TVSS Lightning and Equipment Protection

Presented by

Scott Peele

PE

TVSS Lightning and Equipment Protection

What is a Surge or Lightning.Coupling on the electrical systemUnderstanding TVSS or SPD protectionGrounding for LightningRecommended Practices

What is a Surge?

A surge is a TransientA Transient can be classified into two categories, impulsive and oscillatory

Impulsive

This is the category that TVSS (Transient Voltage Surge Suppressor) SPD Surge Protection Device) equipment is designed to mitigate.

Sources of Transients

LightningStaticArc Welding

SwitchingcontactorrelaysSCR’s

Key# of cloud to ground flashes per sq kM/year

1989-93 Ave Lightning Flash Density

http://Lightning Detection Network

Lightning directly attaches and couples into power lines

Internal Transient Sources

A B C

UndergroundService Connection

OverheadServiceConnection

A B C

IEEE C62.41 Cat. CIEEE C62.62IEEE C62.1/11

IEEE C62.41 Cat. BIEEE C62.62UL 1449

IEEE C62.41 Cat. AIEEE C62.62UL 1449

Applicable Standards for surge protection at locations A, B and C

Location Exposure Categories for Surge

0.001

0.01

0.1

0.5

1.0

61030

100

1000

10000

Cycles

Transient Suppressor Protection Relative Performance

106%87%

NominalVoltage

1

2

10

100

Seconds

300

200

100

0

Typical Energy Limitsof Suppressor

Clamping Level Determinedby Energy in Impulse andImpedance of Source

Lower Clamping Limit

Percent of NominalVoltage

Standard: 100-kHz Ring Wave Standard: Combination Wave

Simulates transients generated by switching loads

0

0.2

0.4

0.6

40 80

0.8 Rise time = 1.2 μsec

Duration = 50 μsec

Time in μsec20 60

1.0

-0.8

-0.4

0

0.4

20 40

0.8 Rise time = 0.5 μsec10 μsec

Time in μsec

Simulates surges generated bydirect coupled from lightning

From: ANSI/IEEE Standard C62.41 &45

High energy

Lightning and Switching Standard ANSI/IEEE Test Waveforms

CategoryA3

CategoryB3

CategoryC3

6kV200A

100kHz

6kV500A

100kHz6kV

1.2/503kA8/20

20kV1.2/50µsec

10kA8/20µsec

Test Waveforms as Described by ANSI / IEEE C62.41 -

1991

Test Waveforms as Described Test Waveforms as Described by ANSI / IEEE C62.41 by ANSI / IEEE C62.41 --

19911991

SurgeCurrent

TVSS

ClampedSurge

Voltage

“Protected”Load

Equipment

IncomingSurge

Voltage

Clamping Action of SPD or TVSS

SPD Application Guide

TransientSurge

SuppressionDevices

Data Lines Telecom(Primary)

Telecom(Secondary)

AC PowerLines

DC Power &Automotive

MOVAvalanche

DiodeGas

Tube/Gap

Typical Transient Surge Suppressor Applications Harris Semiconductor

Gas tube symbol

Spark-over performance for successive strikes at 10 kV/us, 100V and .02 us/small division

Gas Tube Suppressor Element

Metal-oxide varistorsvarious ratingssame symbol

MOV clamping at threedifferent surge current levels -

10, 50 and 250A, with 8x20

waves, 40V/small div, 5 us/small div

Metal Oxide Varistors

Silicon avalanchedevices symbol

Avalanche diode clamping performance at two different current levels. 20 and 140A, 10 x 1000 us impulses 1V/2ms small div

Silicon Avalanche Diode Suppressor Element

Interpretation for IEEE Std 1050- 1996

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

Current Source Lightning Average current 30,000 amps

Voltage Difference

Ground Resistance

Ohm’s Law Voltage = Current X Resistance

Review Ohms Law

Voltage = Current X Resistance(ohms)(Potential) (amps)

Develop VOLTAGEDevelop VOLTAGE

BONDING

GroundRod

GroundRod

Current Source Lightning Average current 30,000 amps

CATV

Electric ServiceEntrance

Television Receiver

Lightning

Voltage Difference Current

Difficult installationscenarios

Troublesome electricalcondition

Typical electronic equipment symptoms

Multiple external connections or services to components of the same system

Transient voltages and Transient voltages and currentscurrents

at data port connections

Intermittent lock ups, surge damage of exposed I/O circuits or corrupted signals

The problem from two different services and service ground points

System Bonding

Bonding and Grounding

Phone SystemCable SystemLAN SystemControl and Communication

TransducersSensors

Internal Interface

Communications

Fiber OpticOptical CouplingLast resort to float one end of the grounding this is usually not as successful.Radio communicationOne power source for all systems.

Life cycle rating category C3 Impulses up to 20,000 per phaseStandard features include: Internal and external LEDs, Form C contacts, & Audible AlarmChoice of Options:

DisconnectTransient counterRemote monitor panelNEMA 3R, 4, or 4x enclosures

10 year parts warranty

PEC PEC Type IType I

Liebert

AC Power Medium Exposure TVSS, on distribution and sub-distribution panels, or any medium exposure locations.

Fault Current Rating (AIC): 65 kAICSurge Current Ratings: 100kA, 160kADimensions: 100kA - 6.0”x4.0”x3.0”

160kA - 8.0”x6.0”x4.0”50 Ω EMI/RFI Attenuation: 40 dBStatus Indication: LED, Dry ContactsCertifications: UL 1449, CULWarranty: 5 Years Parts100KA 160KA

PowerSure

Panel Medium ExposurePowerSure

Panel Medium ExposurePEC Type CPEC Type C--100/C100/C--150150

Fault Current Rating (AIC): 14 kAICSurge Current Ratings: 25kA, 50kA, 100kADimensions: 4.72”x4.72”x2.36”

50 Ω EMI/RFI Attenuation: 40 dBStatus Indication:LED, Dry ContactsCertifications: UL 1449, CULWarranty: 10 Years Parts

Liebert

AC Power Low Exposure TVSS, on sub- distribution panels, branch panels, or equipment in low

exposure locations.

PowerSure

Panel Low ExposurePowerSure

Panel Low ExposurePEC Type C-50

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

Single Point Grounding of SystemsVisual check grounding system and system bonding point Conduct risk evaluation (identify vulnerable appliances, equipment, and telephone and computer systems)Surge protection of external servicesAdditional internal SPD at equipmentConductor length short to SPD

Recommended practices