Pump system and method for operating the same
AssigneeEbara Corporation
InventorsYukio Murai, Seiichi Toguchi
Life of this patent
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Abstract
A pump system comprising a pump having a centrifugal impeller driven by an electric motor, a pair of upper and lower float switches for detecting a high water level HWL and a low water level LWL, respectively, a controller for outputting a control signal on the basis of preset rotational speeds for low and high-speed operations and a preset rotational speed increment rate, together with output signals from the upper and lower float switches, and a frequency converter for varying the rotational speed of the electric motor on the basis of the control signal from the controller, the pump system is capable of exhibiting the required pumping performance and of controlling the flow rate and the pump head.
Claims24
A pump system comprising:
- a pump having a centrifugal impeller rotated by means of an electric motor;
- a liquid level detector for detecting a liquid level;
- control means for outputting a control signal on the basis of preset rotational speeds and a preset rotational speed increment rate, in response to an output signal from a liquid level detector, and
- frequency converter means for initiating operation of said electric motor and for varying the rotational speed thereof on the basis of said control signal from said control means, wherein said preset rotational speeds include at least speeds for low and high-speed operations of said pump and said rotational speed of said electric motor is varied in accordance with said preset rotational speed increment rate from said low-speed operation to said high-speed operation.
A method for operating a pump system comprising a pump having a centrifugal impeller rotated by means of an electric motor;
- said method comprising steps of
- detecting a liquid level to be pumped out;
- outputting a control signal on the basis of preset rotational speeds and a preset rotational speed increment rate in response to said detected liquid level, to initiate operation of said electric motor and
- varying the rotational speed of said electric motor on the basis of said output control signal, wherein said preset rotational speeds include at least speeds for low and high-speed operations of said pump including varying said rotational speed of said electric motor with said preset rotational speed increment rate from said low-speed operation to said high-speed operation.
A method for operating a pump system comprising a pump having a centrifugal impeller rotated by means of an electric motor;
- said method comprising steps of
- detecting a liquid level to be pumped out;
- outputting a control signal on the basis of preset rotational speeds and a preset rotational speed increment rate in response to said detected liquid level, to initiate operation of said electric motor and
- varying the rotational speed of said electric motor on the basis of said output control signal, wherein said preset rotational speeds include at least speeds for low and high-speed operations of said pump including varying said rotational speed of said electric motor with said preset rotational speed increment rate from said low-speed operation to said high-speed operation;
- and
- comprising the further steps of
- detecting choking of said pump,
- attempting to start said choked pump by means of said electric motor when said pump is choked,
- repeatedly attempting to start said pump by means of said electric motor after stopping for a predetermined time if said pump does not clear, and
- suspending the operation of said electric motor if said pump does not clear even after having attempted to start said pump a predetermined number of time.
A method for operating a pump system comprising a pump having a centrifugal impeller rotated by means of an electric motor;
- said method comprising steps of
- detecting a liquid level to be pumped out;
- outputting a control signal on the basis of preset rotational speeds and a preset rotational speed increment rate in response to said detected liquid level, to initiate operation of said electric motor and
- varying the rotational speed of said electric motor on the basis of said output control signal, wherein said preset rotational speeds include at least speeds for low and high-speed operations of said pump including varying said rotational speed of said electric motor with said preset rotational speed increment rate from said low-speed operation to said high-speed operation;
- and
- comprising the further steps of
- detecting choking of said pump,
- attempting to start said choked pump by means of said electric motor when said pump is choked,
- carrying out the second and subsequent attempts at restarting by reversely rotating said electric motor if said pump does not clear.
In a method of operating a pump system in a small-sized combined septic tank equipment including a flow control tank and an anaerobic tank, wherein said pump system is installed in said flow control tank for supplying sewage from said flow control tank into said anaerobic tank, wherein said pump system is operated in accordance with a method comprising the steps of:
- detecting a liquid level to be pumped out;
- outputting a control signal on the basis of preset rotational speeds and a preset rotational speed increment rate in response to said detected liquid level, to initiate operation of said electric motor and
- varying the rotational speed of said electric motor on the basis of said output control signal, wherein said preset rotational speeds include at least speeds for low and high-speed operations of said pump including varying said rotational speed of said electric motor with said preset rotational speed increment rate from said low-speed operation to said high-speed operation.
In a method of operating a pump system in small-sized combined septic tank equipment including a raw sewage tank, a flow control tank, an anaerobic tank and an aerobic contact aeration tank arranged in series, wherein said pump system is installed in said flow control tank for supplying sewage from said flow control tank into said anaerobic tank, wherein said pump system is operated in accordance with a method comprising steps of:
- detecting a liquid level to be pumped out;
- outputting a control signal on the basis of preset rotational speeds and a preset rotational speed increment rate in response to said detected liquid level to initiate operation of said electric motor, and
- varying the rotational speed of said electric motor on the basis of said output control signal, wherein said preset rotational speeds include at least speeds for low and high-speed operations of said pump including varying said rotational speed of said electric motor with said preset rotational speed increment rate from said low-speed operation to said high-speed operation.
Dependencies are inferred from the claim text.