Data Flow Systems TCU800, Installation And Operation Manual

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116
A p p e n d i x I
Concurrent
transducer low
and high float
conditions
• Transducer
fault alarm
• Low well alarm
• High well
alarm
All pumps on Low well, high well, and transducer fault
alarms are generated. High float condition takes
precedence over the transducer low condition and
all pumps are staggered on. Minimum run and off
timers are applied. Normal pump operation resumes
if both conditions clear. The transducer fault alarm
remains active until the TCU has been reset.
Low float
condition
Low well alarm All pumps off A low well alarm is generated. All pumps shut
off. When the low float condition clears, normal
pump operation resumes. IMPORTANT: Low float
condition has precedence over all other faults and
alarms, including high float and high level. If a
low float condition exists, no pumps are allowed to
start.
4-20 mA or 0-5 VDC Transducer with Floats Backup (Pump Down Mode)
This configuration is for a system using 4-20 mA or 0-5 VDC transducers. It uses float inputs to operate the pumps in the
event of a transducer fault.
Float Fault Mode requires an OFF float to shut off pumps, and a minimum of one float (Lead to High) to start
pumps. Do not configure Float Fault Mode if there is not an OFF and Start float wired!
Float sequence faults are disabled in this mode. Minimal floats can be used to operate the station until the transducer fault
has been resolved, but the TCU utilizes all the float inputs the same as if configured for Floats. The Off through Lag2 float
inputs are ignored when the transducer is not faulted, but these inputs can only be used for the specified floats. The High
Float Override can be enabled to allow pumping if the off float fails.
To prevent short cycling on high float transitions, the pumps adhere to the configured minimum run and minimum off
timers. In the example below the pumps will run a minimum of one minute and remain off a minimum of 30 seconds
regardless of the frequency of float transitions. Minimum run and off timers apply to all pump operations – not just fault
conditions – so these timers should be set considering the pump and well characteristics during normal pump cycles.
Notes:
• If a high and a low float condition exist simultaneously, the low float condition takes precedence and no pumps will be
started. If the transducer is a bubbler system, an optional Noise Fault configuration can be enabled to sense a bubbler
pump failure and generate a transducer fault alarm.
• If a high float condition exists and the Off float is off, no pumps will be started unless the High Float Override option
has been enabled.
• Once a transducer fault has occurred the TCU will remain on float control until it has been reset.