1 Overhead Distribution - 1 Basic Concepts 1 Overhed Distribuion Systems Flashcards
What are the main 2 systems of distribution ?
Lateral and loop system.
What are the two main voltages of CMP distribution voltage?
15KV and 19.KV
What is the Lateral system?
The Radial distribution system has one power source for a group of customers.
If there was a power failure, the entire group loses power. In addition, a circuit failure somewhere in the system could mean a power interruption for the entire system.
What is the loop system?
The loop distribution system loops through the service area and returns to the point of origin.
The strategic placement of switches permits the electric company to supply power to customers from either direction. If one power source fails, switches are opened or closed to obtain power source.
What is Network distribution system?
In Network distribution system the customer is connected to two or more sources of power, if one of the sources of power fails the customer will not lose power since he/she would have power through the other sources of power.
What is the cross arm?
The cross arm is the horizontally installed wooden Arm installed on top of the pole.
Where is wood brace for cross arm is used for?
Wood braces are placed to support cross arm structures weight.
What is side arm or ally arm?
Cross arm or ally arm is when arm is mounted to one side of the pole top.
What is Ally arm brace?
Ally arm brace is used to support cross arm or ally arms weight.
It is installed in the angle to ally arm and pole.
What is the arm less construction? Give some examples of arm less constructions.
The arm less construction is when pole has no arm installed and the wires are supported by other methods such as using fiber glass rod or vertical construction.
What is the most common type of electrical insulator material used by electrical utility’s to support primary bare wire?
porcelain insulator
What is the disk insulator?
Disk insulator are disk shaped insulators that are connected by string.
Where do we use disk insulators in electrical distribution system?
They are mostly used in dead end or where the wire is changing direction.
What is the post insulator ?
the post insulator is the calendrical insulator that is mounted flush on cross arm or pole
That supports wires.
What is the pin insulator?
The pin insulator is mounted on the pin and the pin is mounted on a pole or cross arm
What is the spool insulator?
The pull insulator is a type of insulator that is normally used to protect secondary wire and primary neutral wire. It is connected lower then primary on the pole side.
What is the guy wire?
A guy-wire, guy-line, guy-rope, or stay, also called simply a guy, is a tensioned cable designed to add stability to a free-standing structure.
What is a down guy or anchor guy?
Down guy or sometimes called anchor guy a type of guy wire where the wire Is connected to the guy anchor
What is the pole guy?
The pole guy is connected from one pole to another pole with a guy wire to support the wight of the other pole.
What is SIDEWALK GUY ?
Sidewalk guy is directed away from the pole by the strut and then connected to the anchor away from the pole
What are the arrows pointing at in the photo below regarding the pole top distribution transformer?
Answer: secondary bushing.
What is the arrow pointing at in the photo below regarding the pole top distribution transformer?
Answer: secondary bushing
What does voltage regulator do in distribution system?
Voltage regulator regulates the voltage. If the voltage drops by change of load the regulator brings the voltage
Back to the preset interval volage.
How to tell the difference between voltage regulator and voltage transformer since both are calendrical shape?
Voltage regulator has no secondary bushings, also the voltage regulator has the position indicator as shown below that no pole top transformer would have.
How do capacitors look like in pole top distribution system?
They are identified as square shaped bank of several connected to each other.
How to identify pole top reclosers in distribution system?
The single phase reclosers have 2 primary bushings and no secondary bushing, It also has an operating handle to allow manual opening and closing.
What is the sectionalizer ?
It’s a protective device that opens when it sees no power. It is usually coordinated with recloser.
A sectionalizer is an automat ed switching device that is intended to isolate faults, and is typically used in conjunction with an upstream recloser. The sectionalizer counts the number of operations of the upstream recloser to determine if the fault is temporary or permanent.
How to identify sectionalizers on pole top distribution system?
They look like single phase reclosers, a cylindrical shape with two primary bushings, open and close handle and no secondary bushing. They are mostly smaller in size then reclosers however the only way to be sure is to read the name plate on them.
Where are sectionalizers on pole top distribution system used?
They are usually used where lateral or branches of a circuits are, to isulate smaller sections.
What is a fused cut out and what does it do?
Fused cut out is a protective device that isolates part of the lateral branch of distributions system from fault .
name major parts of the cutout.
Cut out is made of insulator, two contacts , two connection points, Fuse holder, fuse inside of the fuse holder.
Name the part shown in the photo below on fuse cut out
Answer: Insulator
Name the parts shown in the photo below on fuse cut out
Answer: the contact points.
Name the parts shown in the photo below on fuse cut out
Answer: the connection points.
Name the parts shown in the photo below on fuse cut out.
Answer: Fuse holder and fuse inside of the fuse holder.
How does the fuse cut out works?
When current exceeds the limit of fuse. The fuse will melt of and spring loaded fuse holder would open.
Name the parts on the fuse cutout
- Porcelain insulator
- fuse tube
- Top Hood
- Line-end Connector
- Load-side connector
- Upper Contact
- Lower contact
- Hinge
- Pull Ring
- Attachment Hooks
What is the current limiter in distributed system?
It’s a device that limits the amount of current that goes to it and only allows a certain amount to come out of it. It is used to protect equipment from fault or short circuit conditions.
What is the surge arrester?
It’s a protective device that protects equipment form lighting or surge faults.
What is the static wire?
Static wire is installed to protect the system from lighting. It is installed in top of the pole between poles and at each pole it goes to ground. This way if lighting happens then the voltage from lighting would go to the ground and therefore it creates a safe zone for equipment on the pole top.
What are the gang operated switches?
They are used to sectionalize circuits, tie the circuits overall they are used for switching capabilities.
Name The Primary system shown in the photo below.
This is a Y system
How does the Y system works?
In the Y system equipment is connected to between Neutral and one of the three phases (A, B or C)
The Y system is typically a 4 wire system.
Name the primary system shown in the photo.
This is a Delta system.
How does the Delta system work.
A delta system typically consists of 3 wires and the equipment is connected between two of the three phases ( A, B and C)
How to tell a distinguish between 34.5KV and lower voltage systems such as 19.9KV and 7.2KV?
The first thing that you can observe is the size of the bushings insulator, 34.5KV should have the biggest bushing insulator in CMP Distribution system. This indication might not be as reliable. However if you are not sure take a look at the pole top transformer distribution bushing sizes, the 34.5KV has busing almost twice the size of 19.9kv system.
Finally the ultimate prove is to take a look at the transformers name plate. Also remember that some transformers are dule voltage such as 7.2kv and 19.9kv therefore you have to make a note of what’s the presenting of that transformer.
what does this photo mean on transformer?
On the dule voltage transformers the X between two voltages indicates that the transformer is dule volage. As shone below. This transformer has a switch that can alter between 7.2KV and 19.9KV
