wEek 10 !

On 2nd till 14th June we have been transferred at substaton department under Pn.Rosilawati bt.Hussin.A few days here we learn some new things.We have been explain about :

There are 3 main compartments of a substation. They are:
a) Transformer
b) Switchgear
c) Low voltage distribution board (LVDB) or feeder pillar

I have explain a lot about transformer and feeder pillar in my previous blog.So I would like to explain about switchgear.Function of switchgear;
a) Received the 11kV and feed to transformer.
b) Isolate supply when it is needed

There are few types of switchgear:
a) Vacuum circuit breaker (VCB)
b) Ring main unit (RMU)
1) Oil insulated
2) Gas insulated

vacuum Circuit Breaker (VCB) Switchgear

VCB is also called vacuum insulated switchgear. In TNB, types of VCB used are TAMCO, EPE and AICHI. VCB will trip if any fault occurred. VCB is used in important substation and in a row substation. 30 V dc supply from battery bank is used to operate the relay system of VCB. Normally VCB is used in Main Intake Substation (PMU).

The advantages of vacuum circuit breakers are:
a) Long life with minimum maintenance.
b) Compact, completely closed and sealed construction and can be used any orientation.
c) Extremely short and consistent arcing and total break times.
d) No fire risk and noise.
e) Suitable for very fast auto re-close as very little mechanical energy is required to operate them because of the much smaller contact separation.

Our new department
all the trainees and a "lecturer wanabe" :)

complete battery charger for the vcb ( vacuum circuit breaker )

8Th aNd 9tH WeeK*

Tn.Haji Mazlan b.Ibrahim asked us to read this book to understand the whole process about planning and construction department.

Next department is Planning and Construction department under Tn.Haji Mazlan b.Ibrahim. We have been placed in the office at the head quarters.

Tn.Haji Mazlan b.Ibrahim is a very busy man and he always working outside and we can't follow him because he might back late.But he give us a very useful book to study..:)

PLANNING department need to do the estimation.
Estimation involves working out the cost of following:
a) Land
b) Salaries
c) Materials
d) Contract
e) Transportation
f) Overhead

Planning involves few steps:

1.Acquiring site plan
Site plan are essential for planning as well as for MWCS or CWA form
For minor works, sketching is enough
For major project, plan is compulsory with scale

2.Making a site visit
From site visit, estimator can obtained things that need for the project such as sources of supply, types of load used and site information especially the actual situation consists of trees, type of land and telephone lines.

3.Spot the pole position
Maximum spun length
The clearance that have been standardize by TNB

4.Determine the size of conductor
Initial load and load in future
Current carrying capacity
Voltage drop – the standardize voltage range from 216V to 252V for neutral to phase and 373V to 433V for phase to phase voltage.



The voltage drop given by formula:
% volt drop = √3 I(R cos Ө + X sin Ө)
Line voltage
Where; I = line current
R = line resistance
X = line reactance
5.Positioning stay
Position of stay can be determined due to position of spun

6.Positioning section fuse
Set up to avoid probability of overload and as protection
Installation due to operation and possibility feedback

ESTIMATING MATERIAL
After planning the whole low voltage overhead line system, the materials required can be easily to determine. For minor work, the materials is tabulated at the back of MWCS and in case of major projects, the listing of material is tabulated in schedule E.

ESTIMATING SALARIES
First step involved is to determined the days that the workers should finish their work. For the example the low voltage unit can erect 2 spun in a day, therefore to erect 10 spun need 5 days. The salaries of the people who are involved such as labor, technician, foreman, technical assistance and engineer will be estimated due to days required and the salary is tabulated in schedule D.


ESTIMATING TRANSPORTATION
The cost of transportation is estimated due to distance from yard to site of project. It is also depend to the number of strips throughout the entire project. It is tabulate in schedule G.

ESTIMATING CONTRACT WORK
Estimates for contract work are tabulated in schedule F.

We get this information from the book which we find very useful and help us a lot to complete our report. We grab the opportunity to complete our log book, report and video while we working in the office. Luckily our officemates is very kind and help us a lot!

weEk 7~

During week 7,we followed the substation department which is suppposed in week 9,after the planning department. We can't joint the service department because of some problems. Fortunately the substation department have a big lorry where many trainees can also joint them. This department took some time to finish their work. We also experienced working till midnite.

As I already mention on my previous blog,there are some types of substation:
a) Indoor substation
b) Outdoor substation
c) Pole mounted substation (H-pole)
d) Package or Compact substation

This week we have the opportunity to see how they construct the H-pole (pole mounted substation). H-pole located with transformer mounted on a 2-pole or 4-pole structure in rural area where the load density is low. When a single transformer is mounted on a pole, the transformer is either secured directly to the pole or supported by a separate mounting bracket. The separate mounting bracket is widely used because the transformer can be easily removed for replacing and servicing. The maximum capacity is 300 kVA.

There are 3 main compartments of a substation. They are:
a) Transformer
b) Switchgear
c) Low voltage distribution board (LVDB) or feeder pillar

I will explain the detail at week 9, during the substation department.

we check if there is current at the feedar pillar .

H-pole

P/E Kg.Mulong

we face some difficulties during the construction. They need to cooperate with each other in order to complete the task!

6tH weEk!

Next department is service department. We met Pn.Sharinee bt. Mamat who work as the coordinator. She kindly explained to us about this department.She told us that our time table a bit weird because we should follow service department before meter department.But we told her that we just follow the timetable given. She briefly explained that Service Unit responsible is to provide the service line from low voltage overhead line (SAVR) to house (meter board). Low voltage services are line (usually insulated) that tap off from main low voltage line to feed one customer or group of customer.


sizes of overhead used in service unit department are:

a) 3 x 16 mm2 + 25 mm2 for 3 phase meter
b) 1 x 16 mm2 + 25 mm2 for 1 phase meter


The equipments used are:
a) J-hook
b) Suspension clamp
c) Dead end clamp
d) Insulator piercing connector (IPC)
e) End tube

>J-hook is made from galvanize steel. It is use to detain and support the suspension clamp and the dead end clamp.

>Suspension clamp is suitable for neutral without damaging the insulator at the suspension clamp. This clamp is set up at direct pole and angle pole that not exceeded 30˚. If so the dead end is used. Suspension clamp is needed to support the wire service too long and used more than one spun pole.

>Dead end clamp suitable for the termination pole, section pole and the angle pole which is the angle exceeded 30˚. The size of dead end clamp also depends on neutral wire (25 mm2).

>IPC is used to connect the electric supply from the low voltage overhead line (SAVR) to service line. This connector used to make sure the continuity of supply between the main line (Main) and the tee-off (Tap)

>End tube is used for covering up the conductor that exposed at the end. It is made from EPDM material that can detained very high density weather

a view before the cable connection

TNB's workers try to complete the service part.

this is IPC.

this is phase rotator. The function are:
· Used for check the phasing of the three-phase connection.
· Connect the three wires (Red, Yellow and Blue) to the cut-out according to its phase.There are 3 cut-out for three-phase supply.
· The phase rotator will rotate in clockwise if the connection is correct.

the villagers called for help because they don't receive electricity.So we check the connection .

the "person who work under contract" did not put the cable the way it should be.This is the reason why the villagers didn't get the electricity.

We can not follow the workers under service department frequently because they have only one group.The van is also small and we don't have much space to follow them.But once we follow them, we used the opportunity to learn soo many things from them...:)

wEek 5^^

at week 5, we still under metering department.we learn a lot from the technicians.In a day, we need to go to many places to put on the meter.But, if we need to use CT meters, we usually take some time to complete the task.So we usually use the whole day at the same place.The workers there explained to us about the location meter.The meter board, which accommodates the TNB’s service cut out, meters and other auxiliary equipment, shall as far as is practicable be located in such a way that it is easily accessible by TNB personnel.
The meter position for terrace house, semi detaches and bungalows in urban area should be at the entrance gate. For flats and condominium the meter should be group together. For low cost terrace house and in rural residential the meter board should be placed on / near the electric poles.


For shop house and other commercial terrace buildings (< 4 storey) the meter should be place on the pillar in front of the premises. For group of commercial lots in a shopping complex the meter should be grouped together (can be a few groups depend on the number of lots).
For low voltage industries, the meter should be located in a special partition in the switch room. Only TNB personal can access to it.In majority cases, the height of the meter board shall be such that the meter is about 1.8 meters above ground level. For other cases, the location of meter board must first be referred to TNB and approved by them.

The devices at meter board are:
a) Neutral link
b) Cut out
c) Meter

i will explained more about this in the final report...:)