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<br />City of Arden Hills, MN – 25X.137753 LIFT STATION CONTROL SYSTEM <br />January 2026 PAGE 26 90 04-10 <br />©2026 Design Tree Engineering, Inc All Rights Reserved <br />7. A relay shall be provided for monitoring PLC fault. PLC shall keep the relay open, upon failure of PLC <br />to maintain the relay position, the relay shall close, an alarm shall be indicated on the SCADA <br />system, and the float backup control mode shall be activated. <br />K. Level measurement: <br />1. A submersible level transducer is to be mounted in the wetwell. <br />a. The transducer shall create a 4-20mA signal proportional to the wetwell level and shall be <br />monitored by the lift station control system. <br />b. The wetwell level is to be displayed and trended on the control system interfaces and used for <br />control as described above. <br />c. Operator is to utilize the control system interface screens to enter a High and Low Wetwell <br />Alarm level setpoints. Upon the measured wetwell level rising or falling to the associated level <br />for an operator adjustable amount of time, the control system shall signal the appropriate <br />alarm. <br />L. Pump Run Monitoring: <br />1. The control system shall monitor motor controller auxiliary contacts or outputs for indication of run <br />status and for run time accumulation. <br />2. Run time meter shall be provided on the control panel inner door to indicate the totalized run time. <br />Run time meter shall track operation anytime the pump is running. <br />3. Omnisite to monitor run times. Run time shall be shown in daily, weekly, and total on Omnisite. <br />M. Pump fail monitoring: <br />1. The control system shall monitor motor controller auxiliary contacts or outputs for indication of fail <br />status. Upon activation of such signal, the pilot light shall indicate a pump fail alarm. <br />2. If a pump is required to run, and a run signal is not received by the control system after an <br />adjustable time delay expires, the control system and pilot lights shall indicate a pump fail alarm. <br />3. The control system shall monitor a 4-20mA speed feedback signal from the VFD. If the speed <br />feedback doesn’t match the desired operating speed after an adjustable setpoint triggered when <br />the pump is required to run, the control system shall signal a pump failure alarm. <br />4. An associated pump failure red pilot light shall illuminate on the control panel inner door. This shall <br />occur regardless of the mode of control the motor control system is in. <br />5. Omnisite shall monitor these signals and provide a remote alarm upon activation of signals. <br />N. Pump protection signals: <br />1. Temperature sensors supplied with the pump shall initiate a pump fail alarm and stop the pump <br />upon an over temperature condition. Pump shall be locked out until manually reset. Temperature <br />monitoring units shall be furnished by the pump supplier for installation in the lift station control <br />panel. This shall create a pump failure alarm. <br />2. Seal chamber moisture sensors supplied with the pump shall initiate a pump fail alarm upon <br />detection of moisture in the seal chamber. Moisture monitoring units shall be furnished by the <br />pump supplier for installation in the lift station control panel. A moisture alarm bypass switch shall <br />be provided inside the control panel’s inner door to allow disconnecting the moisture alarm from <br />any alarm horn, exterior alarm light, and telemetry, if provided. Provide an auxiliary contact on the <br />associated pump circuit breaker (and slave relays as required) to disconnect the moisture sensor <br />circuitry when the circuit breaker is in the off position. <br />3. Provide an auxiliary contact on the associated pump circuit breaker (and slave relays as required) to <br />disconnect the pump protection signals circuitry when the circuit breaker is in the off position.