ENG4216-A

Lock out / tag out is the procedure __________________________________

• To carry out maintenance jobs safely

• To keep the machines in lock forever

• To put tags with names of machine parts

• To get permission for maintenance job

Which of the following is NOT a hazard in working with a high voltage electrical transformer? 

• rotating machine

• corona effect

• oil leakage

• high voltage

Before doing maintenance work, what preparations you must do in case of fire or emergency?

• Locate nearest bathroom

• Locate the nearest first aid, fire exit and firefighting equipment

• Locate nearest mall

• Locate nearest cafeteria

A work permit is a document used to _____________. 

• Take permission to start any maintenance work

• Estimate the cost of any maintenance

• Describe the skills of the technicians doing maintenance work

• Ensure the availability of spare parts needed for maintenance

In performing DC winding resistance test, a measured value of resistance equal to zero (0) ohms, means _____________.

• shorted winding

• open winding

• good winding

• none of the choices

In performing an insulation resistance test between the winding and core of a dry-type transformer, a reading of less than 1mega-ohm insulation resistance would mean _______. 

• not good insulation between winding and core

• good insulation between winding and core

• there is water inside transformer core

• none of the choices

Insulation resistance in the transformer may vary due to ________________. It is a must to monitor it while conducting an insulation resistance testing.

• oil temperature

• oil price

• oil density

• none of the choices

In transformer core testing, if the measured magnetizing current is within 30% of the previous reading, it means ______________. 

• satisfactory reading 

• there is fault in the winding

• unsatisfactory reading - needs further analysis of the core

• none of the choices

Which of the following transformer monitoring and diagnostic teachniques that uses infrared imaging that can detect heated parts of transformer. It can detect looses connections, unbalanced loads, and faulty wiring.

• IR sensing

• vibration sensing

• gas detection

• insulation testing

Atmospheric lightning can cause transformer failure specially for outdoor transformer or substations. Which of the following correcting measures can be used to mitigate the effect of atmospheric lightning in transformer?

• Use lightning arrester

• Use overload protection

• Use Buchholz relay

• none of the choices