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Surge Protection Devices for LV Systems Australasia A technical overview
© 2007 Eaton Corporation. All rights reserved.
© 2008 Eaton Corporation. Corporation. All rights reserved. reserved.
Last Updated 15/08/07
Who are we, what do we do?
Part of Eaton group. EPQS / Powerware.
Was Total Power Systems, acquired by Invensys / Powerware.
New product design to AS/NZS and IEC standards. Specialising in TVSS / SPD devices.
26 man years of TVSS product development and delivery.
Specialised secure power applications to Navy, Air force, Army, Data Centres.
Specialised TVSS solutions to major commercial operations. Optus, NSW Health, QLD Health, Switchboard manufacturers, Mining industry. Australia, New Zealand, Vietnam, Sri Lanka, Africa, Europe.
54 man years in electrical design and manufacture across 2 people and 5 multinational corporations.
R&D lab Mascot limit 4kA/8kV 8/20us with access to R&D lab China up to 120kA 10/350us. 8/20us. 1.2/50us waveforms.
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Who are we, what do we do?
Part of Eaton group. EPQS / Powerware.
Was Total Power Systems, acquired by Invensys / Powerware.
New product design to AS/NZS and IEC standards. Specialising in TVSS / SPD devices.
26 man years of TVSS product development and delivery.
Specialised secure power applications to Navy, Air force, Army, Data Centres.
Specialised TVSS solutions to major commercial operations. Optus, NSW Health, QLD Health, Switchboard manufacturers, Mining industry. Australia, New Zealand, Vietnam, Sri Lanka, Africa, Europe.
54 man years in electrical design and manufacture across 2 people and 5 multinational corporations.
R&D lab Mascot limit 4kA/8kV 8/20us with access to R&D lab China up to 120kA 10/350us. 8/20us. 1.2/50us waveforms.
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we blow things up for a living… 3
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SPD Industry Myth Lightning strikes can produce in upwards of 200 000 amps of surge current. Therefore 200 000 amps can flow into electrical distribution systems.
Fact! A maximum of 20kV and 10kA gets induced into electrical distribution systems from a lightning event. Voltages and currents in excess of this will cause caus e irreparabl irreparable e damage. damage. Cable Cable insulati insulation on would would fail befor before e the surge could even get into the building.
Source: ANSI/IEEE C62.41
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What is a Surge? A surge is a random, short burst of excess electrical energy to a system. Also referred to as a transient, impulse or spike, these electrical disturbances can damage or even destroy sensitive microprocessorbased equipment. Its duration is in the micro and millisecond time frame.
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Why do I need surge protection?
Electrical equipment design moving to reduce costs and relying on specified mains voltages being maintained to supply standards.
Most equipment is now designed in accordance with regulated surge protection standards (especially Europe).
Utility suppliers can no longer guarantee absolutely error free power.
Trying to deal with excess energy at the final point of entry into your load is the wrong place to deal with it.
Increases the longevity of your investment.
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Where do they come from? 80% of transients are generated from internal sources such as load switching, motors starting up or even turning on air conditioning systems.
Internal
External The other 20% of transients are generated from external sources such as lightning strikes and power company grid switching.
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Causes - Ultimate sources
Lightning strikes
Electrical switching
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Standards.
There is a standard f or everything. No need to re invent th e wheel. Let the standards do the work for you.
Starts with EN LV directives, then flows to surge risk assessment standards, then to equipment standards, then to test standards, then to reporting standards. Some standards you may here about are: ANSI/IEEE C62.41. Low voltage surge protection, waveform, test and current standards and limits. Test waveforms. Each Category / Class type has a different standardised test waveform. 10/350us is Class I 8/20us is Class II short circuit. 1.2/50us is Class II open circuit. 100khz Ring wave is Class III only. Equipment standard will determine the correct waveform to be used.
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Standards.
AS/NZS1768 Region-specific standards - Risk assessment. IEC61643, UL1449 Equipment standards. AS/NZS 3000:2007 Wiring rules. Appendix F.
They do overlap but don’t confuse them.
In Australia, New Zealand and most of Asia, AS/NZS1768, IEC61643-1 and ANSI/IEEE C62.41 are all you will ever need .
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Protection Zones (ANSI/IEEE) Category C (15kA) Point-of-Entry / Service Entrance Category B (3kA) Major sub mains & short final sub circuits Category A (200A) Long final sub circuits & power outlets There are two more categories, which simply extend the Category C Category D (30kA) High exposure such as elevated overhead lines Category E (70kA) Elevated very high exposure & critical load
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Solutions Protection zones – IEC61000 series European standards Class I – Outdoor, “direct strike” Class I devices. Extreme to high risk zone. Class II – Indoor, induced strike Class II devices. High to medium risk zone. Class III – Final circuit, equipment, Class III devices. Medium to low risk zone.
ANSI/IEEE C62.41. U.S. Standards Category E – External elevated supply point. Extreme risk zone. Direct strike. Category D – External supply point. Extreme risk zone. Direct and induced surge. Category C – Point-of-entry High risk zone. Direct and induced surge. Category B – Sub-SWB or intermediate circuit. Medium risk zone. Induced surge. Category A – Final circuit, equipment. Low risk zone. Induced surge.
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Solutions Protection technologies Each Category / Class uses different types of technology in different ways to manage the harmful energy levels .
Surge diverters – MOV, Spark gaps, Gas arrestors. Usually parallel connected.
Surge Filters – creating a a protection zone by limiting current through inductors and using high frequency clipping via capacitors to improve noise rejection. Usually series connected
Each technology has differing electrical attributes and no one technology can be used in all situations.
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Protection Technologies Metal Oxide Varistors (MOV)
Gas Dis charge Tube
Suit all zones except direct strike.
Suit all zones but must not be connected across Line – Neutral or Earth in some circumstances. Has follow current.
Silicon A valanche Diode (SAD) Suits lower risk zones only
Spark Gaps Suits high risk zones only
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Surge Diverters Surge Diverters are parallel connected devices that provide shunt diversion only and are typically used at the point-of-entry to a facility. These devices offer coarse protecti on, making them suitable as the primary defense against power surges.
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Surge Filters Surge Filters are series connected devices that provide fine protection. They are usually installed closer to the load to act as a second line of defense, providing further surge reduction, current limiting & noise filtering for sensitive electrical equipment.
Note: The inductor provides current limiting of surges to load
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Cascading •
SPD’s are designed to work as part of a complete protection system.
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They are typically installed as PRIMARY and SECONDARY devices ( see standards recommendations ). This is known as Cascading and is an important concept in surge protection. No one device can do everything from point of entry to final sub circuit.
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You may have up to 3 levels of protection in a complete system. Ie. A Class I device at high risk point, Class II device at POE and Class III device on GPO.
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In most cases you will need at least 1 x Class II and 1 x Class III device. OR 1 x Class I and 1 x Class II device.
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Protection modes •
Protection modes refers to the way in which the SPD controls harmful energy.
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There are 4 modes: L-N, L-L, L-E, N-E.
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L-N & L-L are referred to as Differential modes.
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L-E, N-E are referred to as Common modes.
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Choosing the right modes for your application depends on your electrical system characteristics. Ie TT, TN, TN-C, TN-CS.
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Most systems in Australia are TN type. Ie Neutral is derived from Earth at the user point of entry. ( commonly called the M.E.N. link ).
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Whatever modes you select the harmful energy must make its way back to Earth SOMEWHERE. So make the control path easy for the energy to get to earth and dissipate.
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System Design Installation issues. 1.
Physical location.
2.
Electrical location.
3.
Safety disconnectors.
4.
Cable length and type.
5.
Earthing.
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Installation Issues Physical location. 1.
As close as possible to Main Switch or metering point – within Main SWB if possible.
2.
Accessible for maintenance – extra isolation switch.
3.
Environmentally benign – no excess moisture or heat.
4.
Personal safety.
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Installation Issues Electrical location. 1.
Locate at a point close to the Main Isolating Switch, allowing close access to all phase and N/PE conductors.
2.
If N/PE is remote from phase conductors, consider extending all conductors to an intermediate point.
3.
Earthing point (for Main SWBs) must be located within a short distance.
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Installation Issues Safety disconnector. 1.
Preferred to use HRC Gg/Gl fuses, not CBs. CBs break down in instant high current waveforms. They can either nuisance trip or be partly damaged causing premature MTBF failure. Fuses are much better at conducting rapid transients. If you must use an MCB then be aware that the total circuit performance may not equal that of the SPD. It will still work, but its not as efficient.
2.
For medium & high-current services (250-3000A), use the maximum fuse as recommended by manufacturer.
3.
For low-current services (<250A), the fuse rating will limit surge capacity.
4.
For very low-current services (<80A), it may be necessary to rely on line fuses.
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Installation Issues Cable length and type. Cable voltage drop is the biggest loss. 1kA/1m ~ 150V @ 8/20us >> Cat C (15kA)/1m ~ 2250V @ 8/20us That’s a lot of stress on the cable BEFORE the SPD gets going. Make the SPD work for you.
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Installation Issues Cable length and type continued. 1.
Cable length (inductance) is the biggest issue.
2.
Multiple, small cables better than one large cable.
3.
Busbars are much preferred, where applicable.
4.
Keep total connection length below 0.5m on any cable and always tie cables tightly together.
5.
Try to keep surge voltage drop to <1kV/cable.
6.
Do not loop extra cable!
7.
Keep input ,“ DIRTY “ power separated from output, “ CLEAN” power. Do not bundle together.
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Installation Issues Earthing. 1.
Site earth must be as good as possible.
2.
Busbars should be used for runs >3m (remember 1kA/m = 1kV!)
3.
Use a ‘star’ (or ‘single-point’) earthing system in all cases -do not daisy-chain earth systems.
4.
Always interconnect sub-SWB earths with adjacent building metal.
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RCD’S in a Surge Circuit
RCD’s are designed to detect current flow between active conductors and earth. When a SPD shunts to earth an RCD will most likely trip. Most L-N shunts should have no impact as long as MEN link is close.
SPD’s should be installed UPSTREAM of any RCD.
Latest wiring rules add another level of complexity to the solution.
There is no avoiding the physics.
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Installation Issues Why we must try hard(er) All SPD systems have appreciable losses. “Weak links” concentrate energy loss. …because lightning doesn’t care.
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Selecting a TVSS product Specify what you really need. Avoid ‘cut and pasting’ other manufacturer’s specifications. Let the SPD equipment standard do the work for you.
What to look for.
“Must have” features.
“Nice to have” features.
Coordinating with upstream and downstream infrastructure.
… BUT DON’T OVERDO IT! 28
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Selecting a SPD product What to look for (questions to ask customers).
Specify a standard. It does the hard work for you. Don’t invent your own. IEC61643-1, AS/NZS 1768, ANSI/IEEE C62.41 are more than you will ever need.
Service voltage and type – 1 or 3-phase, 240/415V, local M.E.N.
What are we protecting? – Specific equipment or the entire building?
Proposed location of SPD – At M.E.N. point or subSWB/equipment?
Maintenance requirements – Repair or replacement shouldn’t require site to be blacked-out.
Likelihood of damage – if SPD is affected by service faults.
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Selecting a SPD product “ Must-have” features (questions to ask customers).
Look for Vpl, MCOV, Inom, Imax, SCW specs. Make sure they are quoted in each mode of operation. Lowest, fastest and largest does not always mean the best. There are traps.
There is a benchmark for each specification.
Service rating determines maximum surge current. Small services (63-80A) are incapable of Isurge > 40kA without the supply fuse(s) rupturing. Do not overspecify.
Common-mode protection is only required for applications remote from the M.E.N. point.
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Selecting a SPD product “ Nice to have” features (questions to ask customers).
Alarms – few people monitor them (except telcos etc.)
Displays – More for show than ‘go’. A clear and concise “Fault” indication is better than taking bets on longevity.
IP ratings – if a customer asks for IP65, ask why – pointing out that SPD equipment should never be ‘stand alone’.
User-replaceable modules – “users” should never work on live equipment. When damaged, TVSS equipment should be replaced in it’s entirety, not 1 phase at a time.
SPD certifications – IEC61643-1 should be adequate!
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Selecting a SPD product Coordinating with upstream and downstream infrastructure (questions to ask customers).
If sizing primary protection, what secondary protection (if any) is intended? Conversely with secondary (sub-SWB) protection.
Service fusing level and fault rating affect SPD capability.
Position, position, position – is the device being protected close to it’s protection? If not, use an auxiliary protector at the load.
For filters, what is the load? If the load has high current distortion, consider using shunt SPD instead.
Filters draw current! Allow for 5% filter current (I.e. 63A filter = 3.15A >> 66.15A supply current OR 59.5A load current.
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SPD product certification
Who cares? (You should. Check for standards compliance and test evidence in specs. IEC standards reflect more closely our low voltage system than UL standards)
Be careful about performance claims. Not all claims are valid or even meaningful.
Why is UL1449 irrelevant in Australia ?
Understanding some of the characteristics:
MCOV, TOV, VPL, Inom, Imax, SCW
Standardised specifications in IEC 61643-1. This standard covers all aspects of safety, test waveform compliance, performance reporting rules etc.
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Load protection guarantee claims
It’s almost impossible to GUARANTEE a failsafe outcome. There are limits to all semiconductor technologies. Such guarantee’s are really about RISK REDUCTION. They also have lots of limiting conditions. And for good reason.
Common installation faults. Devices with multiple ports ( power, data, phone, video etc ) all rely on common earth point VIA the SPD. If even one port is not DIRECTLY connected to the SPD then it will almost certainly fail. RTBM.
Learn to scale your risk. 100kA at a 10A GPO ???
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Good installations vs poor installations
Actually, there are no “really good” installations… … but we can try to make them as ‘good’ as possible.
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SPD Product Range
© 2007 Eaton Corporation. All rights reserved.
© 2008 Eaton Corporation. All rights reserved.
Last Updated 15/08/07
Eaton SPD Products
DIN Rail & Panel Mount Surge Protection Portable Surge Filters
Datalin e & Rack Mount Protection
Premium 3 Phase Diverters & Filters
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Surge Diverters
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Three Phase Surge Diverter MSDi Key Features:
Surge current rating = 60kA/ph Inom & 200kA/ph Imax
Point-of-entry protection
LED Bar graph display on each phase
Enclosed in IP24 painted steel cabinet
Protection fail alarm relay
Surge Category :
Category E, D & C locatio ns
Class II devic e
Application:
Main protection for industrial plants, commercial buildings and process control systems 39
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QuickmovTM Surge Diverter Quickmov TM
SPD50NGi
Key Features:
Key Features:
Fits any QuicklagTM load centre
Surge current rating = 30kA Inom & 60kA Imax
In-built HRC fuse, with the added safety of integrated thermal protection.
Surge Category :
Category C & B locations
Class II devic e
Compact N-E protection solution
Surge current rating – 50kA Inom & 70kA Imax
Class II devic e
Compatible with most switchboards
Application:
Industrial sites, commercial sites, factories, schools and process control systems 40
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Din Rail Surge Diverters SPDi din rail series Key Features:
SPDV60 – 1 Pole 30kA Inom, 60kA Imax
SPD120i – 1 Phase 50kA Inom, 100kA Imax
SPD3i – 3 Phase 20kA/Ph Inom, 40kA/Ph Imax
Alarm contacts as standard
Surge Category :
Category C & B locations
Class II devic e
Application:
Industrial sites, commercial sites, telecommunication, medical and process control systems
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Surge Filters
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3 Phase Premium Power Filter PPFi Key Featur es:
Gear tray versions available
Imax rating up to 240kA
EN certified EMI/RFI Filter
Can be customised to specification
Enclosed in IP24 painted steel cabinet
Panel-mounted mimic display and alarm relay outputs
Surge Category :
Category D, C & B loc ations
Class II device
Application:
Multi-storey buildings, hospitals, IT datacentres and airport facilities. 43
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1 & 3 Ph 40-63A Surge Filter MSFi Key Featur es:
Surge rating Inom = 60kA and Imax = 160kA
Enclosed in IP24 paint steel housing
Available in 40 or 63 Amp ratings
Protection fail alarm relay
Front panel status indicators
Surge Category :
Category D, C & B loc ations
Class II device
Application:
Telecommunication systems, process & control systems, small commercial offices & industrial sites 44
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Compact Surge Filters CSFi
DSFi
Key Featur es:
Key Features:
3-25Amp 240V AC
5-32Amp 240V AC
Surge rating Inom = 10kA and Imax = 25kA
Surge rating Inom = 15kA and Imax = 40kA
Can be used as stand alone solution for units and small offices
Dual stage filter
Can be used as stand alone solution in lightly exposed sites
IP20 painted steel housing
Protection Fail Alarm Relay
Surge Category :
Category B & s ome C locations
Category B & some C locations
Class II devic e
Class II device
Application:
Surge Category :
PLC’s, computer systems, servers, mission critical circuits
Application:
UPS systems, rectifiers, AV 45 45 circuits in clubs & hotels
Portable Surge Filters POD & POD+
SSFi
Key Featur es:
Key Features:
60kA surge protection rating
Handles more than 1 Million surges *(AS1768 Cat A ring wave 200 Amps)
Surge rating Inom = 10kA and Imax = 25kA
Surge suppression and filtering in a single package
Small footprint, modular design
Enclosed in IP50 painted metal housing
6 or 8 extra wide socket spacing
Ideal for data, AV, phone line and Cable TV protection
Surge Category:
Category A lo cations (unprotected or lightly protected sites) Class III device
Ap pli cat ion :
Home, office, entertainment systems, laboratories, computer systems
Surge Category:
Category A lo cations
Class III devic e
Ap plic ati on:
Industrial printers, servers, plug-in UPS and POS systems 46
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Data and Rack Mount Protection Rack Mount
Data & Network
Key Features:
Key Features:
Unique mounting system Rigid steel case
Protects all CAT5 network devices
Protects all 8 wires of a CAT5 cable
Simple to install
PWSF8R-U
22.5kA Surge Rating
Does not effect network traffic
Category A, Class III device
Category A. Class III devices
ECAT6PPC
ERAK16EC5
EMTJPOE60V 47
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Category C / Class II products SPDi SPFi
Category Categor y C (15kA)
MSDi
MSFi
Quickmov
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Category B / Class II products SPDi
Category B SPFi
CSFi
(3kA)
MSFi
DSFi Quickmov 49
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Category A / Class III products SSFi
SF8RU
Category A (200A)
ERAK16EC5 EMTJPOE60V 50
POD
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If you need assistance or advice on design or specifications:
Mike Hale. 9693 4350
[email protected] Ryan Nguyen. 9693 9459
[email protected]
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