SURGE ARRESTER RS-485 / RS-422

FOR ALL RS-485 BASED BUS SYSTEMS SUCH AS MODBUS RTU, DMX, EKEY, PROFIBUS

Newly designed protection element for overvoltages and overcurrents with THREE protection levels. The protection cascade combines a high discharge capacity with an extremely short response time and ultra-fast current limiting, resulting in an outstanding protection effect.

NEW! Surge arrester and overcurrent protection in one module, certified for 5,000 amps (pulse class C2, tested at 10,000 V).
NEW! clamping voltage only 10 V on the device side (after 1 µs)
NEW! combination of three stages with a total of 11 protection and flashover paths
NEW! PE connection with very low contact resistance for uncut and low-impedance connection with 2.5 mm²
NEW! Including two sets of terminals green, grey and orange for three-pole connection of D+, D- and GND
NEW! now also available as SparPack or SuperSparPack with addition (one piece for five pieces or two pieces for 10 pieces)

YOU WILL BENEFIT FROM

• Very low protective voltage: Three-stage module for a protective voltage of only 10 V on the device side after 1 µs
• Including overcurrent protection: Module also includes overcurrent protection (limited to 200 mA)
• Independent of protocol: Suitable for all RS-485-based protocols such as Modbus RTU, DMX, Profibus
• Optimal protection of servers: Particularly suitable for the protection of Timberwolf servers / Loxone servers / RS-485 extensions
• Solid protective earth connection: PE connection with low impedance that allows uncut installation
• Overall protection: Due to the combination of short response time, low protection level and fast current limiting, this protection element minimises the load on the protected devices in the RS-485 / RS-422 based bus system as well as on the insulation on the device side to practically zero.

AREAS OF APPLICATION

DIN / IEC 61643certified lightning and surge protection system, tested for use in RS-485 / RS-422 bus systems and thus suitable for :

• DMX: any DMX bus system, DMX connections Timberwolf Server, Loxone DMX Extension.
• Modbus: Modbus connections Timberwolf Server, ElabNET Modbus RTU Extension, Loxone Modbus Extension
• RS-485: any other RS-485 interface, RS-485 connections Timberwolf Server, Loxone RS-.485 Extension
• Profibus: any Profibus system
• ekey: all ekey systems (ekey Home, ekey Multi, ekey Net)

KEY PERFORMANCE FEATURES

• Application: Module for protecting the RS-485 / RS-422 installation against overvoltage and overcurrent
• Design: High discharge capacity and low dynamic resistance thanks to parallel-acting protective gaps
• Protection levels: Innovative three-stage surge arrester including fast overcurrent protection for short reaction time and best protection capacity
• Number of protective paths: Eleven protective paths, consisting of six bidirectional flashover paths plus two protective paths via diodes plus three protective paths via current limiters
• Response time: Less than 40 ps
• PE connection: Low-impedance PE connection for uncut connection to lightning equipotential bonding with 2.5 mm².
• Protection level on the bus side between D+ and GND: < 616 V (for pulse class C2, 10,000 V (1.2/50 µs) / 5,000 A (8/20 µs) - on the unit side, however, only for 1 µs, thereafter terminal voltage 10 V
• Protection level on the bus side between D- and GND: < 605 V (for pulse class C2, 10,000 V (1.2/50 µs) / 5,000 A (8/20 µs) - on the unit side, however, only for 1 µs, afterwards terminal voltage 10 V
• Certified: This surge arrester for information technology systems has been certified according to IEC 61643-21-2001 + A1:2009 test C2 for "fast rising edge" and corresponds to arrester type 2.
• Made in Germany
  

RECOMMENDATION FOR DESIGN

• Due to the different protective character of the two module connections (bus side vs. equipment side), we recommend connecting the long part of the bus installation on the bus side and the short part - especially for protecting servers, PLCs, gateways, etc. - on the equipment side of the module.
• The bus can be protected with several such modules, in which case only the bus side should be connected and the RS-485 / RS-422 bus should be routed past the module.
• For very long buses, we recommend one such module every 50 m. Here, too, the module is to be connected only with the bus side facing the RS-485 / RS-422 bus cabling.
  

COMPATIBILITY

• PLCs, gateways, devices with RS-485 / RS-422: This module is compatible with all RS-485 / RS-422 bus systems, regardless of the protocol. It can be used with all servers, PLCs, gateways and devices with this interface.
• Timberwolf Server: This module is compatible with the RS-485 interfaces on the Timberwolf Server 950Q and 960Q.
• Timberwolf Server Extensions: This module is compatible with the Modbus RTU Extension and the DMX Extension.
• Loxone Extensions: This module is compatible with the Loxone DMX Extension, Loxone Modbus Extension, Loxone RS-485 Extension.

The capacitive load of the two data lines of the RS-485 / RS-422 bus by this surge arrester is approx. 75 picofarad, which corresponds to the capacitive load of less than 10 m bus line.

FREQUENT QUESTIONS AND ANSWERS

• What is the function of the BlitzART RS-485 / RS-422 surge arrester?
  The BlitzART RS-485 / RS-422 surge arrester reduces the consequences of a near and far lightning strike by fast equalisation between all connected cores with the lightning current potential equalisation and an almost complete interruption of the current flow between the bus and the device side of the module. As a result of the equalisation and the blocking, voltages are considerably reduced and thus components and insulation of the devices and the bus lines are protected.
  
• Reduced means "not complete"?
  No system in the world can offer 100% safety. However, depending on the design, it is possible to significantly reduce the probabilities of damage caused by lightning. This BlitzART RS-485 / RS-422 surge arrester, with its extremely short response time and low protection level, is able to offer the best available level of protection for RS-485 / RS-422 systems. Especially when these arresters are installed at several points in the system. On the device side of the module, the surge voltage is virtually eliminated. Even with a massive surge voltage of 10,000 V and 5,000 A (8/20 µs) on the bus side, the protective voltage on the device side is only 10 V at a few mA after 1 µs. This eliminates any damage to the RS-485 / RS-422 components on the device side.
  For maximum effectiveness of the arresters, we recommend supplementing the low-voltage part of the system with arresters for power engineering systems type 1 and type 2 (or combination arresters type 1/2). Consult a specialist company for this.
  
• What are the planning and installation recommendations for the best protection?
  Please plan one or more modules per RS-485 / RS-422 bus, depending on the scope of the bus system.
  
  Install one module in close proximity to the protection of the master system, i.e. the PLC, gateway, server or extension. Loop the RS-485 / RS-422 connections directly through the device side of the module to the RS-485 / RS-422 bus (which you connect to the bus side).
  
  For a longer bus (more than 50 m), we recommend installing another module in the middle of the bus. In this case, connect the RS-485 / RS-422 bus only to the bus side of the module. RS-485 bus systems do not support branches, so do not connect devices to the device side of the modules that are installed "in the middle of the bus".
  
  For very long RS-485 buses, install another module every 50 - 100 m (connect only the bus side).

Most important additional measure: Have internal lightning protection (type 1 and type 2 arresters) installed for energy networks.

• The RS-485 / RS-422 bus is galvanically isolated from everything else as a SELV system and the lines are shielded. How can an overvoltage, a lightning strike destroy this?
  Nothing is perfect, not even foil shields. Therefore, capacitive and inductive coupling of the lightning energy is possible. In addition, the insulations are designed for 4,000 V, but lightning generates voltages of up to several hundred thousand volts. Therefore, all insulations are at risk, especially in close proximity / contact with PE, neutral and all external conductors. We recommend separate, separate cable routing of all lines of information technology systems, as well as signal and bus lines of power supply lines. Separate metallic and closed cable racks or channels for cable routing would be optimal.
  
  There is a danger with applied shielding, especially if it is applied on both sides. In the event of a nearby lightning strike, the lightning voltage is conducted through the foundation earth electrode into the building and thus to the PE of the entire building. The shield is under voltage and may also have to compensate for currents. This stresses the shield itself and the insulation inside the bus lines. This surge arrester for RS-485 / RS-422 has a low-impedance PE connection and compensates for potential differences. Please connect the PE connection of the protective modules to the same PE terminal block to which the shield is applied. From this terminal block, a length of at least 2 m to the PAS should be maintained (so that, purely in terms of time, a type 2 arrester can switch through first).
  
• What endangers the insulation?
  Ein Blitzschlag bedeutet eine Entladung zwischen Wolke und Erde über eine Luftstrecke, die kurzzeitig leitfähig ist. Ausgehend von dem Blitzkanal als stromdurchflossener Leiter wird ein elektrisches und ein magnetisches Feld um diesen herum erzeugt. Diese Felder koppeln kapazitiv und induktiv in Leitungen und Leiterschleifen ein und ändern die Potentiale in allen metallischen Leitern im gesamten Gebäude. Die nahe Erde kann nur einen Teil der Blitzenergie aufnehmen. Etwa die Hälfte der Energie wird durch den Fundamenterder über PE in das Gebäude geleitet. Damit steht bei einem nahen Blitzschlag die Potentialausgleichsschiene und damit der gesamte PE über den Fundamenterder unter einem sehr hohen Spannungspotential von mehreren zehntausend Volt. Diese Potentialunterschiede wollen sich untereinander und zur fernen Erde in der über den Netzanschluss erreichbaren Trafostation (und je nach Netzform auch zur Erde der benachbarten Gebäude) hin ausgleichen. Um diesen Weg nehmen zu können, versucht die Blitz
  
• How does this BlitzART surge arrester protect?
  The different potentials that form in metallic conductors when lightning strikes close by want to equalise. The equalisation takes the path of least resistance. This BlitzART arrester offers the surge voltage a simple path by creating a massive short-circuit almost immediately in the event of a sudden voltage increase, through which the potentials can equalise. The BlitzART surge arrester involves the three connected wires and PE and creates a short-circuit between all four connections. This offers the surge voltage an immediate and low-impedance equalisation, so that potential differences are considerably reduced and insulation and components are thus protected.
  Such an overvoltage event is already completed after twenty millionths of a second in this area of the cabling. During this short time, the components convert several thousand W of heat. A lightning bolt has an average energy of 280 kWh, about one tenth of which is converted on the ground and in the installations.
  
• Why are there 11 switching, protection and flashover paths in this BlitzART surge arrester?
  Each component for surge protection has its own characteristics with regard to reaction time, voltage limitation, tripping voltage, maximum voltage, discharge capacity, heat absorption, leakage current, capacitance and polarity. There is no component that is the leader in all these characteristics; often one parameter is very pronounced, while others are less so. So that we did not have to make a compromise with this BlitzART surge arrester, we combined several components with a total of 11 protection and surge paths in a three-stage cascade in such a way that components with the shortest possible reaction time complement each other with components with high discharge capacity amperes. In this way, we achieve a previously impossible level of protection.
  
• I have removed the assembly from the module. On the underside of the board I see nine component pins that are not soldered. Has something been forgotten here?
  No, these nine pins belong to the high-current PE connection. Over the four edges of each of the nine pins, the component is homogeneously cold-welded to the through-platings of the board by means of a press fit in the factory at 36 connection points. This connection technique is mechanically very stable (pull-out force 900 N), at the same time very low-impedance (less than 200 µOhm), permanently gas-tight and can carry high currents (500 amperes permanently). With this - and the crimped cable lug for uncut PE connection with high cross-section - we achieve a low-impedance PE connection.
  
• Are there any tips for the connection to PE?

1. Same PE terminal blocks: If a surge arrester protects devices that themselves have a mains voltage connection with a protective earth conductor (for example, a power supply unit for supplying the bus master and its server), then the PE connection of the surge arrester should be routed to the equipotential bonding with the same or lower impedance (than the connection of the protective earth conductor of the device that is also to be protected to the equipotential bonding). We therefore recommend routing the PE connection of the surge arrester on the shortest path to the same PE terminal block to which the protective earth conductor of the power supply unit to be protected is connected (if it is such a power supply unit).
   The same applies if the shield of the bus cabling (usually not recommended, but may make partial sense for interference suppression) has been connected to PE. In this case, the PE of the surge arrester should be routed to the same PE terminal block to which the shield has been connected. Such shield connections should be tied over the entire shield circumference with special clamps; the often braided braids are electrically unfavourable for discharging transient overvoltages).
   
2. Ordentliche Arbeitsweise: Führen Sie den PE-Anschluss bitte mit größter Sorgfalt aus. Verquetschen Sie ausschließlich diejenigen Leiterklassen im richtigen Querschnitt, die für den verwendeten Quetschkabelschuh jeweils zugelassen sind und verwenden Sie hierfür nur die korrekte Quetschzange (wenn Sie den mitgelieferten Quetschkabelschuh verwenden. lesen Sie bitte in den technischen Daten nach). Schrauben Sie die Mutter am Anschluss gut fest (Anzugsmomente in den technischen Daten beachten). Verlegen Sie die Leitung auf dem kürzesten Weg zum PE-Klemmenblock und schrauben Sie die Leitung auch dort ordentlich fest (Angaben des Klemmenherstellers beachten, insbesondere zum Gebrauch von Adernendhülsen und zu den für diese Klemme erlaubten Querschnitte). Vermeiden Sie unbedingt eine räumliche Schleife im Gebäude zu bilden (um Induktion bei Blitzschlag zu vermeiden) und wickeln Sie keinesfalls die PE Leitung um etwas herum (keine Spule bauen). Es ist wichtig, dass diese Anschlüsse mechanisch fest, dauerha

• I have external lightning protection, do I need this BlitzART surge arrester at all?
  Yes, absolutely. If an external lightning protection system ("lightning conductor") is present, an additional internal lightning protection system is always required (in accordance with the corresponding standards). After all, the lightning is conducted from the lightning conductor directly via the foundation earth electrode into the building onto the equipotential bonding rail. From there, the overvoltage attempts to pass through to all neighbouring metallic conductors with a lower potential. Only an internal lightning protection system prevents this by short-circuiting all metallic conductors with each other. This BlitzART surge arrester is an important component of such an internal lightning protection system on level C2 / Type 2 and takes over this task for the connected bus and its server. This is a supplement to the coarse and medium protection system according to Type 1 and Type 2, which must also be installed and which must be installed by an expert for lightning protection systems.
  
• Isn't surge protection built into the units?
  Richtig, in den meisten Geräten sind kleine Schutzdioden eingebaut, üblicherweise bestehend aus einem einzigen Element. Diese Schutzelemente sind für das Bestehen des gesetzlich vorgeschriebenen Surge-Tests dimensioniert. In diesem Test fließen kurzzeitig nur geringe Ströme von 10 bis 24 A. Das ist bei weitem nicht ausreichend, um Blitzteilströme zu tragen. Zudem wirken diese eingebauten Schutzelemente nur zwischen den BUS-Leitungen (Querspannung), jedoch nicht gegenüber PE (Längsspannung). Damit werden die Isolationen von Servern SPS, Spannungsversorgung und die der Busleitungen nicht geschützt. In den meisten Fällen wird bei direktem oder nahem Blitzschlag die Überspannung durch PE (und womöglich über die Außenleiter) in das Haus geführt. Daher muss für optimalen Schutz der Isolierungen und Bauteile ein Ausgleich aller Leitungen untereinander und mit PE erfolgen, damit sich alle Anlagenbestandteile auf dem gleichen Potential befinden. Dieser BlitzART Überspannungsableiter kann etwa das fün
  
• When does the BlitzART surge arrester trip?
  The fine stage starts to conduct from about 15 V, the gas voltage arresters ignite from about 150 V and a rate of voltage rise that is typical for surge events with a correspondingly steep rising edge. The overcurrent limiters act from 200 mA
  
• Will a BlitzART surge arrester be destroyed by lightning?
  No, usually not, this module can withstand lightning currents of up to 5,000 A. If this should ever happen, please let us know, we will often find an accommodating compensation.

TECHNICAL DATA

Type 2 surge arrester for all protocols via RS-485 bus systems with three-stage protection system with current flow cut-off to the equipment side.

This surge arrester can discharge 5000 amperes (8/20 µs, pulse category C2, fast rising edge). In addition, this protection system is equipped with the innovative ElabNET Current-Cut technology (self-resetting high-speed fuse 1µs), which provides additional protection even against low overvoltages (e.g. short-circuit with 24 V due to wiring error).

This BlitzART protection system is thus a combined protection system consisting of a very powerful type 2 surge arrester plus a very sensitive overcurrent protection (200 mA / 1 µs). Within one microsecond, the overcurrent protection switches off a possible damaging current to the side of the unit which could still occur due to the remaining protection level of the other two stages. The reset after the overcurrent event takes place automatically within one millisecond.

This short-circuits overvoltages, compensates for potential differences and additionally separates remaining overcurrents. Due to this special combination, the achievable device protection is at least ten times better than conventional protection systems without this third protection level.

Intended use / range of application / intended use:

This RS-485 / RS-422 surge arrester of category C2 / type 2 according to IEC 61643-21 is intended for installation in distribution cabinets and junction boxes in dry residential and business premises, control cabinets in industry and automation systems. It serves as a surge arrester between electrical conductors of the RS-485 / RS-422 bus system and the equipotential bonding rail in case of direct and near lightning strikes as well as overvoltages from switching operations and discharges the partial lightning current into the earthing system. We recommend the combination with a surge arrester for power networks type 1 and type 2 as well as the use of several of these RS-485 / RS-422 BlitzART modules in the system.

This module is designed for all RS-485 / RS-422 bus systems without restrictions.

• Surge protection device as part of the internal lightning protection for RS-485 / RS-422 based bus systems
• Arrester for overvoltages from galvanic, inductive and capacitive coupling as a result of close lightning strikes (atmospheric overvoltage)
• Arresters for overvoltages due to distant lightning strikes (e.g. in transmission networks)
• Arresters for overvoltages due to switching operations in low, medium and high voltage networks (switching overvoltage)
• Self-resetting, rapid overcurrent protection device, thus protection even against low overvoltages (e.g. 12 V on the bus-side connections in case of incorrect wiring).

Note: This module has three protective effects, which differ depending on the connection side. The power stage acts on the bus side of the module and can compensate or discharge 5,000 amperes. Both connection sides are connected via a three-pole overcurrent protection stage. The downstream ultra-fast fine stage initially acts on both connection sides at the start of an overvoltage event; once the overcurrent protection stage is activated, the current flow between the two sides is limited, so that the voltage compensation of the fine stage only has an effect on the device side (as long as the event lasts) and drastically reduces the terminal voltage there again. For details, please read below under Function and Effect

• Bus side: After all three protection stages have been triggered, the gas voltage arresters act on the bus side and equalise up to 5,000 amperes.
• Device side: After all three protection stages have been triggered, the overcurrent protection reduces the current flow between both sides to 200 mA per path, the fine stage on the device side now reduces the protection voltage to 10 V.
  

Overview of the included protection technologies

• Protection scope: Three-stageprotection of the connected devices and power supplies as well as the insulation of lines against overvoltage from near and far lightning strikes, against overvoltages caused by switching operations as well as protection between bus and device side against overcurrent already from 200 mA. Thus also limitation of equipotential bonding currents via bus and (especially) GND lines.
• Total number of flashover paths: Eleven bidirectional flashover paths.
• Number of gas voltage arresters: Six flashover arresters via double-chamber gas voltage arresters (specified by the manufacturer as 20,000 amperes).
• Number of TVS diodes: Two flashover paths via ultra-fast bidirectional TVS protection diodes (response time specified by the manufacturer as 1 ps)
• Number of current limiters: Three overcurrent protection paths with fast, self-resetting current limiters (limiting in 1 µs, resetting 1 ms)
• Type of surge arrester: Type 2
• Certified current discharge: 5,000 amps at 8/20 µs (increased current load according to pulse class C2, fast rising edge)
• Low-impedance PE connection: PE connection with particularly low contact resistance, pre-assembled with washers, spring washer, nut and crimping cable lug for uncut connection to equipotential bonding up to 2.5 mm².
• Overcurrent protection: Current-Cut technology, based on three ultra-fast, self-resetting fuses in all line paths, tripped already at 200 mA within 1µs, disconnects the connection between bus and device side of the module
• Automatic reset: reconnection between bus and device side within 1 ms after overvoltage or overcurrent event
• PE connection: Pre-assembled with washers, spring washer, nut and crimp cable lug (DIN 46234) for connection to equipotential bonding up to 2.5 mm².
  

Operating range

• Nominal voltage/ maximum continuous voltage D+ to GND: -7 V to +14 V
• Nominal voltage/ highest continuous voltage D- to G ND: -7 V to +14 V
• Leakage current D+ to GND: < 1.5 µA
• Leakage currentD- to GND: <1 .5 µA
• Leakage currentD+ to D-: < 1 µA
• Insulation resistance at nominal voltage: > 6 MOhm
• Capacitance D+ to GND: 75 pF
• Capacitance D- to GND: 75 pF
  

Protection level (for overvoltage 10,000 V and 5,000 amperes)

• Data lines, D+ to GND: < 616 V (at pulse class C2, 10,000 V (1.2/50 µs) / 5,000 A (8/20 us)
• Data lines, D- against GND: < 605 V (for pulse class C2, 10,000 V (1.2/50 µs) / 5,000 A (8/20 us)
• Currentlimitation: The remaining damaging current from the protection level is switched off by current cut after 1 µs
• Pulserecovery, D+ to GND: <0.72 ms (measured at 2,000 V (1.2/50 µs) / 1,000 A (8/20 us))
• Pulse recovery, D- to GND: <0.84 ms (measured at 2,000 V (1.2/50 µs) / 1,000 A (8/20 us))
  

Test standards and certification

• Certification: According to EN 61643-21:2001 + A1:2009 + A2:2013: according to pulse class C2 at 10 kV (1.2/50 µs) / 5 kA (8/20 µs)
• Test laboratory: DEHN Prüf- und Testzentrum, Neumarkt, accredited according to DIN EN ISO/IEC 17025:2018 by the German Accreditation Body DAkkS
  

Connections on bus side

• Bus: triple plug-in terminal Wago 243 with four connections each per potential and test opening
• Permissible conductor class: solid conductor with diameter 0.6 - 0.8 mm (conductor class 1 according to DIN/IEC 60228)
• Stripping length: 5-6 mm
• Overvoltage protection: The overvoltage protection by short-circuiting acts against the bus side of the module or PE, the device side is additionally disconnected by the overcurrent protection.
  

Connections on the unit side

• Bus: triple plug-in terminal Wago 243 with four connections each per potential and test opening
• Permissible conductor class: solid conductor with diameter 0.6 - 0.8 mm (conductor class 1 according to DIN/IEC 60228)
• Stripping length: 5-6 mm
• Overcurrent protection: Current-cut overcurrent protection limits the current between the bus side and the device side of the module
  

Potential equalisation connection

• PE connection: Low-impedance connection between module and lightning current equipotential bonding by means of cold-welded connection terminal, spring-loaded screw connection, gas-tight crimped cable lug and uncut cable routing with 2.5 mm².
• Connection terminal: Terminal with very high current carrying capacity, best long-term reliability due to permanently gas-tight connection of the terminal to the assembly by 36 homogeneously cold-welded contact points with a pull-out force of 900 N, thus low contact resistance with < 200 µOhm,
• Screw connection: pre-assembled connection with washers, spring washer, nut and crimping cable lug (according to DIN 46234)
• Crimpable conductor class: stranded, fine-stranded and fine-stranded conductors with 2.5 mm² (recommendation: H07V-K2.5 gn/ge; conductor classes 2, 5 and 6 according to DIN/IEC 60228)
• Crimping pliers: Please use crimping pliers for uninsulated crimping cable lugs in accordance with DIN/IEC 46234.
• Stripping length: 5 mm
• Connection thread: M3
• Maximum tightening torque: 0.5 N m
• Breaking torque of grub screw: 1.5 N m
• Notes for larger cross-sections: The crimping cable lug can be exchanged by you, so that a larger cross-section or connection of solid conductors is possible.
  

Protection class module

• Protection class: III / SELV (according to EN60730)
• Protection class: IP 00 (according to EN 60529)
  

Mounting

• Construction: Open REG housing
• Mounting: This surge arrester is intended for fixed mounting on the top-hat rail in distribution boards inside buildings (DIN Rail 35 mm according to EN 50022)
• Ambient temperature: -20°C to +70 °C
• Humidity: < 98% rH (without condensation)
• Mounting: DIN Rail 35 mm (EN50022)
• Material housing: Polyamide
• Colour: Green
• Dimensions: 76 mm x 22.5 mm x 40 mm (l x w x h with housing)
• Weight: 39 g (with housing)