Fluke Offline Workshop

Understanding Electrical and Mechanical Issues from Thermography perspective

Pembicara: Hifdhul Mulki F, Application Engineer

Thermography Technology
See Beyond Temperature Readings
What is Thermal Image?
An image representing the surface temperature of the object:

BRIGHTER = HOTTER DARKER = COOLER

• Infrared cannot be seen (but can be sensed

by our skin)

• Everything emits infrared radiation

• A camera converts the “infrared image” to a

visible picture

• Infrared allows you to “see” things that you

normally can’t
 What is Thermal Image?

Electrical switchgear Motor External electric pylon

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How is heat transferred?

Conduction
Solid/direct contact
on
ucti
nd
co
Convection convection

Movement of fluid/gas

Radiation radiation

Electromagnetic waves
(Infrared)
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 How does Thermography work?
IR is a form of energy and is a part of electromagnetic spectrum. It is not visible to our eyes.

Infrared detector – Uncooled microbolometer inside

thermal imager can capture infrared wave

Typical array detector size 640x480 pixels

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Introduction to Thermography and
Predictive Maintenance

3 1
Condition- Based Detect/Identify
Maintenance Wastage & Risks

2
Efficient
Troubleshoot Predictive
Approach Maintenance

Key Benefits:
• Reduce random machine breakdown & unplanned downtime
• Optimize operation cost and improve reliability
• Promote overall facility safety especially fire safety
Why Thermography PdM?
• Non-contact
• Little or no interruption to
operations
• Fast
• Extremely effective
• Reduce costly downtime
and equipment damage
Fluke PdM Technologies

Vibration
Condition Testing
Mechanical
Focus PdM
Motor & Drive
Diagnostics

Overall PdM with

Thermal Imaging Power Quality
Condition

Electrical Focus Earth Ground

PdM Condition

Insulation
Condition
Applications (Electrical)

Energized circuits Loose termination Unbalance issue

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Temperature rise on electrical equipment

Source: NETA Maintenance Testing Specifications-2007

Electrical PDM
The No.1 application for thermography.
• Challenges in electrical system maintenance:
1. Most problems in electrical system are not visible until it’s too late.
2. There are many electrical equipment and components spreading across the entire
facility or geographical area.
3. Due to safety, It is not easy to check all electrical components by means of contact.

• Thermal imaging is a key tool for Electrical Predictive Maintenance to see the
unseen problems quickly and safely in the whole electrical system.
What is the possible problem?

Capture from different angles

to confirm thermal pattern
What is the possible problem?
L2 L3 N
L1

Temperature rise in neutral conductor.

Harmonic current skin effect accelerate overheating
Insulation
Area of Current Flow

Conductor
 Applications (Battery Bank)
Battery Cell Overheat Loose Termination Loose Termination

Battery Cell Overheat High strap resistance

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Utilities Application

Bushing and tap Transformer

Transformer High voltage disconnect

 Applications (Mechanical)
Bearing overheat Belt overheat Winding Hotspot

Bearing overheat Coupling overheat Motor & Pump overheat

Motor housing and winding insulation
• Observe motor housing thermal image. Familiarize with normal pattern

Normal thermal pattern Localized hot spot pattern Whole motor housing overheated
pattern

Almost uniform pattern Examine the hot spot.

What is the cause? How hot is it?

Image source: Infrared Institute

Winding insulation temperature classifications
Insulation Temp. Winding Est. Housing Hot
Class Rise Hot Spot Limit Spot Limit*

A 60 oC 110 oC 90 oC

B 80 oC 130 oC 110 oC

F 105 oC 155 oC 135 oC

H 125 oC 180 oC 160 oC

Source: NEMA Insulation Classification
“Half-life” Rule:
Every 10°C over maximum rated temperature, motor’s expected
life is reduced by 50% due to insulation failure!
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Applications (Steam Traps)

Working Trap

Failed Trap

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Applications (Building Moisture & Leaks)

Moisture on walls Moisture on walls

Pipe leaks Pipe leaks

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Jenis transfer panas apa yang digunakan
oleh sensor infrared ketika mendeteksi
suhu?

a. Konduksi
b. Konveksi
c. Radiasi

POLL TIME
Emissivity & Transmissivity
Reflectivity

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Emissivity & Reflectivity
Two False Thermal Patterns

Emissivity Reflectivity
ü Efficiency of infrared energy emission from a ü Emissivity + Reflectivity = 1
material ü The ability of object to reflect infrared light
ü Ranging from 0 to 1 ü Move position or angle to avoid reflection
ü All objects in real world has emissivity less than 1
(only blackbody emissivity is 1)
ü E>0.8  Real temperature pattern
ü E<0.6  Unreliable temperature pattern

Random bright
spot on
Shiny fuse cap has shiny bus bar
lower emissivity
Emissivity
• All objects continually emit infrared energy.
• Some emit more, some emit less depending on its surface material.
•Emissivity describes how efficient/ how well a material surface can emit infrared
energy.
• Emissivity range from 0 to 1. In physics theory, only a black body has a emissivity of 1.
• In real world, any object has emissivity less than 1 and emits less infrared energy than a black body does. E
<1
Emissivity of common material
• Skin 0.98
• Water 0.98
• Paint 0.9-0.95

These values are to be used as a guide only, as emissivity changes depending on the
actual material surface and conditions.
 Shiny fuse cap has
lower emissivity Lower emissivity at bus bar
connection.
How to inspect?
Fuse Inspection
• One of the fuse hotter than the rest
• Detected possible connection issue on fuse
How professional thermographer handle emissivity
•Emissivity is a physical property of all objects and materials.
•Professionals understand this property and work within the limits of the technology.
•Case 1: Qualitative & comparative method:
–Use the same emissivity value on thermal image 0.95.
–Use thermal pattern to identify potential problem
–Use delta T between same material or same component to identify
–Most popular method since the start of this technology.

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Transmissivity

Air

•Transmission is the ability of a material to allow IR radiation to pass

through it (transmit)

•Transmissivity in most cases is 0

•No change needed in most cases, unless…

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Fluke CV400 IR Windows
•Highest arc blast safety rating—63kA
•IP67 for years of maintenance free
• Rugged construction
•AutoGround™ technology instantly grounds
window to enclosure upon installation
•Quick installation
 Overlooking Mistakes in
visual inspection thermal scanning

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Overlooking visual inspection

•For a proper infrared inspection, the

equipment must be fully exposed

•As a thermographer, we see the

equipment in a state most never get
to see

•During your inspection may be the

only time the assets are opened

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Mistakes in thermal scanning

•Thermal imagers are unable to scan

through panel doors or panel shields

•Equipment must be fully exposed

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Mistakes in thermal scanning

•Verify that the target system is

operating at a minimum 40% of load

•Lighter loads don’t produce much

heat, making it hard to detect
problems

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Mistakes in thermal scanning
•Not all problems are hot

•Example: Blown fuses and restricted

flow in cooling systems are indicated
by a cooler than normal signature

•Thermographers must understand

how a machine works and what its
heat-related failure signatures are

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Mistakes in thermal scanning include lens

•Not getting closer to your subjects

•More details can be extracted when you are

nearer to the subject

•How far can my thermal imager scan?

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FOV & IFOV
•Field of View (FOV) is the largest area
that your imager can see at a set distance
ØFOV described in horizontal degrees by
vertical degrees for example
Ø34 °H x 24 °V on typical thermal imager

•IFOV (instantaneous FOV or Spatial FOV

resolution) is the smallest detail that can
be seen at a set distance
ØIFOV is specified in mRad
ØSmaller is better

D:S = Distance to Spot Ratio

IFOV
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Fluke FOV calculator
• http://download.fluke.com/OnlineTools/EN/USEN/FOV_calc_index.html
Easier way to determine optimum distance for your object size
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Mistakes in thermal scanning

•Focus is the single most important thing

to ensure when conducting an infrared
inspection

•Improper focus can lead to incorrect

temperature measurements

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 TERIMAKASIH. “STAY SAFE”

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