| Window
Current Sensing
For Pump Protection There are a variety of events that can cause problems in a pumping system. Suction side problems like loss of prime, low reservoir, cavitation, suction leaks or a broken impeller can stop flow even though the motor is still running. Discharge problems like obstructions, broken valves, jammed impellers, or mechanical problems like seized bearings or drive problems can cause the pump motor to slow down or lockup. Most of these events can be detected by monitoring the current flow to the motor. Since suction and discharge problems have the opposite affect on motor’s current, a window current sensor is required to provide full pump motor protection. The ECSW Series of "window" current sensors provides an overcurrent and undercurrent trip point in one unit. The overcurrent set point is adjusted above normal operating current and the undercurrent set point is adjusted slightly below normal operating current. This provides a "window" of normal operating current for the pump motor. If the pump is unloaded due to suction side problems, the current drops below the undercurrent set point and the ECSW’s output relay energizes (or de-energizes). If the load current increases due to a discharge side restriction or a mechanical problem, the current increases above the overcurrent set point and the output relay responds. With the mode selector switch set for "latched" (manual reset), the ECSW relay will not allow the pump to cycle again after it trips until the control circuit is reset. Resetting the ECSW is far easier than traditional overloads since it can be reset by opening a normally closed reset switch located on the control panel door or in a remote location. |
 PCC=Pump Contactor Coil PC=Pump Contactor CS=Current Sensing Torroid FSW=Float Switch RSW=Reset Switch OL=Overload F=Fuse |
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