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C'• Should a PLC failure ocCUrr, the station pumps is to be able to be controlled manually by switching <br />[lie pump local 1-1C1A switches to 1hw "HAND " or "OFF " position. The VFD pump specd in T-Ir-AND <br />is set oil the VFD LCD operator panel and keypad. <br />IV Overview of Well Pmmn Control <br />A. The constant speed well pumps are normally operated in AUTO triode, As the reservoir level drops <br />below, preset reservoir level setpoints, additional wells are called to rum and lill the reservoir. As the <br />level is restored, the wells are progressively shut afr. <br />V Overview of Bypass IVlode <br />A, The Bypass Mode can be enabled automatically by the PLC if all hooster pumps are "oft' and the <br />station discharge pressure still remains above setpoint for a significant time, This condition may <br />occur at night what demand Is law, and water is entering the distribution system from other <br />sources. <br />Fl. Il "the Bypass mode is enabled (all pampas are oil), and tlhe reservoir has capacity available; and the <br />system pressure is above a programmable (PLC /1IMI) setpoint, the PLC" will send a signal to <br />energize a solenoid valve on the Bypass Valve to at towv systoin flow back into the Reservoir. Irany <br />octhe allowable conditions are changed, the PLC will de- eugergizc the signal to the solenoid valve. <br />This procedure relieves the high system pressure. <br />Vi Re+servservoir I.evel Control :5tratog <br />A. Hardwired Functions <br />A low pressure switch shall be installed on the suction side of each booster pump. It t'he <br />suction pressurrc drops below the low pressure sotpa;iat, the pump ,hall step and a LOW <br />SUCTION PRFSSURE alarm shall be generated. The low Pressure alarm shall reset <br />arutonwaticu'lly when the suction pressure rises above setpoint. However, once a lows suction <br />alaim Is generated, the PLC shall not allow the pump to restart until the Reservoir has <br />attained a prograntrnable aninimurn level setpoint attained by Well Pump operation. <br />ft, pI :C" Functions <br />1. Continuously monitor the reservoir level <br />?. Alarm if the reservoir level exceeds a preset (HMI) High- Ili,gh or Lowv -Low level setpoint, <br />3. Generale: a warning if the reservoir level exceeds a High or Low level setpoint. <br />4. Local and Central HMI functions <br />S. Display the reservoir level and alarm the High -High, High, Low and Low-Low levels when <br />the alanin signal is generated by the PLC. <br />VII Booster Pura f�'orttrol <br />Gity of Sa�"i 46-905 <br />