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Surge Protection Devices for

Facility EngineersAnd Electricians

Peter Walsh, PE

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Today’s Information

● History of SPD Protection

● Why Specify an SPD?

● Codes and Standards

● Specifications

● Q & A

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What Products are We Discussing Today?

Specification Products

● STXT Intended for Service Entrance Protection

● STXP Larger Distribution Panels / Branch Panels

● STXR Branch Panels, Control Panels, Equipment

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● STT ● End use equipment● Listed Type 1 ●OEM or Retrofit Applications

● ST Pluggable and Modular- OEM Applications● End use equipment● UL Recognized●OEM Applications

What Products are We Discussing Today?

General and OEM Products

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What’s Inside?

Arc Shield:Provides isolation of electrical contact during and after low level or short circuit faults

TPMOV: Patented thermally protected MOV

Eutectic Solder:Melts away and releases arc shield when the MOV senses thermal runaway

MOV Disk

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How the Surge-Trap Operates

Surge Trap in normal operating conditions or as over voltage condition first begins.

Surge Trap as thermal protection contact begins to operate and arc shield begins to move.

Surge Trap as thermal protection contact completely separates and arc shield continues to isolate.

Surge Trap in open state, with arc shield completely closed and visual indicator present.

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History of Surge Protection

Secret Magic Until Mid 1980’s– Not any way to verify marketing claims– Any manufacturer could claim anything– More than 25 small companies making products and claiming theirs

was the only one that had the most important “X” performance– Most of the products would burn up under certain conditions– Switchgear companies faced large claims when the SPDs failed

internally to their switchgear

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History of Surge Protection

Responsible SPD Manufacturers and Switchgear Companies agreed to cooperate to develop UL Standard 1449– Original edition required a least minimal safety tests

Mersen (Ferraz Shawmut) started to develop the TPMOV responding to new OEM interest in safety (We have 12 years experience making TPMOVs)Battle lines were drawn between the old-school anything-goes SPD manufacturers and the safety conscious performance verified companiesEventually the industry adopted third party (UL) verified testing for safety and performance

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What Is a Surge?

● High amplitude at least 2X greater than the normal voltage with short duration. It can be thousand of volts

● Can be positive or negative polarity● What the difference between transients and noise?

● Transient: Greater than 2X system RMS voltage●Noise: Less than 2X system RMS voltage

Millionths of second

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What Does a Good SPD Prevent?-Insulation Breakdown

500% X 120V RMS X 1.414 = 850V Peak for 0.01 cycles

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Surge Greater than the Insulation Rating

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Overview of the Risk

Never before have we seen so many Drives, PLC’s, Microprocessor based machine controls on the manufacturing floor.To prevent damaging voltage problems proper surge protective devices need to be used in a cascaded method throughout the facility.It’s a common misunderstanding SPD’s are used for lightning protection while in reality 80% of all overvoltage problems are caused within a facility from equipment. (Commercial, Industrial, Institutional)

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Effects of Surges?

Electronics can’t tolerant Surges- Three Ds

Disruption - Lockups, Downtime & Interruption costs, Computing / operating glitches and errors

Degradation – To electronics, Damage to motor insulation

Destruction - Failed electronics, ballasts, motors, controllers

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MOV - Metal Oxide Varistor

Varistor - variable resistorSemiconductor; generally zinc oxideConnects parallel to load (not series)Thickness determines clamping voltageDiameter determines current capacity MOV symbol

50 kA

10 kA

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MOV - Metal Oxide VaristorAt Low voltages: very high impedance, ≈109ΩThreshold voltage: resistance approaches 0Ω– Overvoltage diverts through MOV as current– Voltage is “clamped” as energy is transferred to other side of MOV(s)

MOV does not ‘absorb’ surge, however, I2R heat is retainedBidirectional – Operates same for positive or negative surgesCreates a momentary short-circuit to pass transient energy to earth; analogous to water heater pressure relief valve

+-+ -

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SPDs are parallel connected devices that sense overvoltage conditions and create a momentary path to ground redirecting harmful overvoltage energy.

Think of it as a pressure relief valve in a water system, relieving the pressure then resetting itself but in an electrical system.

SPD Operation and TPMOV Technology:

SPD

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Codes & Standards changes are driving an industry

UL 1449-3rd (Sept 2009) edition has significant product testing changes that has caused an industry to redesign most of their products.

The changes are difficult to pass and have created third party verification of product claims.

Products that comply are required to have the newer UL holographic label on the product.

We’re in an education stage with electrical inspectors and insurance inspectors

UL 3rd edition is only product compliance that should be specified

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Why did UL revise the standard?QA& Reported catastrophic product failures of surge protection

devices derived an initiative at UL to revise its UL 1449 2nd

Edition safety standard.

Pictures of non fused and non thermally protected MOV based surge products. Products were tested under the new requirements of UL1449. The MOVs saw sustained over voltage conditions and were forced into thermal runaway. Molten metal oxide was expelled, plastic case ruptures occurred and significant black smoke was present during testing.

Internal versus External SPDs?

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UL 1449 THIRD Edition

SPDTVSSSurge Arresters

●New Voltage Protection Ratings (VPRs) replacing old-style …Suppressed Voltage Ratings (SVRs)

● New Endurance In nominal ratings

●New safety SCCR values

●New Application SPD Types: Types 1, 2, 3 & 4

Combines TVSS and Surge Arresters into one UL Standard, UL 1449 3rd Edition renamed: Surge Protective Devices (SPDs)Effective: Sept 29, 2009

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What Does the Management Want?

Safety– UL Listing– Sufficient SCCR value

Protection of Equipment from Surges– Low Voltage Protection Rating VPR

Endurance– High Nominal Current Rating In

Independent third party testing of marketing claims– UL Testing and Listing

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Protective Test Format Changed to VPRNew Testing uses Six (6) Times More Energy

Old – 6kV / 500ASuppressed Voltage

Ratings (SVR)

New – 6kV / 3,000A Voltage Protection

Ratings (VPR)

500A

3000A• As a surge amplitude goes up,clamping voltage goes up too

• Specs become obsolete• Need new VPRs in specs

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UL 1449 Protective RatingsVoltage Protection Ratings (VPR’s)3,000A test impulses

– Uses 6” lead lengths from outside of enclosure

– UL specified waveshapes– UL specified oscilloscope

settings & probesDirectly comparable resultsPosted on every SPD’s UL labelDiscrete VPR categories of 500, 600, 700, etc….voltsVerifiable on UL.com

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UL 1449-3 Endurance

Nominal Current Testing – In - (Nominal Discharge Current)- Duty Cycle Testing-15 of 8x20μs surges through every mode of three samples used for VPR testing-- New Concept to USA – (Originated from IEC 61643)

Type 1 – 20kA or 10kAType 2 – 20kA, 10kA, 5kA or 3kAType 3 – 3kAType 4 – Based on intended usage as Types 1, 2 or 3

UL 96A Master Label requires 20kA In from Type 1 or Type 2 SPD

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These Ratings Have Similar Units

Nominal In - (Nominal Discharge Current)-Mersen Spec Grade Devices are 20kA

SCCR-Mersen Spec Grade Devices are 200kA

Surge RatingMersen Spec Grade Devices are 50kA, 100kA, or 200kA+

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Some Terms Not Fixed Yet

● Joule ratings were never defined by UL, IEEE, or industry• Although the Joule game appears to be over, be aware:• No standard exists and never has, no test program or

measurement exists • Many ways to manipulate ratings – be careful• Use the new data from the new UL testing

● Surge Ratings are not Defined 50kA, 200kA, 400kA • Historically it was the MOV Supplier Rating• Many companies are stretching their MOV Ratings

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How Does One Select SPD Maximum kA Ratings?Subjective & Delicate:• Sometimes Based on Ampacity of Gear:

- Presumption that larger gear has more valuable equipment

Larger

Panel Ampacity: SPD kA:4000A-3000A: 400kA-300kA3000A-2000A: 300kA-250kA2000A-1200A: 250kA-150kA1200A-800A: 200kA-100kA800A-400A: 150kA-50kA400A-50A: 100kA-50kA

Careful: 1.) More valuable equipment might be on smaller panels 2.) Surges do not differentiate based on panel size

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Verifying at www.UL.com

ClickCertifications Category Code #’s:

VZCA for SPDs

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SCCR labeling consistent with location in distribution system:

285.6 - “The SPD shall be marked with a short circuit current rating (SCCR) and shall not be installed at a point on the system where the available fault current is in excess of that rating. This marking requirement shall not apply to receptacles.”

2008 NEC – Key Points

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● “285.5 Listing. An SPD shall be a listed device.”

● Note: UL will always have a UL Holographic label showing “SPD” on a SPD Product that is UL Listed

NEC – Key Points

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2008 NEC – Key Points

“285.3 Uses Not Permitted. An SPD shall not be installed in the following:

On ungrounded systems, impedance grounded systems, or corner grounded delta systems unless listed specifically for use on these systems.”

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OEMEquipmentRetrofit

NEC Locations for SPD Type:

UL Recognized SPDs Are Only for OEM Installation

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Example Lightning Protection System UL 96A

Lightning Rod

Conductor connecting all metals and grounds per UL 96A and NFPA 780

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• XR Series , Listed Type 1 SPD

• End Use Equipment

• HVAC – 4X enclosure

• XT Series –Listed Type 1 SPD

• Service Entrance Gear

• Main Distribution Panel Board

• ST Series –UL Recognized Type 4 SPD

•Pluggable and Modular

• Inside Control Panels

• OEM based equipment

• STT Series – Listed Type 1 SPD

• End Use equipment

• Indoor use

• XP Series – Listed Type 1 SPD

• Distribution Panels,

• Motor Control, Automation Control

• Larger Equipment, Drives

Applications

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Applying & Selecting SPDs

Effective Facility Protection - Factors to Consider Positively ID the Electrical System (480V 3-phase isn’t enough)Proximity in Facility (Service is different than downstream)Modes of ProtectionCascading SPDsLocating & Placement of SPDsInstalled Clamping Voltage (Short Leads)Redundancy = Longevity (kA ratings for redundancy & longer life – to a point)Power + phone/data/network = Complete Protection

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Engineering Factors to Consider

Point of Application– Specific piece of equipment– Usually, a modest SPD works fine– Protecting upstream panel usually works better and protects other

equipment at same time-Cascading

▀ Whole Facility-Tends to be a coordinated approach

by controlling ‘outside’ surges coming ‘in, and ‘inside’ surges, moving throughout

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Cascade Protection

Trans

MeterSvc. Disc.

Main Panel

Type 1

10m (30feet)

Type 2

Type 3NEC & UL Types

Dist Panel

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Noise Filtering

Textbook Low-Pass filterSimple, first order L-N capacitive filtersUL1283 & MIL STD 220B Beware:– Ratings often derived by

including 100’ of lead length– Impressive names for basic

functionalityAll “track” sinewaveAll “fill in” notches

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Diagnostic Features

LED indicators) – sometimes one per unit, or one per phase (Some brands are idiot lights, and/or do not monitor all MOVs)

Audible Alarm – makes sound if problem

Form C Dry Contact –changes state to trigger indication elsewhere (building management)

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XP

XT

XR

Why Mersen SPDs:

• TPMOV- Superior Diagnostic Monitoring

Too many SPDs have insufficient monitoringExamples:• LEDs illuminate when power is present• Only a portion of MOVs are monitored• Few SPDs monitor N-G (because its hard)• SPD can be mostly dead, yet customer thinks

it’s A-OK good (especially SPDs with longer warranties)

TAC switch on each individual MOV – triggered by mechanical contact with slide gate

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Warranty on Specification Grade SPD Products

●STXT 10 Year Specific Warranty

●STXP 10 Year Specific Warranty

●STXR 2 Year Specific Warranty

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● All Products UL Listed to UL 1449 except Pluggable and Modular which are Recognized to UL 1449

● Full Range of Products● Smallest Footprints available● TPMOV Technology Provides

● Industry leading performance● Enhanced personnel Safety● Product Reliability● Eliminates Need for Upstream OCP● Arrestor Grade MOVs● Diagnostic Monitoring

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Today’s Information

● History of SPD Protection

● Why Specify an SPD?

● Codes and Standards

● Specifications

● Q & A

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Questions?

Surge Protection Devices for

Facility EngineersAnd Electricians

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Your Electrical Protection Resource

Peter Walsh, PE -Senior Field Engineer