Questions Flashcards
(24 cards)
Reasonably practicable
Balance of risk against cost, risk assessment , control measures
Define Isolation
Disconnection and separation from every source of electrical energy in such a way that the disconnection and separation is secure
Where on the body is the point of highest electrical resistance
Dry skin
If your proving unit fails what can you do?
Get another unit or do not carry on
How is access to switch rooms controlled?
By locking the rooms at all times and only allowing authorised persons to be issued with the keys
What should you do before proving dead
Visual checks of potential indicator
How do you isolate HV and LV supplies?
HV - Circuit main earths shall be applied at all points of isolation
LV - points of isolation shall be locked open
What happens to a Permit to Work when the recipient is unavailable?
A new PTW shall be issued to the person who is to continue the work. An authorised person shall cancel the original permit and inform the holder of the original PTW that their PTW has been cancelled and that the apparatus is to be considered live
Secure
Remove
Apply
Remove
Isolate (opposite)
Restore
Open
Close
Who would normally apply additional earths?
The competent person at the point of work
Is it permitted to carry out work on an HV circuit without a CME being applied
No
Potential indicator checks
Check rating and condition, check operation before and after, ensure approved and used by AP
Smell of rotten eggs in substation ?
Report, lock doors, exit area
Bus bar are shutters not closed?
Lock door, report
Vertical isolatable circuit breakers - what are the 3 service positions?
Bus bar earth, service, circuit earth
Why do we use anti-reflex handles?
To stop us from reversing an action quickly
Name 3 things a protection system does
Detect a fault at the lowest possible current
MINIMISE - disconnect the faulty plant in the shortest possible time
DISCRIMINATION - disconnect only the affected equipment to leave as much healthy equipment in service
What is fault energy proportional to?
I2t
What are the 2 main causes of excess current?
Short circuit
Overload
Where do you find a Buchholz relay
Oil filled transformer
5 deadly sins?
Proving dead (earthing) Application/security of earths Identification of equipment Safety lock procedure Proving dead at point of work
