What causes the secondary pump of a series pump not to start?
Thread Content
In a closed-loop system with two single-stage pumps connected in series, if the first pump is started first, there will be a pressure of around 0.3 MPa at the inlet of the second pump; under such conditions, the second pump cannot start； The secondary pump needs to be turned on first, followed by the primary pump, in order to start them all. Why is that?
This is related to the design inlet pressure of the pump
The secondary pump won’t start – what are the symptoms? Is it overload? It is recommended to try closing the outlet valve of the secondary pump first, then turning on the primary pump, and subsequently starting the secondary pump. Once the secondary pump is running, open its outlet valve finally. Because once you start the primary pump, the pressure at the inlet of the secondary pump becomes very high; if the pressure at the outlet of the secondary pump is low, it’s easy for the pump to become overloaded. The problem is that as soon as the secondary pump starts operating, the overcurrent protection triggers and the circuit breaks.
The analysis on the 3rd floor makes sense: start with the first-stage pump first. The pressure at the inlet of the second-stage pump is high, which results in an excessive flow rate from the pump and a significant increase in power consumption, leading to overload.