AT2 OJT Questions Flashcards
Study AT2 OJT Exam
What is classed as high voltage in the ESP?
Above 1000VAC and 1500VDC
What are the main dangers to individuals as a result of HV switching?
- Arc Flash
- Arc Blast
- Electric Shock
In order to provide safety from the system when carrying out High Voltage work under the ESP. What documents would you require?
- AWP
- RAMS
- Work Permits
- Pre-task Brief
- MFI/LFI
What is the Pre-amble with the ROC before asking to carry out a HV switch.
- Time/Date
- Name/Position
- Site/Location
- AWP No.
- Step in the AWP
- What Equipment is being operated and to what state
What are the 5 steps to achieving General Safety?
- Safe Access and Egress. There must always be accessible entry and exit points.
- Safe Place of Work. The work area must be clean and tidy, free from obstacles and danger.
- Safe Methods of Work. Work procedures have been developed by using Risk Assessments and Method Statements and finally described in the Approved Written Procedures. The ESP rules also includes supporting procedures and management instructions.
- Safe use of Equipment. The equipment is safe to use and has been tested/calibrated. The user has been trained on how to use it.
- Personal Protective Equipment. The Technician/User wears/uses the correct PPE for the task and is also trained on how to use it.
Talk about the F650 and when it can/can not be used…
- In the LCC is the F650, a protection relay that includes the digital HMI of the module.
- When the LCC is powered, the F650 relay allows communication with SCADA.
- The F650 can be used in LOCAL or REMOTE mode when all actuators of the SWGR module are in their respective ELECTRICAL modes.
- LOCAL mode allows the SWGR operation through the F650 HMI with a hand held device.
- REMOTE mode allows the SWGR operation through the F650 HMI with SCADA.
When arriving at the SWGR, what positions would you expect the equipment to be in and why?
- All actuators in electrical mode.
- LCC in REMOTE mode.
Explain what visual inspections would be completed prior to the request of any operations?
- Ensure access to the area is safe.
- Ensure that before entering the SWGR area there are no unusual noises (crackling/buzzing), unusual smells (Rotten eggs/Decomposed SF6), unusual sights (Burns/Dust) and that the area is generally safe.
- LCC to be in remote mode when entering the WTG/SWGR.
- Voltage indicators to show that there is voltage present.
- Check Densimeters for correct level of SF6 gas. All Densimeters should be in the “Green” of the dial.
- Check that all actuators are in ELECTRICAL mode
- Check shock indicators if present, to ensure the SWGR has not been dropped or suffered any impact during installation/service.
- Ensure blast valves have not been activated.
- Ensure that the mechanical spring is charged on circuit breaker Q01.
Explain the Switching hierarchy.
The switching hierarchy is in place to ensure that switching is carried out at the furthest distance possible from the SWGR, thus completely eliminating any potential risks of Arc Flash/Blasts as the working party will not be in the vicinity of the SWGR.
The preferred order to switch is as follows…
- Remotely via ROC.
- Locally via handheld pendant, with working party and authorised technician stood on TP away from SWGR.
- Locally via HMI on SWGR.
- Manually operating SWGR circuit breakers.
Explain safe zones/safe distances?
Approach distances are to ensure persons not authorised to enter the working area remain safe. Those who are authorised to enter must meet competency requirements and make use of approved tooling, equipment and PPE.
Limited Approach Boundary: Distance that an unqualified person must maintain from the exposed live conductor.
Restricted Approach Boundary: Distance closest to the exposed live conductor that may only be entered by an authorised person under GE OFW ESP.
151 VAC - 750 VAC - Restricted Approach Boundary: 0.3m (1 ft. 0in.)
751 VAC - 15 kV - Restricted Approach Boundary: 0.7m (2 ft. 2in.)
46.1 kV - 72.5 kV - Restricted Approach Boundary: 1.0m (3 ft. 6in.)
Discuss demarcation and creating a safe test area.
- First, identification of equipment being worked on.
- Demarcation must adhere to/be at correct safety distance depending on the voltage of the equipment being tested/worked on.
- Demarcation be placed around equipment and legible throughout work - Done prior to TBT and test/work.
- Demarcation must only have one point of access/egress, which should be controlled and manned throughout testing and work.
Explain the sanction for test and talk about the primary earth/earth bar.
A Sanction for Test allows for the removal of fixed Primary Earths for testing purposes. This is carried out by an Authorised Technician in the company of another Authorised Technician who has received an approved written procedure from an AE2.
Sanction for Tests can be used to carry out tests such as Insulation resistance and cable load tests.
A primary earth is used for earthing HV equipment and placed between the point of work and all points of isolations. The earth shall be of adequate cross-sectional area between earth and the HV equipment so as to safely discharge fault current due to inadvertent energisation.
Explain the Return to Service stage and equipment status.
The return to service is the clearance of Mechanical and Electrical Isolations upon completion of the work or execution of the task. Personal padlocks will be removed from the lockbox to access keys for isolation padlocks/devices.
The AWP will be cancelled in this stage.
What is the difference between the ROMP and sanction for test?
ROMP - Restoration of Motive Power is the energising of motive power supplies of Mechanical Equipment and/or LV Equipment. This is carried out in an approved manner according to the AWP, specifying circumstances and methods of dealing with hazards that arise in this process.
The ROMP can be used for testing purposes after remedial work is carried out or for the re-positioning of the rotor if further work is needed.
A Sanction for Test is issued when working on HV Equipment when the Primary Earth is required to be removed. The Primary Earth will be removed in the circumstance where testing the HV electrical Equipment is required, for example, pressure testing HV cables.
What are the two types of supervision described in the ESP and what are the differences between them?
- Personal Supervision
- Immediate Supervision
Personal Supervision requires the Authorised Technician to be directly present with the person being supervised i.e. one on-one/over the shoulder. Immediate Supervision will mean the Authorised Technician is to be continuously available in the working area i.e. on the turbine supervising his/her working party.
When exposed High Voltage conductors are suspected of being live, what are the only objects permitted within the restricted approach boundary?
No objects should be permitted within the restricted approach boundary if there are suspected exposed HV conductors. Isolations should be in place to prevent energisation and an earth applied to dissipate any potential, and only then should GE OFW ESP approved testing device be used to test the HV conductors for dead.
