Haliade-X High Voltage AT2 Familiarization Flashcards

Collection of vocabulary terms and definitions regarding high voltage safety, equipment, and roles for the Haliade-X Haliade-X High Voltage AT2 Familiarization.

High Voltage (HV) Switchgear

Under the GE Vernova OFW ESP, this is identified as any switchgear operating at voltages above $1000\,V\,AC$ and $1500\,V\,DC$.

AT2 (Authorised Technician 2)

The individual responsible for checking RAMS, ensuring safety documents are robust, delivering turbine pre-task briefings, and maintaining safety precautions during work.

Safety Document Issuing Authority

Responsible for establishing HV isolations/earthing, issuing AE2 pre-written safety documents, and verifying equipment is safe to return to service.

AE2 (Authorised Engineer 2)

Responsible for risk assessments justifying live testing, approving HV safety documents, and maintaining a list of safety documents for each site.

ROC 1 (Remote Operation Center Role 1)

Responsible for safely operating HV equipment from the ROC for functional switching or to achieve safety from the system as instructed by an AT2.

ROC 2 (Remote Operation Center Role 2)

Includes all ROC 1 responsibilities plus interrogating HV systems for fault finding and operating equipment of an unoccupied turbine.

Circuit Breaker (CB)

Equipment used to make or break a circuit under fault or load conditions; categorized by insulating mediums like Air ($ACB$) or $SF_6$ ($GIS$).

Disconnector

Used to provide physical and securable separation between conductors for isolation; generally cannot be operated under load.

Three-Position Disconnector

A device on the Haliade-X that can be in three states: Closed/Earth Open, Open/Earth Open, or Open/Earth Closed ($Q11$ or $Q51$).

Disconnecting Circuit Breaker (DCB)

A circuit breaker that also provides enough physical separation between contacts to be rated as a Point of Isolation ($PoI$).

$$Q01$$

The primary HV disconnecting circuit breaker found in the $GIS$ used for main circuit protection and isolating the $66\,kV$ supply.

Earth Switch

A device used to create a short circuit to earth to bring equipment to ground potential for safe access.

Primary Earth

An earth of suitable cross-sectional area to withstand inadvertent energisation for $2\,seconds$ until fault protection operates.

Drain Earth

A fixed or portable device applied to protect against induced voltages, impressed voltages, or inadvertent back-feed.

$$F650$$

The primary High Voltage protection relay on the Haliade-X providing protection against over/under voltage, frequency, earth faults, and over currents.

Instantaneous Overcurrent Protection

Protection where the relay operates as soon as current exceeds a preset value with no intentional time delay.

Inverse Time Protection

Protection where the operating time is inversely related to current; higher currents result in faster relay operation.

Main Transformer

A transformer on the Haliade-X rated at $66\,kV / 3.1\,kV / 3.1\,kV$ using Oil as an insulating medium.

Service Voltage Transformer ($T6$)

A transformer used to step down voltage from $66\,kV$ to $400\,V$, insulated with $SF_6$.

Functional Switching

Switching actions specifically aimed at returning a turbine to service or preventing a nuisance trip.

Safety Switching

Switching actions aimed at isolating and earthing equipment to make it safe for access, testing, or work.

Nuisance Tripping

The potential to inadvertently trigger an HV circuit breaker while working on specific LV systems.

DIESR

The HV Safety Rules acronym for: Dead, Isolate, Earth, Screen, and Release.

Permit to Work (PtW)

A formal, written safety document authorizing work on equipment that has been isolated, de-energized, and earthed.

Sanction for Test (SfT)

A document authorizing HV testing activities on equipment that may be live or not fully earthed; required for test voltages above $5000\,V$.

Limitation of Access (LoA)

A document issued for limited access to HV areas for non-electrical work under conditions not involving live conductors.

Interlock

A mechanical, electrical, or software feature that makes the state of two mechanisms mutually dependent to prevent unsafe operations.

Gas Densimeter

A device used to permanently monitor $SF_6$ gas density in the switchgear and trigger alarms for pressure decline.

$GDM$ (Generator Disconnector Module)

A motorized 3-phase disconnector used to connect, disconnect, or ground the generator.

Turbine Island Mode (TIM)

A feature that allows the turbine to generate power in island mode to supply its own auxiliary systems during prolonged grid loss.