TVSS Lightning and
Equipment Protection
Presented by
Scott Peele PE
TVSS Lightning and Equipment
Protection
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O
O
O
O
What is a Surge or Lightning.
Coupling on the electrical system
Understanding TVSS or SPD protection
Grounding for Lightning
Recommended Practices
What is a Surge?
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O
A surge is a Transient
A Transient can be classified into two
categories, impulsive and oscillatory
Impulsive
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This is the category that TVSS (Transient
Voltage Surge Suppressor) SPD Surge
Protection Device) equipment is designed
to mitigate.
Sources of Transients
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Lightning
Z
Z
O
Static
Arc Welding
Switching
Z
Z
Z
contactor
relays
SCR’s
1989-93 Ave Lightning Flash Density
Key
# of cloud to
ground flashes
per sq kM/year
http://Lightning Detection Network
Lightning directly attaches and couples into power lines
Internal Transient Sources
Location Exposure Categories for Surge
A
B
C
A
Underground
Service Connection
B
C
Overhead
Service
Connection
Applicable Standards for surge protection at locations A, B and C
IEEE C62.41 Cat. A
IEEE C62.62
UL 1449
IEEE C62.41 Cat. B
IEEE C62.62
UL 1449
IEEE C62.41 Cat. C
IEEE C62.62
IEEE C62.1/11
Transient Suppressor Protection
Relative Performance
Percent of
Nominal
Voltage
Typical Energy Limits
of Suppressor
300
Clamping Level Determined
by Energy in Impulse and
Impedance of Source
200
100
Lower Clamping Limit
Nominal
Voltage
106%
87%
1
0
0.001
0.01
0.1 0.5 1.0
610 30 100
2 10
1000
100 Seconds
10000 Cycles
Lightning and Switching Standard ANSI/IEEE Test
Waveforms
Standard: 100-kHz Ring Wave
0.8
0.4
Standard: Combination Wave
1.0
Rise time = 0.5 μsec
10 μsec
Rise time = 1.2 μsec
0.8
0.6
0
0.4
-0.4
0.2
-0.8
20
Time in μsec
40
Simulates transients generated
by switching loads
0
Duration = 50 μsec
High energy
20
60
40
Time in μsec
80
Simulates surges generated by
direct coupled from lightning
From: ANSI/IEEE Standard C62.41 &45
Test Waveforms as Described
by ANSI / IEEE C62.41 - 1991
Category
A3
6kV
200A
100kHz
Category
B3
6kV
500A
100kHz
6kV
1.2/50
Category
C3
20kV
1.2/50µsec
10kA
8/20µsec
3kA
8/20
Clamping Action of SPD or TVSS
Clamped
Surge
Voltage
Incoming
Surge
Voltage
TVSS
Surge
Current
“Protected”
Load
Equipment
SPD Application Guide
Transient
Surge
Suppression
Devices
MOV
Avalanche
Diode
Gas
Tube/Gap
Data Lines
Telecom
(Primary)
Telecom
(Secondary)
AC Power
Lines
DC Power &
Automotive
Typical Transient Surge Suppressor Applications
Harris Semiconductor
Gas Tube Suppressor Element
Gas tube
symbol
Spark-over performance for
successive strikes at 10 kV/us,
100V and .02 us/small division
Metal Oxide Varistors
Metal-oxide varistors
various ratings
same symbol
MOV clamping at three
different surge current levels
- 10, 50 and 250A, with 8x20
waves, 40V/small div, 5
us/small div
Silicon Avalanche Diode Suppressor
Element
Silicon
avalanche
devices
symbol
Avalanche diode clamping
performance at two different
current levels. 20 and 140A, 10
x 1000 us impulses 1V/2ms
small div
Interpretation for IEEE Std 10501996
The caution that "the use of one or more isolated ground rods as the
signal reference ground is a safety hazard and is not recommended"
is not explicitly explained in IEEE Std 1050-1996 since it is well
covered in the IEEE Green Book © (IEEE Std 142-1991) and the
IEEE Emerald Book © (IEEE Std 1100-1996).
The most basic safety hazard is that the isolated ground reference
does not have a direct connection back to the system source which
could prevent protective devices from operating because of the high
impedance that is introduced. Equipment damage from transients
such as lightning is also a real concern.
Grounding Problems
Ohm’s Law
Voltage = Current X Resistance
Voltage Difference
Ground Resistance
Current Source Lightning
Average current 30,000 amps
Review Ohms Law
Voltage = Current X Resistance
(Potential)
(amps)
(ohms)
BONDING
Ground
Rod
Develop VOLTAGE
Develop VOLTAGE
Current Source Lightning
Average current 30,000 amps
Ground
Rod
The problem from two different services
and service ground points
Lightning
Television
Receiver
Electric
Service
Entrance
CATV
Voltage Difference
Difficult installation
scenarios
Troublesome electrical
condition
Multiple external
connections or services
to components of the
same system
Transient voltages and
currents at data port
connections
System Bonding
Current
Typical electronic
equipment symptoms
Intermittent lock ups, surge
damage of exposed I/O circuits
or corrupted signals
Bonding and Grounding
O
O
O
O
Phone System
Cable System
LAN System
Control and Communication
Z
Z
O
Transducers
Sensors
Internal Interface
Communications
O
O
O
O
O
Fiber Optic
Optical Coupling
Last resort to float one end of the
grounding this is usually not as successful.
Radio communication
One power source for all systems.
PEC
Type I
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Life cycle rating category C3
Impulses up to 20,000 per phase
Standard features include: Internal
and external LEDs, Form C
contacts, & Audible Alarm
Choice of Options:
Z
Z
Z
Z
O
Disconnect
Transient counter
Remote monitor panel
NEMA 3R, 4, or 4x enclosures
10 year parts warranty
PEC Type C-100/C-150
PowerSure Panel Medium Exposure
Liebert AC Power Medium Exposure TVSS, on distribution
and sub-distribution panels, or any medium exposure
locations.
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Fault Current Rating (AIC): 65 kAIC
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Surge Current Ratings: 100kA, 160kA
100kA - 6.0”x4.0”x3.0”
160kA - 8.0”x6.0”x4.0”
z50 Ω EMI/RFI Attenuation: 40 dB
100KA
160KA
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Dimensions:
z
Status Indication: LED, Dry Contacts
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Certifications: UL 1449, CUL
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Warranty: 5 Years Parts
PEC Type C-50
PowerSure Panel Low Exposure
Liebert AC Power Low Exposure TVSS, on subdistribution panels, branch panels, or equipment in low
exposure locations.
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Fault Current Rating (AIC): 14 kAIC
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Surge Current Ratings: 25kA, 50kA, 100kA
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Dimensions: 4.72”x4.72”x2.36”
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50 Ω EMI/RFI Attenuation: 40 dB
z
Status Indication:LED, Dry Contacts
z
Certifications: UL 1449, CUL
z
Warranty: 10 Years Parts
UL 1449 Suppressed Voltage Rating
(Standard Voltage Rating)
L-N
L-G
L-L
N-G
120/208
400
400
700
400
277/480
800
800
1500
800
240
700
800
480
1500
1500
Recommended practices
¾ Single Point Grounding of Systems
¾ Visual check grounding system and system
bonding point
¾ Conduct risk evaluation (identify vulnerable
appliances, equipment, and telephone and
computer systems)
¾ Surge protection of external services
¾ Additional internal SPD at equipment
¾ Conductor length short to SPD