Lesson 11: Transformer Name Plate Data and Connections
[Pages:13]Lesson 11_et332b.pptx
3/2/2018
ET 332b Ac Motors, Generators and Power Systems
LESSON 11: TRANSFORMER NAME PLATE DATA AND CONNECTIONS
1
Lesson 11_et332b.pptx
LEARNING OBJECTIVES
After this presentation you will be able to: Identify transformer polarity using dot and conventional labeling. Explain and interpret information found on transformer name
plates. Compare and contrast the performance of three phase transformer
connections. Indentify the schematic symbols of potential and current
transformer. List characteristics on these devices and explain how they relate to performance.
2
1
3/2/2018
Lesson 11_et332b.pptx
TRANSFORMER MARKINGS AND POLARITY
Dot Notation - Terminals marked with a dot are considered instantaneously positive
A I1 +
EAB
B
-
+
I2
C
0 degree
shift
-
D
N1
N2
Above Terminals A and C are positive at the same time
Phasor Diagram
EAB
ECD
0 degrees
3
Lesson 11_et332b.pptx
TRANSFORMER MARKINGS AND POLARITY
A + +
EAB
B
- I2
C
180 degree
+
shift
+ D
Above Terminals A and D are positive at the same time
Phasor Diagram
EAB
ECD
180 degrees
4
2
3/2/2018
Lesson 11_et332b.pptx
TRANSFORMER MARKINGS AND POLARITY
Conventional Labeling H = high voltage side X = low voltage side
H1
+
+
X1
H2
-
0 phase shift X2
-
Terminal H1 more positive than H2. On secondary side X1 more positive than X2
5
Lesson 11_et332b.pptx
TRANSFORMER MARKINGS AND POLARITY
Conventional Labeling H = high voltage side X = low voltage side
H1
+
H2
-
-
X2
180 phase shift
X1
+
+
Note: Polarity of secondary is reversed creating 180 degree phase shift across transformer
6
3
3/2/2018
Lesson 11_et332b.pptx
TRANSFORMER NAMEPLATE DATA
Voltage ratings
high side and low side values (no-load values)
Additional Voltage Markings
Dash (-) = Indicates voltages from different windings
Slant (/) = voltages from same winding Cross(x) = voltages obtained by series
or parallel connection of two part windings Wye (Y) = wye-connected windings
7
Lesson 11_et332b.pptx
TRANSFORMER VOLTAGE RATINGS
Single Phase Examples
240/120 240x120 240-120
Three Phase Example
240 V winding with a center tap
Two part winding that can be connected in series for 240 V and parallel for 120 V
A 240 V and separate 120 V winding
12470-480Y-277 V
Two winding transformer. Wye connected secondary with 277V and 480 V available
8
4
3/2/2018
Lesson 11_et332b.pptx
OTHER NAME PLATE DATA
Frequency kVA
Rated frequency of transformer
Rated Apparent power of transformer
Apparent power rating determined by construction and cooling- oil cooled. Oil also provides insulation
Power ratings AO rating - natural convection air and
oil. FA rating - natural convection of oil and
forced air FOA rating - forced air and oil circulation
9
Lesson 11_et332b.pptx
TRANSFORMER POWER RATINGS
Typical ratings 30/40/50 MVA AO/FA/FOA
Dry Type Insulated transformers (no oil) Typical at voltages of 15 kV and below
Classes AA - dry type, self-cooled, natural convection of air AFA - Dry type, forced-air cooling AA/FA Dry type self-cooled/forced air cooled
Dual rating that requires fans
Forced oil by circulating
pumps
Forced air by radiators and
fans
10
5
3/2/2018
Lesson 11_et332b.pptx
OTHER NAME PLATE DATA
Percent Impedance
Impedance measured at indicated temperature. Base S and V values are the ratings of the transformer
Temperature Rise
Maximum allowable temperature rise
Heat effects the insulation Excessive heating reduces life of transformer
Class
Insulating medium and cooling ( see previous slide)
11
Lesson 11_et332b.pptx
BASIC IMPULSE LEVEL
(Basic Impulse Level) Measures the
BIL
maximum voltage stresses that the
transformer can handle
Impulse tests used to simulate the effects of lightning over-voltages
Voltage surges in excess of the BIL can cause insulation failures
12
6
3/2/2018
Lesson 11_et332b.pptx
THREE PHASE TRANSFORMER CONNECTIONS
Transformers increase voltage, decreasing current in power systems. Lower I means less power loss due to I2R losses in lines, cables, transformers, etc
Generator
Step up transformer
I V
V I
Step down transformer
Three phase transformers 3 single-phase units can form 3-phase bank
or Single three-phase transformer (3 separate cores in a single tank)
Step up/down transformers are different connections of 1-f units or coils based on wye-delta configurations
13
Lesson 11_et332b.pptx
THREE PHASE TRANSFORMER CONNECTIONS
Examples from the field
Three-Phase Transformer Single Unit, Substation Type
Three Phase Bank Three individual Transformers
14
7
3/2/2018
Lesson 11_et332b.pptx
DELTA-DELTA (D-D) CONNECTION
primary
secondary
Parallel coils are part of same transformer or core
Phase diagram
Advantages: Absorbs unbalance of load. Unbalance I circulates in delta. Lose one transformer and can still operate
Disadvantages: No natural neutral
15
Lesson 11_et332b.pptx
WYE-WYE CONNECTION
C Three phase, four-wire , grounded wye primary A
B
Advantages:
C
A
N
Two voltage levels available
B
H1
H2
H1
H2
H1
H2
Graded High voltage insulation Easy balancing between 1-f
and 3-f loads
c
X3
X2
X1
X3
X2
X1
X3
X2
X1
Disadvantages:
a
b c
n 120/208
208
208 208
120 120 120
a b
Single phase short circuit currents passed. Zero sequence (3rd Harmonics passed)
Three 7200 - 240/120 V transformers
Primary VAn = VBn = VCn = 7200 V H1 - H2 VLL = 12470 V Secondary Van = Van = Vcn = 120 V X1 - X2 VLL = 208 V
Total Bank power: S1 + S2 +S3 = ST
16
8
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related download
- nato conventional military symbols
- finite state machines edu
- identifying main idea and supporting details
- chapter 2 simple random sampling iit kanpur
- lab 12 plasmid mapping student guide
- lesson 11 transformer name plate data and connections
- standard p id symbols legend industry edrawsoft
- terminal markings and internal wiring
- november 19 2015
- coconino community college education that works for you
Related searches
- data and analytics
- data and quality improvement
- data and time meeting planner
- ospi data and reports
- united nations data and statistics
- examples of qualitative data and quantitative
- name of elements and their symbols
- lesson 11 analyzing word choice
- data and graph lesson plans
- stock market today news data and summary
- cdc data and statistics
- practice and homework lesson 11 2