HT SWITCHGEAR ERECTION ,TESTING AND COMMISSIONING (PART-II) -ABC OF THERMAL POWER PLANT

In my last dispatch I have indicated the number of panels required to be installed for HT connection .A picture of the same was also attached. Numbers of panels are erected aligned on line. Incoming and outgoing cables are laid through spreader room . These panels are erected by the side of the service bay through an opening kept for this purpose only. Once these panels are and aligned then pre-commissioning activity starts.

Opening has been kept at service bay side to lift panels as shown in the above picture.

Cable spreader room  erection of cable trays under progress. This is below the Panel room

This is the panel room ..civil works under progress.

Following testing are being carried on HT panel after erection.

 a. Insulation resistance measurement of bus bar (power ,control ),vcb

b. Busbar,contact resistance measurement

c. High voltage test – bus.

d. Primary injection test  - vts & cts.

e. Protection, interlocks and metering circuits .

Following instruments (calibrated)  , systems , qualified testing personnel  ( Accident while testing is very common, this may be fatal at HT lines) etc are required to be lined up.

5000v insulation tester (motorized) ; 3 phase 415  ac 50 hz system with variac (3 ph and  1 ph)

Dc control supply (preferably from permanent DC source;  Hi pot ac/dc source

 Measurement kit ; Current injection kit ; Micro ohm meter; Milliseconds timer ; Multimeter ( 4 and half digit ) digital ; Ananlog Multimeter ; Volt and Ampere meter for measurement; Tong tester;  Number of long testing leads with end connectors ; Supplier’s tools for the panel etc.

Safety precaution is paramount before and after testing a few points are given below:-

The Engineer-In-Charge of the testing  team will inform each member of his team as to the exact nature and extent of his contribution and responsibilities towards the tests carried out.

 Only nominated person will take part in the tests. 

All persons must acquaint themselves with the use and location of fire  extinguishers and first aid posts.

Adequate lighting facilities will be provided at all times.

Each test will be carried out under the control of the test team leader.

A strict and safe method of applying test leads shall be practiced.  Bare wires shall not be inserted into sockets.

A record of any alternation made during the test such as shorts or disconnections, shall be made and annexed to relevant test procedures .

Adequate number of poster ,signboard are placed strategic location for safety.

All procedures are recorded and checked with the drawings . A single line diagram or conditions to energise the particular panel and also for tripping may be made before testing .This will be immense help. This is not a must condition but helps during testing as ready reference.

CHECKLIST FOR THE FOLLOWING PANELS ARE CHECKED

i. Incomer panels (1 & 2) ;ii. Outgoing feeders; iii. Bus coupler; iv. Tie breaker

- All incoming and outgoing cables to incomer panels are completed.

-Interlocks for closing and protection for tripping are to be checked as per standard check list.

-11KV Bus Duct/Cable erection from station switch gear to unit switch gear complete in all respects.

-The Tie Breakers at station switchgear end of tie is tested and in withdrawn position with shutters locked.

All circuit breakers contained in 11KV unit switch gear in withdrawn position.

Clearance from Erection Department for carrying out tests on 11KV unit   switchgear and 11KV Bus duct/cable from unit to station switchgear obtained.

-11KV station switchgear associated with the energising of this unit switchgear is live.

-Safety Clearance notification issued  and effective for 11KV unit switchgear and 11KV tie bus duct/cable.

-The associated DAS/Annunciation scheme is complete, tested and in service.

-The control supplies are available.

COMMISSIONING PROCEDURE :

-Check and test all the panels of 11 KV unit switch board and associated equipments as per their standard check list.  Record in a format for future use.

Check and test the unit switchgear bus bars and the Tie bus duct/cable to the station switchgear as per their standard check lists and record.

Check and test supply cables for the DC control bus and the AC heater supplies as per their connection diagram and record.

Continued to PART-III --PRE ENERGISING TESTING ,AND COMMISSIONING