Voltage Drop Course Outline

 


In column 4 type of questions is denoted by: C requires calculations, T  covers Text, G covers an illustration

 

Test

Test

Subject

Type

Topic Description

20 minutes

Test 1

 

 

 

 

1.1

voltage drop

T

Why voltage drop is important

 

1.2

energy

T

Energy Savings by decreasing voltage drop

 

1.3

required vd

T

Article 647 sensitive electronic equipment

 

1.4

required vd

T

Article 695 for fire pumps and controllers

 

1.5

required vd

T

Energy code

 

1.6

Methods

T

Four methods listed

 

1.7

reducing vd

T

Methods given for reducing vd

 

1.8

VD flow chart

G

Voltage Drop method flow chart shown

 

1.9

Table flow chart

G

Methods shown in a Table

 

1.10

Reading Table 8

G

Finding resistance for copper stranded conductors using Table 8

20 minutes

Test 2

 

 

 

 

2.1

Reading Table 8

G

Finding resistance for copper stranded conductors using Table 9

 

2.2

VD equations for Table 8

T

Different VD equations presented.

 

2.3

vd Calc simple two wire circuit

C

VD calculation using resistance from Table 8

 

2.4

3-ph vd calc

C

3-ph vd, 3 wire calc using Table 8

 

2.5

3-ph, 4-w vd calc

C

3-ph, 4 wire calc using Table 8

 

2.6

sq rt 3 multiplier

C

reason for same VD percent discussed

 

2.7

calc size of cond

C

Table 8 values used to find size in single phase 3 wire circuit for given vd

 

2.8

calc size for vd

C

Table 8 values used to find size in three phase 3 wire circuit for given vd

 

2.9

calc maximum length C Table 8 values used to find maximum length in single phase 3 wire circuit for given vd
 

2.10

calc maximum length

C

Table 8 values used to find maximum length in three phase 3 wire circuit for given vd

20 minutes

Test 3

 

 

 

 

3.1

Table 8 summary

T

Equations for finding VD, RDC, and L are reviewed

 

3.2

Skin effect

T

Skin effect discussed as it applies to larger size conductors

 

3.3

Rdc, Rac, and Z compared

G

Rdc, Rac, and Z compared for smaller wire sizes

 

3.4

Rdc, Rac, and Z compared

G

Rdc, Rac, and Z compared for larger wire sizes

 

3.5

Using Rac from Table 9

T

Equations for using Rac to find VD, Rac, and Length are shown

 

3.6

Table 9

G

Reading values from Table 9

 

3.7

Table 9

G

More on reading Table 9

 

3.8

Table 9

G

More on reading Table 9

 

3.9

Vd calc using Table 9

C

Vd calculation for 3 phase 3 wire circuit

 

3.10

Finding conductor size C Using Table 9 to find conductor size

20 minutes

Test 4

 

 

 

 

4.1

Find Length

C

Find maximum length in 3 phase, 3 wire circuit using Table 9

 

4.2

Power Factor

T

Power factor and how it effects voltage drop discussed

 

4.3

Rdc, Rac, Z compared

G

Graphic comparison of Rdc, Rac, and Z for smaller wire sizes at power factor equal to 0.85

 

4.4

Rdc, Rac, Z compared

G

Graphic comparison of Rdc, Rac, and Z for larger wire sizes at power factor equal to 0.85

 

4.5

Impedance and Rdc

G

Impedance compared to DC Resistance using graph

 

4.6

Impedance at pf 0.95

G

Graph showing how Impedance takes sudden increase for pf = 0.95

 

4.7

Calculating VD using  Table 9

 T

VD using impedance equation from Table 9

 

4.8

Using Table 9 impedance equation

T

Detailed look at impedance equation

 

4.9

Using Table 9 impedance equation

 T

More Detailed look at impedance equation

 

4.10

Sine and Cosine

G

Review of Sine and Cosine

20 minutes

Test 5

 

 

 

 

5.1

power factor

G

Review of lagging power factor as it relates to the angle of out of phase relationship between current and voltage, Cosine and arccosine reviewed

 

5.2

Table 9

G

Detailed look at reading Table 9

 

5.3

Finding arcosine

G

How to find arccosine using a calculator

 

5.4

Finding Sine

G

How to find sine using a calculator

 

5.5

VD calc with pf

C

Voltage Drop calculation for 3 phase three wire circuit with low power factor

 

5.6

VD calc with pf

C

Another Voltage Drop calculation for 3 phase three wire circuit with low power factor

 

5.7

VD calc with pf solution

C

Solution to  Voltage Drop calculation for 3 phase three wire circuit with low power factor

 

5.8

K equation

T

K equation factors discussed

 

5.9

Finding exact K

T

Using Table 8 to find exact K

 

5.10

Length and CMA solutions

T

using the K equation to find length and CMA areas

20 minutes

Test 6

 

 

 

 

6.1

Using Nm paper to calculate K

T

Discussion of Nm paper and how it describes K

 

6.2

Graph of K from NM papaer

G

Graphic of of NM values

 

6.3

Calculating K from NM

T

Using NM values and point slope equation form analytic geometry to calculate K

 

6.4

Finding VD for 3 phase four wire system when load is unbalanced

T

Finding the neutral current

 

6.5

Finding neutral current mathematically

G

Using sins and cosines in distance equation for finding neutral current

 

6.6

Review of vectors

G

Vector introduced for finding neutral current

 

6.7

Adding Vectors

G

Vector addition shown graphically

 

6.8

Adding 3-ph vectors - balanced

G

Vector addition shown graphically for balanced three phase system

 

6.9

Adding 3-ph vectors - unbalanced

G

Vector addition shown graphically for balanced three phase system in unbalanced three phase system then finding neutral current

 

6.10

VD on three phase unbalanced system T Mathematical calculation for voltage drop on unbalanced system

20 minutes

Test 7

     
 

7.1

Balancing loads to improve vd

T

Example discussed that shows balancing load can improve voltage drop

 

7.2

VD calculation with K equation

C

K equation used for three phase circuit

 

7.3

Max length using K equation

C

Maxim one way circuit length found using K equation for 3 phase system

 

7.4

Q factor

N

Q factor discussed for adjusting for skin effect

 

7.5

Segmented voltage drop

G

3 phase 4 wire where neutral is current carrying although load is balanced

 

7.6

Segmented voltage drop

C

3 phase 4 wire where neutral is current carrying although load is balanced solved

 

7.7

Segmented voltage drop

C

More 3 phase 4 wire where neutral is current carrying although load is balanced solved

 

7.8

Segmented voltage drop

C

Solution is checked

 

7.9

Segmented voltage drop

T

Segmented voltage drop as applied to Recreational vehicle parks

 

7.10

RV park Segmented voltage drop

G

Problem laid out

20 minutes

Test 8

 

8.1

RV park feeder vd

C

RV park feeder vd problem is set up

 

8.2

RV park feeder vd

C

More on RV park feeder vd problem is set up

 

8.3

RV park feeder vd

C

More on RV park feeder vd problem is set up

 

8.4

Temperature

T

Table B 310 introduced from Annex B.

 

8.5

Using NM to find conductor temperature

T

Using NM to calculate temperature of conductor

 

8.6

Using NM to find conductor temperature

T

Using NM to calculate temperature of conductor

 

8.7

Using NM to find conductor temperature

T/C

Using NM to calculate temperature of conductor

 

8.8

Using NM to find conductor temperature

T/C

Using NM to calculate temperature of conductor

 

8.9

Using NM to find conductor temperature

T/C

Using NM to calculate temperature of conductor

 

8.10

Using NM to find to find a lower cost 

T

Using NM to calculate temperature of conductor and using the reduced value of resistance to lower costs for an R/V feeder.

20 minutes

Test 9

 

 

 

 

9.1

Using NM to find to find a lower cost 

C

Using NM to calculate temperature of conductor and using the reduced value of resistance to lower costs for an R/V feeder.

 

9.2

R/V feeder cost savings

G

Actual cost saving numbers shown

 

9.3

Informative Annex B caution

T

Caution given about using informative annex B - Engineering supervision requirement.

 

9.4

VD for 1 ph 3 wire unbalanced load

C

VD Calculation for single phase 3 wire where load is not balanced

 

9.5

VD for 1 ph 3 wire unbalanced load

C

VD Calculation for single phase 3 wire where load is not balanced

 

9.6

Power factor for motor circuits

C/G

Estimating power factor for motor circuits

 

9.7

Center of Load

C/G

How to find the center of load for a circuit

 

9.8

CMA

T

Explanation of Circular Mil Area

 

9.9

Finding CMA in Table 8

G

How to find CMA in Table 8 of Chapter 9 of the NEC

 

9.10

Dividing by CMA

T

Explanation of inverse proportion relationship between CMA and resistance

20 minutes

Test 10

     
 

10.1

CMA

G

Details of circular mil area and circular mil ohm per foot resistance

 

10.2

Temperature vs resistance

 

G

Circular mil ohm resistance of copper shown in graph

 

10.3

One way circuit length

G

Details of one way circuit length

 

10.4

One way circuit length

C

VD calculation showing how one way circuit length is a factor

 

10.5

Balanced Load

G

Discussion of balanced load

 

10.6

Percentage Voltage Drop

T

How to calculate percent of voltage drop

 

10.7

Find percent of source voltage

T

How to calculate percent of source voltage

 

10.8

vd calculation two wire

C

Voltage drop calculation for two wire circuit

 

10.9

Maximum length calc

C

Calculation of maximum length for two wire circuit

 

10.10

vd calculation two wire

C

Voltage drop calculation for two wire circuit

20 minutes

Test 11

 

 

 

 

11.1

VD calculation

C

16 part calculation for voltage drop using impedance equation from Table 9 for three phase three wire PF = 0.9

 

11.2

VD calculation

C

16 part calculation for voltage drop using impedance equation from Table 9 for three phase three wire PF = 0.75

 

11.3

VD calculation

C

Finding maximum length for Table 9 calculation using embedded computer program

 

11.4

VD calculation

C

Three simultaneous voltage drops are found using the embedded computer program.