1

Reduction in Downtime via Interlocking

Date: 3rd March 2012

A tripping occurred since the Areva panels had a tripping command system if the DC supply failed.

This was removed by removing that function from the panel and a alarm using a contractor with a reset operation was made

For future purposes a downtime of 60 minutes was avoided.

2

How did the failure happen?DC Input to the battery charger

failed

The auxiliary to the Panels was now

supplied by Battery storage

No DC failure sign was indicated

The Charge at Battery tank finished

after sometime

There was now no DC supply to the

panels

The Master relay of Areva Panels

Tripped since the battery voltage was

reduced

Incomer no. 3 and Unit 5 (south)

tripped

Load now concentrated only

on Dhaula

Bus coupler Tripped due to interlocking

to avoid overloading of Dhaula power

There was no supply to Unit 1, 2, 5 (south) and

Gyaanpeeth

While Unit 3, Unit 4 and Unit-5(North) operated normally

on Dhaula

3

K1 (N.C.)

Push Button (N.O)

K2 (N.O.)

a1 b1

g h

K2

K1

MCB Output

Fed byUPS Power

Hooter

SLD of the Hooter Circuit

K1 (N.C.) K2 (N.C.)

e f e1 f1

Fed byUPS Power

4

Load loss per hour 70,000INR

Breakdown on transmission line will create breakdown for hours:

60minutes

Total savings 70,000.00INR

Savings Calculations

Now if the DC fails the Hooter will show the fault.

There is also a ‘Reset Button’ to accept the fault and bring it back to normal condition.

This is not a one time saving it is applicable for the future also.

Now Downtime of Unit 1, 2, 5 and Gyaanpeeth from DC failure can be avoided.

Hooter would run and action can be taken in time.

*This is not a one time saving. For future there will be no downtime due to this reason.