Overload design and protection of axially split pump

In general the pump in the open, power is always increased with increasing flow, that is to say, the power curve is an increase with the rising flow curve, the use of the pump will bring about a problem: when the pump is in operation at the operating point for design, in general, less than rated power of motor power the use of pump, this pump is safe; but when the pump head decreases, the flow will increase (from the pump performance curve can be seen), power is also increased.
When the flow rate exceeds the design point flow and reach a certain value, the pump input power may exceed the motor rated power and cause motor overload and burn. Motor overload operation or protection system action to stop the pump rotation; or to protect the system failure to burn the motor.
In the pump head below the design point lift usage, in practice is often encountered, a situation is when the pump selection, pump head selected too high, but the actual use is to lower the lift pump use; another situation is in use the pump operating point is not well established, in other words the flow of pump need to be adjusted; there is a need to change the location of pump use. These three conditions may cause the pump to overload and affect the use of the pump can * * * *. It can be said, for the pump without the characteristics of the whole pump (including submersible sewage pump), the scope of its use will be largely restricted.
Full lift characteristics (also known as the so-called non overload characteristics) refers to the power curve increase with the rising flow speed is very slow, it is more desirable when the flow rate increased to a certain value, the power will not rise again, it will decline, that is to say the power curve is a hump curve, if such if we just choose the motor rated power is slightly more than the power of hump point value, then in 0 traffic to the entire range of maximum flow, whether you run on that one point, the pump power will not exceed the motor power and the pump overload, to have the performance of pump, whether it is the selection or use, will be very convenient. In addition, the motor power is not too large, can save considerable equipment costs.