Level Override Conditions; Affect Of Backup Level Override; Additional Considerations; Pump Interlocks - Siemens SITRANS LUT400 Series Operating Instructions Manual

Settings
Parameter
2.9.1.2. Level Override Value
2.9. 1 .3. Discrete Input Number
2.9. 1 . 1 . Enable
When the level rises to 4.3 m and the switch is activated, the reading is forced to 4.3 m
where it stays until the switch is de-activated.

Level Override conditions

When the discrete input activates, the level output will immediately take on the value chosen
in step 1 above. The LUT400 LCD will indicate that the discrete input has been activated.
When a Backup Level Override condition clears (the discrete input is deactivated), the level
will return to the value determined from the ultrasonic transducer or, if no echo is available, the
device will enter the fail-safe condition.

Affect of Backup Level Override

The level produced by a Backup Level Override condition completely replaces the level that
would otherwise be produced by normal echo processing algorithms. This means that the
Backup Level will:
• drive all readings that depend on Level (for example: space, distance, and flow)
• drive level alarms
• appear in system logs
• affect pump control
• affect totalizers (OCM and Pumped Volume)

Additional considerations

A Backup Level Override condition will prevent a fail-safe condition from occurring: when a
backup level override condition is present, a fail-safe response will never occur. This allows
pumps and other controls such as level alarms to be active even during the backup level
override condition.

Pump Interlocks

Discrete inputs can be used to supply pump information to the SITRANS LUT400 to set
actions that will occur when a pump is determined to be in a failed state.
For an example of how to configure a pump interlock, see
page 87.

Switch (DI) Alarm

An alarm can be set to activate based on the state of a discrete input. See
Alarm
on page 70 for an example.
Page 70 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS
Sample Value
4.3
DISCRETE INPUT 2
ENABLED
Pump Control Interlocks
Switch (DI)
on
A5E33329501