This document provides an overview of surge protection and transient surges. It defines a transient surge as a brief high-voltage spike lasting millionths of a second. The document discusses how surges can damage equipment and cost businesses billions annually. It describes how surge protective devices (SPDs) work by diverting damaging currents away from equipment. The document emphasizes that proper SPD location and installation is important for effective protection. It provides guidance on selecting appropriate protection levels based on surge risk and discusses relevant industry codes and standards.

1. What You Need to Know about
Surge Protection
1
Surge Protection
Curtis McCombs
2015

2. Course Objectives
Upon completion of this course you will be able to:
• Define the basic principles of a transient surge
• Identify the causes of surge events
• Describe how transient surge affects you today• Describe how transient surge affects you today
• Explain how an SPD works
• Describe how to use surge protection correctly
• Identify important surge protection codes and
standards and their requirements

3. Surge Protection Overview
3

4. What is the purpose of a Surge Arresters
and Surge Protective Devices (SPDs) ?
> To protect your distribution equipment
> To protect your critical and sensitive equipment
Confidential Property of Schneider Electric
This is done by diverting and limiting
damaging transient voltages and currents.

5. What is a Transient Surge?
> A surge or transient is a
voltage spike that only
lasts a few millionths of a
second (the “blink of an
eye” is thousands of
times longer than the
Confidential Property of Schneider Electric
1 cycle at 60 Hz = 16.6 milliseconds
Transient event (between red lines) approximately 500 microseconds
times longer than the
typical surge).
> A surge can contain
thousands of volts and
thousands of amps.

6. What is NOT a Transient Surge?
Sustained
Overvoltage
Harmonics
Confidential Property of Schneider Electric
Undervoltage
Powerfactor
Imbalance
Surge Protective Devices are designed to protect against
one thing Transient Surge

7. Where do Transient Surges Come From?
20% outside
Elevators
Air conditioners
Lightning
Electrical Accidents
Pump
Motors
80% inside 20% outside
Blower Motors
Switching Cap Banks
Utility Grid Switching
Air compressors
80% inside
Office Copiers
Impulse transients
Typical of External events
(Larger, higher energy)
Oscillatory transients
Typical of Internal events
(Smaller, lower energy)

8. $80B$80B “Power related problems cost companies over
$80 billion a year”
(Source: Lawrence Berkeley National Laboratory)
The Effects of Transients on Business
“Industry experts estimate that power
surges cost businesses $26 billion annually
in lost time and equipment repairs and
replacements”
(Source: Insurance Institute for Business & Home Safety)
High Facility Maintenance Costs
Equipment Failure
• Long-term System Degradation
• Process disruptions
• Data Loss or Corruption
• Costly Downtime
• Safety to drinking water

9. Expanded Use of Electronics
• Sensitive Instrumentation
• Computerized Work Stations
• Industrial Machine Tools
• Automated Irrigation Controls
Transients – A Problem of “The Electronic Age”
• Automated Irrigation Controls
• Programmable Logic Controllers
• Security Systems
• Motor Control Systems
• Communications
• Data Centers
What doesn’t have some level of
‘control’ associated with it today ??

10. How a Surge Protective Device Works
10

11. How does an SPD work? SPD Method of Operation
1. The SPD is installed in a parallel
path with respect to the load.
2. When a surge voltage does come
down the line, the SPD will
respond in nanoseconds creating a
low impedance path through the
components within the SPD.
3. Current will flow through the path
of least resistance.
4. The SPD becomes the path of
least resistance and shunts the
damaging energy before it is
The purpose behind installing any SPD is to divert
damaging voltage and currents away from down stream
equipment.
Confidential Property of Schneider Electric
damaging energy before it is
forced through the down stream
protected equipment.
5. NO SPD will shunt 100% of the
initial surge energy away from the
load.
6. There is always some
voltage/current that will be pushed
through the load.
7. But if the SPDs are installed
correctly and in the proper location,
this Surge Remnant is well below
the damaging level of the protected
equipment.

12. The Best Surge Protective Device
is Only as Good as its
Practical Application of Surge Protection
is Only as Good as its
Location and Installation

13. Cascading - Location
Cascading (layering) your protection
throughout your facility insures proper
protection for your equipment.
L
Remember - Majority of
disturbances come from
within a Facility
(80%)
Confidential Property of Schneider Electric
Loa
d
N
SPD
SPD
SPD
SPD
Point of Use
(Cat A)
Branch
(Cat B)
Distribution
(Cat B)ANSI/IEEE C62.41.1
Service Entrance
(Cat C)

14. Where to install Surge Protection
At the service entrance – to protect from externally generated surges
– Externally generated surges can be the highest energy surges
At any panels that have conductors that exit the building – to protect from
alternate paths for lightning induced surges to enter
– Outdoor lighting
– Rooftop HVAC
– Outdoor equipment (Points often identified as ‘back door’)– Outdoor equipment (Points often identified as ‘back door’)
Panels feeding critical loads – IEEE Emerald Book
– “For large surge currents, this diversion is best accomplished in several stages.
The first diversion should be performed at the entrance to the building, then,
any residual voltage resulting from the action of the first protective device can
be dealt with by a second protective device at the power panel of the
computer room, or at the terminals of a connected load, or both.”
Critical loads
– Point of Use

15. Recommended Protection Levels
• kA ratings may be modified to correspond with the intensity and frequency of
transients.
• High lightning areas or areas with a high frequency of Utility grid switching surges,
etc. may require an increased kA rating.
• The higher the frequency of surges, the higher the kA rating should be.
• The dollar value of sensitive electronic equipment which receives power from the
Branch Panel needs to be considered.
Service Entrance
Up to 240 kA Distribution
Rule of Thumb:
The higher the kA rating on the product, the better its withstand capability and overall
robustness. For each level of protection (cascading) cut the kA rating by half.
Load
SPDSPD SPD
SPD
Branch
80-120 kA
Up to 240 kA Distribution
120-160kA

16. Lead Length - Installation
Resistance Inductance
Current
Impact on Clamping Voltage

17. Lead Length Challenges
Limited
Horizontal distance
Limited
space
between
panels

18. Integral versus External
Integral
– can be provided in all new equipment such as switchgear,
switchboards, panelboards, motor control centers, and bus duct.
– can be provided as retrofit for switchboards (I-Line mount), motor
control centers, and bus duct.
ExternalExternal
– is required for retrofit for panelboards or in cases where space inside
the equipment is not available.
Benefits of Integral versus External
– Minimized lead lengths – improves overall performance and protection
– Reduces footprint required by external products
– Coordinated design between SPD and distribution equipment

19. How Big of SPD is Needed?
SE Lightning Study
> July 15, 2000 Tampa Bay
Area
> National Lightning
Detection Network

20. SE Lightning Study (cont)
> 14 Hour Storm
> 33,863 Recorded
Lightning Strikes
> Cloud to Ground Strikes

21. SE Lightning Study (cont)
> 2,597 Positive Strokes
98% less than 60kA
> 31,266 Negative Strokes
98% less than 60kA
2 strokes approached 180 kA

22. SE Lightning Study (cont)
It depends on where the
IEEE C62.41.1-2002
It depends on where the
stroke hits — but ANSI/IEEE
indicates
30% or less of the stroke
current would enter a
facility.

23. Industry Codes, Standards and other
reference documents.
23
reference documents.

24. National
Electrical Code
Section 280
• Surge Arresters – Above 1,000 volts
Section 285
24
Section 285
• Surge Protective Devices (SPDs)
1,000 volts and below

25. National
Electrical Code
C.O.P.S
"power systems for facilities or parts of
facilities that require continuous
operation for the reasons of public
safety, emergency management,
national security, or business
continuity.“
25
708 – Critical Operation
Power System
continuity.“
Surge Protection Devices:
Surge protection devices shall be
provided at all facility distribution
voltage levels.

26. National
Electrical Code
Emergency Systems
Safe egress
Panic control
Building safety systems (alarm,
communications)
Building mechanical systems (elevators,
ventilation)
Prevention of catastrophic industrial
process failure
26
700.8 - Emergency Systems
process failure
Surge Protective Devices:
A listed SPD shall be installed in or on all
emergency systems switchboards and
panelboards.
2014.

27. Underwriters
Laboratories
ANSI/UL 1449
Surge Protective Devices
Third Edition effective September 2009
TVSS to SPD
Introduction to Types of SPDs (Type 1,2,3,4)
Voltage Protection Rating
Nominal Discharge Current Rating
Fourth Edition effective September 2014
Clarification
Additional testing not in effect till 2016 (PV)
27
Industry Standard
Additional testing not in effect till 2016 (PV)
ANSI/UL 96A
Lightning Protection Systems
ANSI/UL 1283
Electromagnetic Interference filters

28. Institute of Electrical
and Electronics
Engineers
ANSI/IEEE C62.41.1 – 2002
IEEE Guide on the Surge Environment in Low
Voltage (1000V and Less) AC Power Circuits:
ANSI/IEEE C62.41.2 – 2002
IEEE Recommended Practice on characterization
of Surge Voltages in Low Voltage AC Power
Circuits:
ANSI/IEEE C62.45 – 2002
IEEE Recommended Practice on Surge Testing for
Equipment Connected to Low Voltage AC Power
28
Industry Guidelines
Equipment Connected to Low Voltage AC Power
Circuits:
ANSI/IEEE C62.62
Test Specifications for Surge-Protective Devices
(SPDs) for Use on the Load Side of the Service
Equipment in Low-Voltage (1000 V and Less) AC
Power Circuits
ANSI/IEEE C62.72
IEEE Recommended Practice on the
Application of Surge Protective Devices in
Low Voltage AC Power Circuits:

29. ANSI/IEEE C62.41.1-2002
IEEE Guide on the Surge Environment in Low Voltage (1000V and Less) AC
Power Circuits:
ANSI/IEEE C62.41.2-2002
IEEE Recommended Practice on Characterization of Surge Voltages in Low
Voltage AC Power Circuits:
Codes & Standards
Voltage AC Power Circuits:
GuidelineGuideline
ANSI/IEEE C62.45-2002
IEEE Recommended Practice on Surge Testing for Equipment Connected to
Low Voltage AC Power Circuits:
ANSI/IEEE C62.72-2007
IEEE Recommended Practice on the Application of Surge Protective Devices in
LowVoltage AC Power Circuits:

30. Questions ?
30
THANK YOU !!