A communications system which provides system operators the ability to monitor and control the flow of power in a given system.
A planned sequence of actions or steps that are followed to accomplish some operation of the system such as clearing a line, transferring a load, etc.
What are three other names for switching orders?
A unique situation where a clearance point for one crew's clearance is located within another clearance for a different crew.
A formally recognized condition of a line, line section, or equipment that has been deenergized from all potential sources of energy by opening devices in the path or the potential flow of power.
Any device, connector, or opening that is utilized to isolate the line or a piece of equipment from a potential source of power.
A clear visual air gap between the source and load terminals of a device.
Visual clearance point
Condition in which all potential sources of energy are isolated by opening devices in the path of the potential flow of power. These devices are opened, checked open, locked if possible, and tagged. Grounds are typically applied.
Condition in which the main source of energy is opened deenergizing the line or piece of equipment; however, no visual opening is provided nor are personal protective grounds installed.
Which type of clearance is specifically prohibited by some companies?
The physical attachment of an approved visible tag to or near the device that has been opened and will be utilized as a clearance point.
The task of physically installing a device through a mechanism to prevent a device from being operated.
The line or equipment has power flowing through as a result of being connected to a source of energy.
The line or equipment does not have power flowing through is since the sources of power have been disconnected.
A highly skilled and knowledgeable individual who monitors and directs the operation of the power system.
What are five other terms for a clearance?
Hold off clearance
A location from which the system operators monitor and control the system.
Independent organizations that are responsible for assuring fair and open access to use the system.
Regional Transmission Organization
The area of responsibility for an operations center.
When determining jurisdiction, what two factors are taken into account?
The physical description of the elements of the system.
The geographical area in which the system is located.
Incidents in which an error occurred when the system was being operated.
____ ____ can potentially energize a line, line section, or piece of equipment that needs to be cleared to work on.
The majority of distribution poles are between ____ and ____ foot height range.
_________ poles remain the most popular choice for pole lines.
_______ and _______ poles are being used in applications where the long-term benefits outweigh their higher initial cost.
The key element in the overhead distribution system used to reduce the voltage to a level that can be used by the customer.
In the distribution system, protective equipment consists mainly of:
Fused cutout switches
The protective equipment is designed and coordinated in a manner which distinguishes _________ from ________.
Protects the main line, dips, transformers, and other equipment from faults that occur on a tap line.
Fused cutout switches
After a line is deenergized due to a temporary fault, this device energizes the lines again to minimize outage time. In the case of a permanent fault, it will stop trying to restore power after no more than four attempts.
This device opens to separate the faulted section of line from the circuit.
Sectionalizers can be set to keep reclosers from reclosing into an underground fault because they are almost always a ________ ________.
Voltage levels can be automatically controlled out on the line with the use of ______ ______.
Voltage regulators can increase or decrease the input voltage by ____ percent.
Voltage regulators are easily identified by the _________ ________ located at the top of the unit.
A device that is connected to a phase on one end, and to the pole ground, neutral, or both on the other end. It diverts surges to ground in an attempt to protect lines and equipment.
Lightning or surge arresters
A device that introduces capacitive reactance to counteract the negative effects of inductive reactance, enabling more power to be delivered to the customer.
A device that is positioned throughout the main line that is capable of breaking load to all three phases at the same time. It can be easily distinguished by it's operating handle.
The two key classifications for the instalation of equipment in underground distribution.
Above grade or padmounted equipment
Below grade or subsurface equipment
The public prefers subsurface equipment because of improved appearances but padmounted equipment is easier to _______ and _______.
When referring to conduit, the book discusses four ways cables are buried, discuss each.
Most cables are installed in PVC conduit.
Some cables are directly buried.
Steel conduit is used for mainlines in substations or where extra protection is warranted.
A continuous one-piece conduit is extruded over the cable, or cable in conduit, which increases the efficiency of installation.
A broadly used term to classify various types of concrete, fiberglass, or composite-type housings which are used to splice or terminate cables or house equipment.
Large subsurface concrete structure that house heavy cable or equipment.
An above ground structure used to splice low voltage secondary and service conductors.
The type of distribution where it is more common to use three single-phase transformers to provide three phase service.
The type of distribution where three single-phase transformers are combined into one three-phase unit to provide a three-phase service.
A term that is used to identify a pole where there is a transition from an underground circuit to an overhead circuit.
When a utility serves a city or county, the typical arrangement to install facilities is a _______ _______.
Independent distribution circuits that come from the substation into the service area. If a permanent fault occurs, or a line needs to be cleared, there is no opportunity to restore power from another source.
Radial Circuit Design
Circuits that are connected to other circuits from the same substation. Power can be supplied from other circuits should a section of line need to be cleared.
Radial Tie Circuit Design
Circuits in metropolitan areas where the primary and secondary circuits are tied together in a grid.
Network Grid Design
A distribution circuit where service is not affected if one transformer fails, it is automatically disconnected and the load is carried by other transformers.
Network Grid Design
The distribution circuit that is the most reliable and most expensive.
Network Grid Design
The method of working on lines where lineworkers must take precautions to see that they are insulated or isolated from any flow of power that could travel through their bodies.
The method of working on lines that requires precautionary procedures to ensure that sources of energy are isolated and the line does not inadvertently become energized.
If you find a discrepancy in any maps while working in the field you should always report them to the _______ _______ and the engineering department so that changes can be made.
What are the three major objectives when clearing lines and equipment?
To assure the safety of employees clearing the lines and those who will be working on them.
To minimize the impact to reliability and capacity of the system.
To minimize the number of customers who will be out of power.
Three potential sources of energy that are typically isolated to work on lines or equipment.
Power flow from the same circuit or line.
Power flow from a different circuit or line.
Power flow from a foreign generator.
One of the most common clearance points which are typically locked in the open position. These switches are gang operated, and all phases can be visually confirmed as open. These switches can be manual hook operated, manual handle operated, or motor operated.
Clearances should not overlap or share ______ _______.
A fused or solid, hook style disconnect that is commonly used as a clearance point.
Single blade disconnect
The book gives 5 examples of common clearance points, what are they?
Single blade disconnects
Open in-line sectionalizers
A continued flow of electrons, which is not interrupted when the contacts first part.
If a device is unable to extinguish an arc, what consequences could occur?
The arc will seek a path to ground.
The arc will seek a path to phase.
The device will be destroyed.
Any combination of or all of the above.
Why do capacitors improve the efficiency of a circuit?
They reduce the flow of power that does not perform any useful function.
Where would you typically expect to find a lightning arrester in a circuit?
On a transformer pole
Other poles with equipment mounted on them
How is jurisdiction normally established?
By the ownership of the system.
What do Regional Transmission Organizations typically have jurisdiction over?
Major bulk power transmission and generation elements.
System Operations Centers are a central point for any associated incoming and outgoing communications, including _____, ______, and ______.
Extinguishing an electric arc is typically accomplished by what two methods?
Increasing the distance the arc must travel.
Cooling the arc path and replacing the ionized gas with an insulated material (gas, oil, or vacuum).
In regards to a transformer, what does CSP stand for?
Completely Self Protected
On a CSP transformer, what does the secondary circuit breaker do?
It de-energizes the secondary bushings, and only the secondary bushings.
How is a CSP transformer different from a conventional transformer?
The CSP transformer has a lightning arrester attached to it, it has an internal current limiting fuse, and a secondary circuit breaker. The conventional transformer relies on external fused cutout switches and LA's.
What is the most widely used piece of equipment in the distribution system?
What are three types of single blade cutout switches?
Fused cutout switches
Load break cutout switches
Solid blade cutout switches
What causes a fuse to blow?
Excessive amperage creates heat.
What conditions must be known to control the flow of power from the generator to the customer?
Which lines and equipment are energized and de-energized.
How much power is flowing through the system, where is it coming from and going.
What is the voltage and load at certain key points in the system.
How much power will be needed to meet the system load.
The frequency of the system.
A clearance where people will not be working on the line.
A clearance where people will be working on the line.
An insulated link that is spanned with a jumper, often referred to as a "flying bell" or "span open."
Open in-line sectionalizer
Underground construction is generally _____ times more expensive per mile than overhead.
What is underground distribution immune from?
What combination of equipment is commonly place in a pad-mounted equipment case to help increase the reliability of the circuit?
Switches and fuses.
Pole lines must be designed for the proper strength and clearances for all utilities as required by the _____?
National Electric Safety Code
What are the two most common 3-phase low voltages used in the Network Grid Design?
120/208 and 277/480 volts
What does OSHA require regarding tagging?
All known sources of electrical power must be opened (switches, jumpers, taps, etc.), locked if they can be, and tagged.
Any automatic or remote controls must be tagged at the point of control and the remote or automatic function must be disabled if possible.
Does OSHA require a visual open clearance?
No but most companies to.
In regards to the impact of clearing lines and equipment, what are the two major types of clearances?
Where there is no load that needs to be transferred or the customer is shut down.
When the load going through a line or equipment must be transferred from another source.