High Voltage
Electrical Equipment
Failure Diagnosis
Presented by:
Spencer Tang & Terence Ng
T&T Inspection & Engineering Sdn Bhd
High Voltage Electrical Equipment Failure Diagnosis
Definition of High Voltage (H.V. / H.T.)
– According to IEC standard,
High voltage is defined as those with more than
1000V (>1000V AC) for alternating current
low voltage (50~1000V AC) and extra-low voltage
(<50V AC) circuits, in the context of building wiring
and the safety of electrical apparatus.
– In South East Asia, HV is ranging from
1kV (1000V), 3.3kV, 6.6kV, 11kV, 22kV,
33kV, 132kV, 230kV, 275kV, 400kV & 500kV.
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Map of the Asean
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High Voltage Electrical Equipment Failure Diagnosis
Characteristic of High Voltage
– Higher voltage required higher insulation level
– Ability to penetrate insulation material (air,
vacuum, gas, oil, XLPE, PILC, porcelain, etc)
due to deterioration / aging / interruption /
human error, etc and create short circuit /
discharge between phase to phase / phase to
ground
– resulting severe facility damage / loss, injury /
death
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High Voltage Electrical Equipment Failure Diagnosis
NDT Technology of Ultrasound
– a method to detect HV fault symptom
(electrical partial discharge – E.P.D.) from a
safe distance
– Provide safe access via structure borne and
airborne method without direct expose to the
live part / component.
– Highly sensitive ultrasound instrument
coupled with qualified inspector will able to
detect HV fault symptom (eg: corona,
tracking, arcing, mechanical looseness and
etc)
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E.P.D. at 33kV VCB – Cable VOID
Cable insulation void at cable compartment
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E.P.D. at 33kV VCB – Cable VOID
Cable insulation void at cable compartment
2007
Jul 2008
Oct 2008
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E.P.D. at 33kV VCB – Busbar
Busbar insulation deterioration – corona
partial discharge
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E.P.D. at 33kV VCB – Breaker Contact
Chemical reaction on conductor
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E.P.D. at 132kV Lightning Arrester
Internal partial discharge at porcelain
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E.P.D. at 33kV Overhead Disc Isolator
Airborne detected PD at disc isolator
suspension clamp – sharp edges/
oxidization / deterioration
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High Voltage Electrical Equipment Failure Diagnosis
mechanical vibration / looseness in HV
breaker causes by
– the resonance of electrical frequency (50Hz /
60Hz) or electrical harmonics
– workmanship issue during on site installation
(eg: tightening / torque, panel and floor
leveling, greasing, etc)
– Operator ignorant or mechanism error (eg:
breaker misalignment, breaker arm bent,
shutter jammed, etc
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Mechanical vibration / looseness in HV breaker
Looseness detected at breaker & busbar
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High Voltage Electrical Equipment Failure Diagnosis
Repair urgency on partial discharge
detected:
– Rate of deterioration
– Location of the PD detected
– Loading fluctuation - on/off, surge start, peak
load
– Surrounding environment condition – seaside,
chemical industry, dusty area…
– External factors – animal, human error…
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Repair urgency on PD detected
11kV CT flashover during breaker surge
start after maintenance due to ignorant
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Repair urgency on PD detected
Dusty and salty environment induced
speedy deterioration at 33kV VCB
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Repair urgency on PD detected
High moisture environment induced
oxidization & chemical reaction
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Repair urgency on PD detected
PD chemical effect on metal panel
Before
After
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Repair urgency on PD detected
Close PD location increase rate of
deterioration
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Repair urgency on PD detected
External factor
– Minor corona partial discharge give way in 7 days due
to road construction
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Repair urgency on PD detected
Client common question to inspector:
How long does the PD symptom can last before it
flashover??
Can we arrange shut down after our production
peak time, may be about 6 months later??
Should we shut down by tonight??
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Perfect match of Ultrasound and Thermography
Ultrasound (US) – hear what we cannot
hear; Thermography (IR) – see what we
cannot see.
– Technology limitation but not weakness.
Integration of US & IR will supplement the
survey findings and produce a better
diagnosis result
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Perfect match of Ultrasound and Thermography
11kV RMU required immediate attention
y
y
39.0 °C
39.0 °C
35
Sp1:temp 32.0
30
35
Ar1:max 34.5
26.0
30
26.0
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Perfect match of Ultrasound and Thermography
Localizing the fault area
F LI R S ys tem s
FLIR Systems
70.0 °C
60
50
Sp1:temp 44.6
40.0 °C
38
36
34
40
Ar1:max 67.6
30
25.0
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30
29.0
24
Perfect match of Ultrasound and Thermography
Localizing the fault area
31.9 °C
y
39.0 °C
35
30
Ar1:max 36.1
30
28
25
27.0
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High Voltage Electrical Equipment Failure Diagnosis
NDT technology ease the inspector / owner to
visualize & localize the faults
How is the HV partial discharge look like in our
visual view???
– Tx HV corona ring;
43.0 °C
Ar2:max 40.2
40
30
Ar3:max 30.5
Ar1 :max 40.1
20
19.0
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Tx HV Cable - corona ring partial discharge
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Tx HV bushing partial discharge
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Tx HV bushing partial discharge
50.0 °C
Ar3:max 44.3
45
Ar2:max 49.1
40
Ar1:max 46.1
38.0
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Electrical partial discharge effect to plant/climber
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HV flashover
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High Voltage Electrical Equipment Failure Diagnosis
To conduct a safe and effective inspection
on high voltage electrical equipment, we
should well understand and aware on:
– The safety measure of the HV equipment to
be inspected;
– Our NDT instruments’ strength and limitation;
– Be observant and sensitive to the on-site
condition of the HV equipment;
– “a careful inspector will live longer than a hero
(fool) in HV electrical system”
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230kV GIS
FLIR Systems
46.0 °C
45
40
35
:max 30.7
:max 32.8
30
:max 30.8
25.0
FLIR Systems
46.0 °C
45
40
35
30
25.0
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230KV GIS
FLIR Systems
46.0 °C
45
40
35
:max 32.8
:max 30.9
30
25.5
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3MVA Pauwels Trafo
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High Voltage Electrical Equipment Failure Diagnosis
Glad to share with you,
Thank you
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