Applications in the Water / Wastewater Market
 
Isolated analog and discrete modules improve reliability in municipal water delivery system.

The City of Twin Falls decision to retrofit its existing wastewater plant with Allen-Bradley SLC 500 equipment was based on the increase in efficiency and reliability that the solution offered.  Automating key processes greatly reduced downtown and increased the cities diagnostic capabilities. The upgrade occurred in 5 phases, each phase representing reconstruction of 5 nodes within the plant.  Each node is controlled by a SLC 500 containing a variety of Spectrum Controls channel-to-channel Isolated Analog  Input and Output Modules.  The PLCs communicate between each other via Data-Highway Plus network.
 

The automation encompassed the following processes:

  • Control of Oxidation system
  • Polymer feed system control
  • Coagulation process control
  • Level monitoring

Spectrum Controls isolated analog modules offer 750V channel to channel isolation.  This eliminated cross-talk between acquisition and control signals, especially in electrically noisy environments. Jim O’Connor, consulting engineer with CH2MHill in Boise chose the modules for their reliability and performance.

The oxidation system uses a motor controlled by a variable frequency drive using a 4-20mA signal as the driver. The 1746sc-INO4Vi allows for the ramp up and down of the motor giving greater flexibility for motor control without fear electric noise disrupting the control signal.

The polymer feed system is used to separate the solid phase from the water phase, a batching process involving pumping and mixing facilitates the coagulation. The 1746sc-INO4vi is used for motor control and for alarming in case of pump failure

References:
Colombia Electric, Authorized Allen-Bradley Distributor, Boise, Idaho
Control Tech, Electrical Contractor, Ontario,OR
CH2Mhill, Consulting Engineering , Boise office

Referenced Product:
1746sc-INI4i, 1746sc-INI4vi - Isolated Analog Input Modules - Datasheet
1746sc-INO4i, 1746sc-INO4vi - Isolated Analog Output Modules - Datasheet
1746-Ix8i - Isolated Discrete Input Modules - Datasheet
1746sc-OAP8i - Isolated Triac Output Module - Datasheet