Data Flow Systems TCU800, Installation And Operation Manual

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21
U n i t O v e r v i e w
Off Level
Minimum operational level of a tank. All pumps are stopped when the tank’s
level is
above
the Off level.
Lead Level
Lead (first) pump is started. Lead is active when the tank’s level is
below
the
Lead level.
Lag Level (duplex and triplex stations
only) Lag (second) pump is started. Lag is active when the tank’s level is below the
Lag level.
Lag2 Level (triplex stations only)
Lag2 (third) pump is started. Lag2 is active when the tank’s level is
below
the Lag2 level.
Low Level
All pumps are stagger started and alarms are activated. Low is active when
the tank’s level is
below
Low level. Must be set below all other levels.
Analog System (Pressure Transducer)
In an analog system, pumps are controlled by a variable, transducer-supplied 4-20 mA or 0-5 V input that is wired to the
TCU’s analog input. The operator sets the 4 mA or the 1 V input equal to the transducer’s low range (in feet) and the 20
mA or 5 V input equal to the transducer’s high range (in feet). Low and High levels, as well as staging levels for the Lead,
Lag, and Lag2 pumps are also set by the operator. The TCU interprets the input signal and starts or stops pumps according
to the configured staging levels.
The TCU pump control operation functions with eight possible staging levels: Low, Lead Off, Lead, Lag Off, Lag, Lag2
Off, Lag2, and High.
An analog system has several options available for handling transducer faults:
• High and/or Low Float Override. Use a high and/or a low float to issue an alarm and override normal pump control.
• Switch to normal float behavior (Floats). This option requires an Off float to shut off the pumps and a minimum of one
float (Lead to High) to start the pumps.
• Switch to a second analog input (Analog2).