Transformer Tests
Transformer Tests
Transformer Tests
At
At Factory
Factory and
and In
In Field
Field
H. Jin Sim
Waukesha Electric Systems
9
9 ASSESSMENT
ASSESSMENT OF
OF QUALITY
QUALITY AND
AND RELIABILITY
RELIABILITY
9
9 VERIFICATION
VERIFICATION OF
OF DESIGN
DESIGN
9
9 COMPLIANCE
COMPLIANCE WITH
WITH INDUSTRY
INDUSTRY STANDARDS
STANDARDS
Test
Test Classification
Classification
¾
¾ Routine
Routine
¾
¾ Design
Design
¾
¾ Other
Other
DIE
DIE ELECTRIC
ELECTRIC TESTS
TESTS PERFORMANCE
PERFORMANCE THERMAL
THERMAL TESTS
TESTS OTHER
OTHER TESTS
TESTS
CHARACTERISTICS
CHARACTERISTICS
TRANSIENTS 1)
1) No-Load
No-Load Loss
Loss 1)
1) Winding
Winding Resistance
Resistance *1)
*1) Insulation
Insulation Capacitance
Capacitance
1)
1) Lightning
Lightning Impulse
Impulse 2)
2) %% Exc.
Exc. Current
Current 2)
2) Heat
Heat Run
Run Test
Test and
and dissipation
dissipation factor
factor
ii Full
Full Wave
Wave 3)
3) Load
Load Loss
Loss iOil
iOil Rise
Rise 2)
2) Sound
Sound Level
Level Tests
Tests
ii Chopped
Chopped Wave
Wave 4)
4) %% Impedance
Impedance iWdg.
iWdg. Rise
Rise 3)
3) 10
10 kV
kV Exc.
Exc. Current
Current
ii Steep
Steep Wave
Wave 5)
5) Zero
Zero Sequence
Sequence iHot
iHot spot
spot rise
rise 4)
4) Megger
Megger
Impedances
Impedances 3)
3) Over
Over Load
Load Heat
Heat Run
Run 5)
5) Core
Core Ground
Ground
6)Ratio
6)Ratio Tests
Tests 4)
4) Gas
Gas In
In Oil
Oil *6)
*6) Electrical
Electrical Center
Center
2)
2) Switching
Switching Impulse
Impulse 7)
7) Winding
Winding Resistance
Resistance 5)5) Thermal
Thermal Scan
Scan *7)
*7) Recurrent
Recurrent Surge
Surge
8)
8) Dew
Dew Point
Point
LOW (POWER)
9)
9) Short-Circuit
Short-Circuit Test
Test
FREQUENCY
*10)
*10) Control
Control Circuit
Circuit Test
Test
*11)
*11) Test
Test on
on Series
Series Transformer
Transformer
1)
1) Applied
Applied Voltage
Voltage *12)
*12) LTC
LTC Tests
Tests
2)
2) 1∅
1∅ Induced
Induced *13)
*13) Preliminary
Preliminary Ratio
Ratio Tests
Tests
3)
3) Induced
Induced Voltage
Voltage *14)
*14) Test
Test on
on Bushing
Bushing CTCT
4)
4) Partial
Partial Discharge
Discharge *15)
*15) Oil
Oil Preservation
Preservation System
System
*Quality
*Quality Control
Control Tests
Tests
Factory Test
DIELECTRIC ENVIRONMENT
¾Power Frequency (Normal, Abnormal)
¾Natural (Lightning)
¾Man-made (Switching Impulse)
9Major Insulation
9Minor Insulation
9Phase to Phase Insulation
•TEST CIRCUIT:
9Test one terminal at a time, all other terminals are grounded
9Current is measured at other end of winding through a shunt
• TEST CIRCUIT
•Test for each HV Line terminal
•Ground Neutral terminal for all Wye connection, Ground other end of all Delta windings
•All Line terminals to be kept open except test terminal
Witnessing
¾Majority of users do NOT witness factory tests
¾Many users will witness at least Dielectric tests for:
9New supplier
9New, special application design
¾Many users use independent consultants for this
Typical Values of
V ≅ 0.1 – 12.0 kV
Good insulation
PF ≅ DF ≤ 0.5%
Temperature
Sensitive
Testing “Major”
Insulation
PI Comment
Compare the results for each phase to the other phases and to the
earlier readings. More than 2% variance from expected should be
investigated.
Visual Checks
Electrical Testing
Relay Testing / Setting
Operational Testing
Relay Replacement
Thermo-graphic Survey / Inspection
Battery Testing and Maintenance
0
Measures the “transfer function”
-10
of RLC network
-20
-50
-90
Comparisons can also be made
-100
10
4
10
5
10
6 between “Similar” units or
Fre que nc y - Hz
different phases of the same unit
RIV PD
energy solutions WAUKESHA
ELECTRIC
… to power your future SYSTEMS
Field Diagnostic Testing
• Electrical Testing – Partial Discharge Detection
•Impedance measurements
•Core Megger
•Series of Bushing tests (Capacitance, Dielectric Loss,
PF/DF, PD, Visual Inspection)
Critical Transformers:
9 Always follow the Manufacturer’s recommendations
9 It is a good idea to have qualified engineers/technicians from the
manufacturer to perform the installation, testing, and commissioning
work or as a minimum, have them on-site for
consultation/supervision
Thank You