Importance

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Abstract

There is disclosed an electro-mechanical sequencer to equalize the running time of multiple (typically four) pumps in a common sump at a sewage treatment plant or the like. The sequencer includes a solid state binary counter receiving an input at an all-pumps-off condition. The binary counter operates a pair of multi-pole-double-throw relays. Control signals (typically four) from float valves or other sensing devices to the pump motors are routed through the first relay and then the second relay; one of the relays shifts the connection of its inputs and outputs by one position; the other relay shifts by two positions. Upon successive input signals to the binary counter the relays are changed from no-shift, to one position shift, two position shift, three position shift, and back to no-shift (in four pump systems). Three pump systems return to no-shift after the two position shift. Control signals through the relays do not pass through semiconductor devices and failure of sequencer operation leaves the pump system fully operative, but without the sequencing function.

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First Claim