Structure Data Type Definitions

Structure Data Type Definitions - CavtProt

Overview

Structure data types serve as the major input and output data carriers between different function blocks, configuration, and parameterization data.

The following section lists the names of structures (data types) that are used in this function block, followed by a table that describes the elements of structure.

NOTE: For the structure data types that are used from this function block and others, refer to the Common Structure Data Type Definitions chapter.

Structure: stCavtInit

The stCavtInit structure data type contains the initialization data for the CavtProt function block.

Element of stCavtInit	Data Type	Description
rNpshPlus	REAL	Defines the NPSH+ value as defined by the manufacturer of the pumps. If the suction pressure drops below this value, the pumping application is stopped and an alarm is detected.
rNpshAlrtOn	REAL	Defines the lower suction pressure limit value. If the suction pressure drops below this value, the cavitation protection procedure starts and an alert is detected. Range: rNpshAlrtOn > rNpshPlus
rNpshAlrtOff	REAL	Defines the upper suction pressure limit value. If the suction pressure exceeds this value, the cavitation protection procedure stops and an alert is cleared. Range: rNpshAlrtOff > rNpshAlrtOn
rSpMin	REAL	Defines the minimal setpoint value for the pressure. The setpoint adaptation of the function uses this limit value for the minimum of the adapted pressure setpoint value. After a reset of a detected NPSH+ alarm, this is the first (minimum) pressure value that is used as a setpoint. In the course of time, the pressure setpoint is adjusted according to the measured suction pressure value. Range: rSpMin > 0
rTn	REAL	Defines the stage time (Tn, in milliseconds) for the reference ramp. Range: rTn > 0.0 ms The time required to increase the correction value by 1 unit.

Structure: stCavtErr

The stCavtErr structure data type is used to indicate alarms or alert states detected during cavitation protection.

Element of stCavtErr	Data Type	Description
stCavtAlrm	stCavtAlrm	Structure data type for detected alarms.
stCavtAlrt	stCavtAlrt	Structure data type for detected alerts.

Structure: stCavtAlrm

The stCavtAlrm structure data type is a substructure of stCavtErr. The stCavtAlrm structure data type is used to indicate the alarm states detected during cavitation protection.

Element of stCavtAlrm	Data Type	Description
xSuctPresNpsh	BOOL	When TRUE, the suction pressure has dropped below the NPSH+ value.
xSuctPresSta	BOOL	When TRUE, it has been detected that the suction pressure value is not valid.

Structure: stCavtAlrt

The stCavtAlrt structure data type is a substructure of stCavtErr . The stCavtAlrt structure data type is used to indicate the alert states detected during cavitation protection.

Element of stCavtAlrt	Data Type	Description
xSuctPresLim	BOOL	When TRUE, the actual suction pressure has dropped below the lower suction pressure limit value. As a result of this detected alert state, the cavitation protection function is started.
xReserve	BOOL	This parameter is currently not used.