Unit phase properties

Unit Phase Properties

The unit phase properties define the essential properties for every phase that should be made available on the unit. The properties are configured on the unit phase (Area/Process Cell/Unit/Unit Phase) in DeltaV Explorer.

For each phase class, the user configures the following properties:

  • Unit Phase Name - The name of the unit phase. The unit phase name defaults to the phase class name and cannot be modified in the unit phase.

  • Alternative unit phase name for operator interface - The user can configure the name seen by the operator for this phase algorithm when it runs in this unit module. For example, the operator could see FILL for FILL_CHARGE_TANK or FILL_FERMENTOR. The unit phase name defaults to the phase class name, but the user can change it as long as it does not conflict with other unit phase names in the same unit module.

  • Unit Phase Description - To record how this unit phase is used in the system, the user can enter a description.

  • Phase Type - Choices are Disabled, Controller, and External Phase. A Disabled unit phase does not download. A Controller unit phase is downloaded if the aliases have been resolved. The External Phase creates a link to an already created External Phase (external to the DeltaV system).

  • Scan Rate Multiplier - The user enters a number in this field to make the unit phase execute at a slower rate than the unit module. For example, if you enter 3, then the phase executes every third time the unit module executes. To see the module's scan rate, look at the module properties.

  • Always in Memory - When Controller is checked for the phase type, this option is available. When selected, the phase is always able to be loaded. This protects against a possible over-commitment of controller memory resources that would keep the phase from running.

  • Simulate - When checked, the phase can be run using the Recipe Simulator application. This option is available for all the phase types.

  • External Phase - When the unit phase type is External Phase, you must enter (or browse to) the phase class that the external phase is based on.

Note:

Expressions in phase algorithms cannot use unit phase names to address phase parameters because they might be different on each unit.

The unit phase will, by default, have a system-wide unique name. However, the unit phase can be given a common shortened name that the operator will see and use.

Note:

The shortened phase name must be unique on that unit.

For example, there are phase classes named REACTOR_FILL and DRYER_FILL. When a unit phase is created based on REACTOR_FILL, the name is R1/REACTOR_FILL and when a unit phase is created based on DRYER_FILL, the name is D1/DRYER_FILL. By changing the Unit Phase Name in the unit phase properties for both DRYER_FILL and REACTOR_FILL to FILL, the operator sees and works with the name FILL in the Batch Operator Interface.

Note:

Use caution when shortening the phase names as the names do not propagate to other units' phases.

When a newly changed unit phase is downloaded, the execution of any unit module that contains that unit phase is not impacted AS LONG AS that unit phase IS NOT ACTIVE. When the phase is updated and if the phase is Always in Memory, the phase is instantiated. Otherwise, the next time the unit phase is required, the new version is instantiated in memory.

In a redundant controller configuration, unit module and phase runtime data are not transferred to the standby controller before PAVAIL=YES. Therefore one should wait at least 1 minute beyond PAVAIL=YES before doing a switchover so that the standby controller is ready to take control.