11.125.360 Sequence of operation.
The starting and stopping sequences of pump operation shall be as follows:
After a start signal is initiated from the first step of the control system, after a predetermined time delay (on-delay timer, adjustable zero to 60 seconds), the starter of the lead pump motor shall be energized, provided the following permissives (as applicable depending on the function of the pumping station in the system) are met:
(a) In-Line Booster Stations.
(1) Pump control valve on discharge side is closed as sensed by limit switch (as applicable).
(2) There is no pump lock-out due to overload, valve failure, high bearing temperature or other abnormalities, as sensed by the lock-out relay (device 86).
(3) There is sufficient water available on the suction side, as sensed by an electrode type water sensor.
(b) Booster Stations with Pumped Storage.
(1) Pump control valve on discharge side is closed as sensed by limit switch (as applicable).
(2) There is no pump lock-out due to abnormalities as sensed by the lock-out relay.
(3) There is sufficient water available in the reservoir.
(4) The altitude or reservoir fill valve is closed as sensed by limit switch on the altitude valve. (If the reservoir fill valve is open, closing of the reservoir fill valve shall be initiated when any pump is called to start.)
(c) In the case of pumps with automatic pump control valves, after the motor has started, the associated discharge valve shall open and reset the overall sequence timer if the pump is operating satisfactorily and the discharge valve has fully opened within a predetermined time period. When a stop signal is initiated from the control system, after a predetermined time delay, the solenoid operated discharge valve shall be caused to close. When the valve has reached the nearly closed position, a limit switch mounted on the valve shall open momentarily to stop the motor. (This limit switch does not open on the opening cycle of the valve.)
(d) If the system demand (pressure, flow, or level as the case may be) cannot be satisfied by the first pump, the second step in the control system shall cause a second pump to start as outlined above, and shall continue to operate until system demand can be satisfied by the lead pump alone at which time the second pump shall be stopped as outlined above. If the lead pump and the first lag pump are not able to meet the system demand, the second lag pump shall start, etc. (28-ME-DG-02 § 23.7)