HEAT CYCLE TEST

ACTIVITY ON 6/4/10


We are not given any specific task yet..therefore i took this opportunity to ask the technician about the on going project. one of it is HEAT CYCLE TEST....

what is HEAT CYCLE TEST ??

its actually part of a test should be done in IPC (Insulation Piercing Connector) inspection...since IPC used in Malaysia don't have the standard, therefore TNBR did a research about it. the reason of it because there is a case where IPC melt and dropped on consumer's house and they claimed compensate to TNB. furtheremore, it also dangerous to the resident....

how the test look like??

Heat Cycle Test (HCT)

where can we find it in our daily life ??

it's located at the top of electrical pole

another purpose of this test are :

> to determine the contact resistance characteristic (CR)

> to check the endurance of conductor (cables)

How to conduct the test??

1) 1st of all, for sure need to setup the equipment

2) connect an IPC for every each extension (there are 5 cables overall)
3) current flow in a loop supplied by Current Transformer (two big black boxes in HCT figure)

4) connect a multimeter to the loop

since we are dealing with current, they will be heat produced

5) to monitor the temperature, they used data logger

> every 30 minutes technician will take the reading.

> we need 1 hour to complete 1 cycle, during 1 hour there will undergoes two process,

current inject and current remove. this also know as aging process.

Data Logger

actually, this is a long project since it has to complete 200 cycles

1 CR - 25 Cycles

1 Cycle - 1 Hour

1 Cable - 200 Cycles

1 Cable - 8 days

*if after 200 cycles there is no failure occure at IPC or cables, its mean the IPC suit with the cable...end of this test, only one cable left..

6) CR measurement

> Big Clamp for current measurement

> Small Clamp for voltage measurement

the design of the clamp comes with two sizes because as we know that the flow of current will

produce heat, so that it needs big size to avoid the clamp from melt. since the increasing of voltage won't gives any effect, small size is sufficient.

CR Measurement Device

as told by the technician, only current flow in the loop and zero voltage. how current will flow without voltage????

* u as engineer, u should know how to explain... ^_^

lets have a short review....

we know that current cannot flow without voltage right?? it already stated in Ohm's Law " no current without voltage V=IR ". so that, it is impossible to happen right??

now, lets engineer (wanna be) explain to you... =D

actually like this, as i mentioned before current was supplied by Current Transformer...what do you remember about transformer?? (think deep..said my boss)

this case happened because of two factors :

(1) Transformer Effects

(2) Energy

Transfromer Effecs

- depends on number of turns

- consist of two conduction modes : step up & step down

- two windings : primary & secondary winding

- Principles of Induction Faraday Law applied

- Any system in the world cannot violet the law of Physics

- only AC supply allowed to operate the Transformer

*we focused on 3 bolted point

Energy

- general info : energy cannot be create and destroy

- the energy is supplied by the CT

- main power and primary winding also provide the energy

- energy will convert to very high current with low voltage

- we know that, P = VI cos (phi)

P = constant, if I increase, V decrease (when current high, voltage yeild is very small) * usually engineer will neglect the small value

in simple explainasion, put a pinch of salt into a gallon of water won't change it taste right?? same goes to the system, if want to produce high current, we low the voltage.

* apply the right law at the right place