EENG 80 : Electrical Apparatus and Devices
LABORATORY EXERCISE 1
DISTRIBUTION TRANSFORMER MAPPING
(Residential)
I. INTRODUCTION
A distribution transformer is the type of transformer that performs the last
voltage transformation in a distribution grid. It converts the voltage used in
the transmission lines to one suitable for household and commercial use,
typically down to 240 volts. These transformers are pole-mounted if the
transmission lines run above ground (see figure 1), and they are pad-
mounted (see figure 2) if the transmission lines lie underground, as is the
case in many suburban areas. The pad-mounted transformer is usually
green and visible on the front lawns of many homes.
II. MATERIALS
1. Google Map
2. Pens
3. Papers
4. Ruler
5. Calculator
6. Autocad for Layout
III. PROCEDURES
1. Check the Location at Google Map for your assigned Place
and make sure that you printed the whole Area including all
the Houses that are connected to the Distribution
Transformer for easy mapping reference.
2. To start your mapping, Use your own House as a starting
point.
3. Check the location of Service Entrance from your House and
track the wiring from there up to the Secondary Line which
you will see above on one side of the road.
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EENG 80 : Electrical Apparatus and Devices
4. From there, follow the Secondary Line to Locate where is the
Distribution Transformer your House is connected. Make
sure to record the Transformer Type and Rating.
5. Draw the connection of the Transformer from the Primary
Line to the Secondary Line.
6. And then start the mapping from the Transformer Location.
7. First, determine the End to End Connection of the Secondary
Line. And from there, start plotting the connection.
8. Survey and check all the Houses connected on the DT, make
sure to plot and mark it on your printed Google Map Sheet.
Refer on the sample Figure 3 only to visualize the connection
reference.
Figure 3. Distribution Transformer Mapping Sample
9. Continue plotting until all connections are already
determined.
10. Assume Power Load in kW per household then,
11. After the survey, start your final Layout on the Autocad
Software. Make sure that all your data and connections are
all visible. And do not forget to include the “Legend” on your
drawing for easy reference.
12. Your Drawing shall include the Vicinity Map, Transformer
Mapping Layout and the Single Line Diagram of your
Transformer connections.
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EENG 80 : Electrical Apparatus and Devices
IV. RESULTS AND DISCUSSION
A. Site Location
B. Transformer Type and Rating
C. Computation
i. Assumed KWload rating per House based on DT Rating
ii. Pload in KW
No. of Houses connected * KWload
iii. KVA load considering 95%pf
Use the formula for the Apparent Power
S = P / p.f. where P = Real Power and p.f. = Power Factor
iv. Transformer Loading %
% = KVAload / KVA Rating
D. Mapping Layout (As Shown on Class Discussion)
E. Transformer Connections (SLD)
V. CONCLUSION
VI. REREFENCE PHOTOS
Prepaped by:
Engr. Abegail R. Rareza
Instructor, 2nd Sem, AY 2023-2024
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