Operating modes of wastewater pumps

The operating mode defines how long a pump may be run in order to protect it from overheating. To this end, the running time and pause times are set in relation to one another. There are various classes of operating modes, which may be as follows: 

• S1 = Continuous operation
  Although this is referred to as continuous operation, this does not mean that the pump runs round the clock for an unlimited period. The manufacturer’s specifications regarding service life and running time must be observed.
   
• S2–S9 = Intermittent
  operation Intermittent operation means that the pump cannot be operated continuously, as this would cause it to overheat after a certain time and trigger the motor protection to shut it down. Operating mode S3 covers wastewater pumps designed for intermittent operation. The calculation of the operating time always refers to a period of 10 minutes.
   
• Operating mode S3 – 20%
  Means that the pump has an operating time of 20% and can therefore run for a maximum of 2 minutes within 10 minutes, with 8 minutes of downtime.
   
• Operating mode S3 – 4 min.
  This means that the pump has 4 minutes of operating time and 6 minutes of idle time within a 10-minute period.

The appropriate operating mode for your lifting station or pumping station depends, therefore, on how frequently and in what volumes wastewater is discharged via the system. At KESSEL, you can obtain wastewater pumps in various operating modes that are precisely tailored to your specific application. 

Nevertheless, it can generally be said that lifting stations designed to discharge rainwater should be equipped with an S1 pump (continuous duty). Lifting stations for domestic wastewater, on the other hand, are usually equipped with an S3 pump (intermittent duty), as the inflow of wastewater is discontinuous.