further comprising monitoring the frequency with which the operation of the motor is stopped due to the electric current exceeding said predetermined threshold; and
 if the operation of the motor is stopped more than a predetermined number of times in a given time period, activating an audible and/or visible alarm.   
   
   
       20 . A method according to  claim 19 , wherein, if after the alarm has been activated, the motor is re-started and the current provided to the electric motor does not exceed said predetermined level, the alarm is deactivated. 
   
   
       21 . A method according to  claim 16 , wherein, if the measured electric current exceeds a second predetermined threshold, lower than first predetermined threshold, for a predetermined period of time, operation of the motor is stopped for a second predetermined period of time. 
   
   
       22 . A method according to  claims 16 , further comprising storing data, relating to the electric current provided to the motor, in a memory. 
   
   
       23 . A method according to  claim 22 , wherein the memory stores at least one of the total number of times the controller has stopped the operation of the motor due to the electric current exceeding at least one of said predetermined threshold and said second predetermined threshold; the frequency with which the controller has stopped the operation of the motor due to the electric current exceeding at least one of said predetermined threshold and said second predetermined threshold; the total time that current is provided to the motor; and a record of the current supplied to the motor over time.