Chapter 1: Working on Lines and Equipment - Working on the Line - Key Terms - WEEK 6

Question 1

Air Switch:

Answer 1

Air switches are gang-operated, which means the moving parts are connected so that all three phases operate simultaneously with one action by the operator. Air switches may be operated by a manual hook, manual handle, or motor.

Question 2

Backfeed:

Answer 2

When current travels backward through a conductor. For example, a customer’s generator may produce backfeed (voltage) on a de-energized line.

Question 3

Capacitance:

Answer 3

When a piece of equipment retains an electrical charge after being disconnected. See also abnormal energy.

Question 4

Clearance:

Answer 4

A line, line section, or piece of equipment that has been disconnected from all normal sources of energy

Question 5

Clearance Holder:

Answer 5

The individual responsible for managing a clearance and conducting the work performed under that clearance. The clearance holder works under the direction of the system operator

Question 6

Clearance Point:

Answer 6

Any device used to disconnect a line or equipment from the normal flow of energy. These include switches, disconnects, jumpers, connectors, terminations, and other devices. See also non-visual clearance and visual clearance.

Question 7

De-energized:

Answer 7

The point at which all supply conductors have been tested to verify the absence of nominal voltage, and then shunted together through the grounding process so that all supply conductors share the same potential as the earth.

Question 8

Disconnected:

Answer 8

Disconnect the lines and equipment from all normal sources of energy: all connections have been opened, locked, and tagged. At this point, the line is disconnected but not yet de-energized.

Question 9

Energized:

Answer 9

Specific sources of energy (such as a generator) that could energize a line, line section, or piece of equipment that needs to be cleared. See also normal energy and abnormal energy

Question 10

Fault Current:

Answer 10

The amount of current that a given system can deliver to a short circuit, also known as a fault. Protective grounds must be rated for the available fault current.

Question 11

Field Operator:

Answer 11

Any employee in the field who is physically operating equipment. This may be a lineworker, crew leader, troubleman, switchman, roving operator, station operator, or other employee.

Question 12

Flying Bells:

Answer 12

Also known as a span open, this type of clearance point can be installed at various locations to minimize the number of customers who will be out of service.

Question 13

Induction:

Answer 13

A process by which a disconnected or de-energized conductor becomes electrified through the magnetic field of a nearby energized source. Also known as induced voltage. See also abnormal energy.

Question 14

Line Recloser:

Answer 14

Line reclosers are widely used as clearance points. In addition to the line recloser being open, most companies require a separate clearance point in the form of open jumpers, disconnects, or air switches.

Question 15

Lockout:

Answer 15

Physically securing a locking mechanism (such as a padlock) to a disconnecting means in order to prevent the device from being operated.

Question 16

Non-Visual Clearance Point:

Answer 16

An enclosed clearance point that is not visible from outside of the enclosure. See also clearance point and visual clearance.

Question 17

Open Jumper:

Answer 17

Used on both primary and secondary circuits, open jumpers, open loops, and open taps are common clearance points. (A jumper is a piece of conductor used to complete an electrical circuit.)

Question 18

Protective Grounds:

Answer 18

Protective grounding cables come in different sizes to protect against different levels of fault current. All must have a current-carrying capacity equal to or greater than #2 AWG copper. The higher the fault current, the larger the grounding conductors and components must be. For example, #2 AWG copper is nowhere near adequate for the fault current levels on a 500,000V transmission line. Remember: when speaking of fault current, size matters.

Question 19

Single-blade Disconnect:

Answer 19

Many types of disconnects are used as clearance points-for both line and substation clearances. Some are designed to interrupt normal line current, while others require a special tool to interrupt the current when opening.

Question 20

Step Potential:

Answer 20

A voltage drop between a worker’s feet when the ground is energized by fault current. The difference in potential can cause current to flow through the lower body. Step potential is greater the closer the worker is to the point that the fault current enters the ground. See also touch potential. stringing block ground - A device that grounds conductors as they are being installed. Unlike a running ground, stringing block grounds are installed at various locations along the path of the wire stringing. See also running ground.

Question 21

System Operator:

Answer 21

A utility employee who has a system-wide perspective of the electric grid. A system operator evaluates clearance requests and issues clearances to workers in the field.

Question 22

Tagout:

Answer 22

1.2.7 (LOCKOUT-TAGOUT PROCEDURES) OSHA requires all devices that are used as a clearance point-such as switches, disconnects, and jumpers-to be opened in order to disconnect the sources of energy. Make these devices inoperable (if their design permits it) and then clearly tag them to indicate that employees are at work.

Question 23

Touch Potential:

Answer 23

A voltage drop between an energized metallic object that a lineworker is touching and the place where a worker is standing. See also step potential.

Question 24

Visual Clearance Point:

Answer 24

A clearance point that has a clearly visible air gap between the source and load terminals of a device. See also clearance point and non-visual clearance.