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29/01/2020 at 15:50 #427
Ppe
must be of correct insulating class
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- electrically insulating safety helmet
- insulating rubber gloves
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must satisfy international IEC standards, subjected to dielectrical, mechanical resistance and ageing test.to check if easily broken
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- Insulating gloves
- Pneumatic glove tester,
- Insulating boots
- Insulation mat
- Face shield, safety glasses, arc protective hood
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High voltage operation procedure
Electrical permit to work, earthing down, circuit earthing, and bus bar earthing.
Circuit earthing – feeder cable connected by earth connection to all 3 conductors. This is done at circuit breaker using a key, circuit breaker cannot be on unless earth has been remove.
Bus bar earthing, when It is required to work on busbar, they must be isolated from all possible electrical sources and earth using portable leads.
Follow high voltage check list.
DIE- disconnect, isolate, earthing
Earthing down to ensure any stored electrical energy stored is safety discharged to earth
Electrical permit to work
- To issue before start of work, to include description, declare the isolation and earth down, ensure it is safe to work by authorizing officer, permit to cancel after job.
- in the switch room, check for the 6 items
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- danger sign at the front door
- single line diagram, authorized
- rubber mat covering entire length of switchboard
- fire extinguisher mark C
- first aid chart
- electrical installation license
- key box
- logbook
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- wear the correct PPE
- separate the work area from source of power supply by
- isolate
- lockout & tag out
4) Check the absence of voltage (prove dead) at source and on site, on each conductor involve. Using appropriate type of voltage detector which are verified working.
- all exposed conductor must be treated as live unless proven dead, hence to be kept a distance.
5)apply short circuit and earth systems
- discharge residual voltage
- apply safety earthing leads
6) Show and warn others and limit of work area.
7) Issue permit to work to work in charge and paste notice against any interference on equipment that you are working on.
8)where work is carried out on high voltage not under control of authorize LEW, LEW to arrange a cert from the person having control of the electrical supply
ISOLATION OF TRANSFORMER
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- get necessary aspprovals to work on system
- open the circuit breaker in high voltage system
- set the circuit breaker in hvs for isolated
- use earth switch in hvs to ground cable
- a key in ground switch panel will release
- place warnings signs on the front on High voltage system
- use key from HVS to access room transformer placed
- make sure transformer not under voltage
- use mobile grounding device to each phase of transformer
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