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1

What You Need to Know about
Surge Protection
Curtis McCombs
2015

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

•

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

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

This is done by diverting and limiting
damaging transient voltages and currents
...

> A surge can contain
thousands of volts and
thousands of amps
...
6 milliseconds
Transient event (between red lines) approximately 500 microseconds

What is NOT a Transient Surge?
Harmonics

Sustained
Overvoltage

Powerfactor
Imbalance

Undervoltage

Surge Protective Devices are designed to protect against
one thing

Confidential Property of Schneider Electric

Transient Surge

Where do Transient Surges Come From?
Elevators
Pump
Motors

Lightning

Electrical Accidents

Air conditioners

20% outside

80% inside
Air compressors

Switching Cap Banks

Blower Motors
Office Copiers
Oscillatory transients
Typical of Internal events
(Smaller, lower energy)

Utility Grid Switching
Impulse transients
Typical of External events
(Larger, higher energy)

The Effects of Transients on Business

$80B

“Power related problems cost companies over
$80 billion a year”
(Source: Lawrence Berkeley National Laboratory)

“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

Transients – A Problem of “The Electronic Age”
Expanded Use of Electronics
•

•
•
•
•
•
•
•
•

Sensitive Instrumentation
Computerized Work Stations
Industrial Machine Tools
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

How does an SPD work?

SPD Method of Operation
1
...


2
...

4
...


6
...


Confidential Property of Schneider Electric

The SPD is installed in a parallel
path with respect to the load
...

Current will flow through the path
of least resistance
...

NO SPD will shunt 100% of the
initial surge energy away from the
load
...

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
...


Remember - Majority of
disturbances come from
within a Facility
(80%)

L

SPD

SPD
SPD

SPD

Loa
d

N
Service Entrance
ANSI/IEEE C62
...
1 (Cat C)
Confidential Property of Schneider Electric

Distribution
(Cat B)

Branch
(Cat B)

Point of Use
(Cat A)

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’)

Panels feeding critical loads – IEEE Emerald Book
– “For large surge currents, this diversion is best accomplished in several stages
...
”

Critical loads

–

Point of Use

Recommended Protection Levels
•
•
•
•

kA ratings may be modified to correspond with the intensity and frequency of
transients
...
may require an increased kA rating
...

The dollar value of sensitive electronic equipment which receives power from the
Branch Panel needs to be considered
...
For each level of protection (cascading) cut the kA rating by half
...

– can be provided as retrofit for switchboards (I-Line mount), motor
control centers, and bus duct
...


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

How Big of SPD is Needed?
SE Lightning Study

> July 15, 2000 Tampa Bay
Area
> National Lightning
Detection Network

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

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

SE Lightning Study (cont)

IEEE C62
...
1-2002
It depends on where the
stroke hits — but ANSI/IEEE
indicates
30% or less of the stroke
current would enter a
facility
...


24

National
Electrical Code
Section 280
• Surge Arresters – Above 1,000 volts

Section 285
• Surge Protective Devices (SPDs)
1,000 volts and below

25

National
Electrical Code
708 – Critical Operation
Power System

C
...
P
...
“

Surge Protection Devices:
Surge protection devices shall be
provided at all facility distribution
voltage levels
...
8 - Emergency Systems


...


27

Underwriters
Laboratories
Industry Standard

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)

ANSI/UL 96A
Lightning Protection Systems
ANSI/UL 1283
Electromagnetic Interference filters

28

Institute of Electrical
and Electronics
Engineers
Industry Guidelines

ANSI/IEEE C62
...
1 – 2002
IEEE Guide on the Surge Environment in Low
Voltage (1000V and Less) AC Power Circuits:

ANSI/IEEE C62
...
2 – 2002
IEEE Recommended Practice on characterization
of Surge Voltages in 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
...
41
...
41
...
45-2002
IEEE Recommended Practice on Surge Testing for Equipment Connected to
Low Voltage AC Power Circuits:
Guideline

ANSI/IEEE C62

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