CU Suspension

This process is used to suspend the controllable unit (CU) temporarily.

The suspension is valid for the following combination:

• controllable unit - the CU that is suspended.
• impacted system operator- the one that suspends.

All procuring system operators will be affected by the suspension as the CU will no longer be approved to deliver services. Procuring system operators and impacted system operators will receive notification of the suspension.

Changes in CU data is handled by the CU Update process. If there are significant changes in CU data or the data is incorrect, the CSO can perform a new grid validation instead of relying on CU suspension.

If there are issues in the grid where the CU will temporarily be a threat to safe operation, then temporary limits should be used.

Suspension is a powerful tool, and it should not be the primary way to limit the use of a CU. A CU suspension will effectively prevent the CU from delivering any services to any procuring system operator. The combination of temporary limits and new grid validation status should be sufficient to ensure safe operation. Consequently, CU suspension should not be neccessary unless there is an extraordinary case. Rather than serving as a primary solution, CU suspension functions as a safety valve for extraordinary cases.

Reasons for suspension:

Reason	Description
compromises_safe_operation	Delivery of services from the CU might compromise the safe operation of the ISOs grid.
other	Should generally not be used, but can in cases where ISO has a valid reason for suspension.

The process also includes reinstatement of the controllable unit, i.e. removing the suspension.

Prerequisites

• The issue that triggers the suspension is temporary.

Sequence

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