SD Series

Ultra-slim user-friendly devices for protectiing electronic

equipment and systems against surges on signal and I/O
cabling

O Range of ATEX Certied intrinsically safe surge

protectors

O Ultra-slim space-saving design; easy installation

O Multistage hybrid protection circuitry -- 20kA

maximum surge current

O Range of voltage ratings -- to suit all process

I/O applications

O High bandwidth, low resistance, RTD, PSTN and

3-wire transmitter versions available

O 10 year product warranty

The SD Series is a range of surge pro- is provided by the SD07, SD16, SD32 and One simple manual operation clamps
tection devices combining unparalleled SD55 units. In addition, a third connection modules securely onto DIN rail, which au-
packing densities, application versatility, on the eld and safe side of the protector tomatically provides the essential high-in-
proven reliable hybrid circuitry, simple in- is provided in order to terminate screens tegrity earth connection.
stallation and optional loop disconnect safely.
facilities features which make the series Top-hat (T-section) DIN rail is gener-
the ultimate surge protection solution for For three wire applications the specially ally suitable for mounting SD modules al-
process equipment, I/O systems and com- designed SDRTD (Resistance Tempera- though for adverse environments, a spe-
munications networks. ture Detector) and the SD32T3, (for sepa- cially-plated version is available from MTL
rately powered 4-20mA loops) provide full Surge Technologies. A comprehensive
The exceptionally high packing densi- 3-wire protection in a single compact unit. range of mounting and earthing accesso-
ties are the consequence of an ultra slim The recommended choice for the protec- ries can also be supplied, see page 7 for
footprint for individual modules which can tion of 3-wire pressure transducers on further details.
thus double-up as feedback terminals. low power circuits is the SD07R3.
Each module provides full hybrid surge pro-
tection for 2 and 3 wire loop protection. For higher bandwidth applications, the
SDR series has been developed to meet
Modules with a comprehensive range of the demands of todays highest speed
voltage ratings cover all process related communication systems.
signals such as RTDs, THCs, 4 to 20mA
loops, telemetry outstations, shut-down 120V and 240V AC versions are avail-
systems and re and gas detectors. able for I/O and power supplies up to
three Amps of load current.
Optional loop disconnect, is a feature
which allows commissioning and mainte- Telephone networks
nance to be carried out without removal can be protected by
of the surge protection device. This facility the SDPSTN.

Data & Signal

Protection
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 Guide to applications and selection
The SD Series of SPDs includes models for almost all possible applications operating at voltages up to 250V ac. The optional fuse/
disconnect package provides both fused protection against fault currents and a convenient method of isolating eld circuitry from
protected circuitry without needing additional disconnect terminals. The standard fuse (which is replaceable) is rated 250mA with
50mA fuses also being available by special request. Where only the disconnect feature is required, solid links can be used.

As an example, this feature is of particular value in applications in which an SPD is used with a bulk power supply feeding multiple loops.
The individual module fuse prevents a fault or follow on current on one loop disrupting the power supply to the others. Also, loops can
be removed from the circuit for maintenance reasons or added without needing additional disconnect terminals.

The following guide to selection suggests the most suitable SDs for a number of specic applications. For technical information, see
the detailed specications on the back page of this publication (some eld circuit protection is shown for completeness).

FIELD CIRCUIT PROTECTED CIRCUIT

Analogue inputs
(high-level)
2-wire transmitters, 4-20mA,
conventional and smart
The SPDs recommended for use with conven-
tional and smart 4-20mA transmitters (fed by
a well-regulated supply) are the SD32 and SD55,
the choice depending upon the maximum work-
ing voltage of the system (32V and 55V respec-
tively). The diagram illustrates a prime example
of an application for which the fuse/disconnect 2-wire transmitters
facility is particularly useful, however, both models
are available in X versions without the optional
fuse/disconnect feature.

Analogue inputs
(low-level)
RTDs
These applications are best served using the
SDRTD. For optimum accuracy, the energising
current should be chosen to ensure the voltage
across the RTD does not exceed 1V over the
full measurement range. When using a PT100
device, we recommend an energising current of
1mA.
3-wire RTDs

photocells, THCs, mV sources and turbine

owmeters
The SD07 or SD16 (depending upon the opera-
tional voltage) are the favoured choices for this
application. SD07X and SD16X are also suit-
able.

photocells, THCs, mV
sources and turbine
owmeters

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 FIELD CIRCUIT PROTECTED CIRCUIT

Analogue outputs
Controller outputs (I/P converters)
For this application, the recommendations are
the SD16, SD32 and SD55 (and the equivalent
X versions), the nal choice depending upon the
operating voltage.

Controller outputs
(I/P converters)

Digital (on/off) inputs

Switches
Suitable SPDs for switches include the SD07,
SD16, SD32 and SD55 modules the choice
depending upon the operating voltage of the sys-
tem. The X versions of these are also suitable.

Switches

Digital (on/off) outputs

Alarms, LEDs, solenoid valves, etc
The recommended choice for this application is
the SD32 or SD32X.

Alarms, LEDs, solenoid

values, etc.

Telemetry (PSTN)
Telemetry outstations
The SDPSTN has been designed specically for
the protection of signals transmitted on public
switched telephone networks.

Telecom line

AC supplied equipment
PLC, I/O systems
For systems on 110-120V ac, the SD150X is the
recommended choice and for 220-240V ac sys-
tems, the SD275X is recommended.

PLC, I/O systems

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 Transmitter and sensor protection
Transmitters and sensors are widely used in highly exposed areas and where lightning damage is common. In many cases,
the ideal solution for 2-wire transmitters or sensors is the TP48 which mounts directly onto the transmitter housing via
spare cable entries. Where these entries are not available or 3-wire devices are used, the compact design and simple instal-
lation of the SD series makes it the obvious choice for transmitter protection.

The SDs within the junction box should be installed no further than one metre away but as close as possible to the sensor or
transmitter they are protecting. A bond is required from the general mass of steelwork to the sensor or transmitter housing
either using a at short braid or a cable of at least 4mm2 cross sectional area. In most instances this bond is automatically
made by xing the metallic transmitter housing to the plant structure. This bond ensures the voltage difference between the
signal conductors and the transmitter housing is below the transmitters insulation rating. Please note that the transmitters
or sensors are connected to the Protected Equipment terminals of the SD and not the Field Cables.

SD PROTECTED FIELD CIRCUIT TO HOST CIRCUIT

2-wire transmitters or
sensors
4-20mA transmitters, conventional and
smart
Where the TP48 is not an acceptable solu-
tion, either because of technical suitability or
difculties in mounting, the SD16X, SD32X
and SD55X are an excellent alternative.

3-wire transmitters or 2-wire transmitter or sensor

sensors
Vibration Sensors and 4-20mA loop pro-
cess control systems invariably require
three wire connections, when powered
from an external source.

This may be accomplished in one unit by us-

ing the SD32T3 three terminal Surge Pro-
tection Device (SPD).

Because the SD32T3 protects all three

conductors within the same unit, higher
protection is achieved, as the SPD hybrid
circuitry is common to all three wires.

The SD07R3 is available for the protection

3-wire transmitter or sensor
of 3-wire pressure transducers on low pow-
er circuits.

4-wire transmitters or
sensors
Flow meters, level detectors, etc.
4-wire systems such as level detectors re-
quire two SDs, one for the supply and the
other for the transmitter output. Generally
the voltages across the pairs are similar
and so the recommended choice would be a
pair of SD16X, SD32X or SD55Xs. However,
mains powered transmitters should be pro-
tected with an SD150X or 275X (depending
upon supply voltage) for the supply inputs.

Loadcells are catered for by MTL Surge

Technologies LC30 which is suitable for
both 4 and 6-wire load cells.
4-wire transmitter or sensor

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 Communication systems protection
High speed data links between buildings or one part of a plant to another have become more common with the widespread
use of smart transmitters and the increase in unmanned installations. The SD series has an SPD suitable for all process I/O
applications with a choice of low resistance units, high bandwidth and a variety of voltage variants. The SDR series has been
specially designed to meet the requirements for high speed data links with an extremely high bandwidth.

TP PROTECTED SD PROTECTED HOST CIRCUIT

FIELD CIRCUIT

Communication systems
RS232, RS422, RS485
The recommended choice for these appli-
cations is the SD16R or SD32R depending
on the maximum driver signal.

RS232, RS422, RS485

PROTECTED FIELD CIRCUIT SD PROTECTED HOST CIRCUIT

Bus powered systems
There are a variety of bus powered systems
specially designed for the process industry.
The ideal surge protection device for these
systems is the SD32R as it has a very high
bandwidth and a modest in-line resistance.

Bus powered systems

Table 1
Application Preferred SPD Alternative
Typical Applications
Table 1 shows suitable SD devices for dif-
Allen Bradley Data Highway Plus SD16R
ferent applications. In some applications al-
Foundation Fieldbus
ternative devices may be used, for example,
31.25kbits/s voltage mode SD32R
where lower in-line resistance or a higher
1.0/2.5 Mbits/s SD55R
voltage power supply is used.
HART SD32X SD32, SD32R
Honeywell DE SD32X SD32, SD32R
MTL Surge Technologies has operationally
LonWorks
tested the recommended SD series with
FFT-10 SD32R
representative highways listed but no for-
LPT-10 SD55R
mal approval for their use in systems by the
TP-78 SD07R
respective bodies has been sought.
IS78 SD32R
Modbus & Modbus Plus (RS485) SD16R
PROFIBUS
DP SD32R
PA (IEC 1158, 31.25 kbits/s) SD32R
RS232 SD16 SD16X
RS422 SD07R
RS423 SD07R
RS485 SD07R
WorldRP (IEC 1158) SD32R
31.25 kbits/s voltage mode
1.0/2.5 Mbits/s SD55R

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 Hazardous area applications
ZoneO/Zone1
The dangers from lightning induced spark- The power rating for each of these is dependent on the table shown below.
ing in Zone 0 are considered real enough to Pi = 1W (30C to +75C)
require preventative measures. IEC 60079- Pi = 1.2W (30C to +60C)
14 (1996-12) Electrical apparatus for explo- Pi = 1.3W (30C to +40C)
sive gas atmospheres Part 14: Electrical The SD** Series are classied as simple apparatus and are intended for use in Zone 2 or
installations in hazardous areas (other than safe areas only, because their fuses are not fully encapsulated.
mines) stresses the importance of SPDs in
hazardous areas. An outdoor installation
where there is a high likelihood of both light-
ning induced transients and combustible Installation
gases requires the installation of SPDs to Positioning
prevent possible ignition of the gases. Areas
seen particularly at risk include ammable The SDs should be mounted on the eld wiring side to ensure that any surges entering
liquid storage tanks, efuent treatment from the eld do not damage any intrinsically safe barriers or galvanic isolators in the
plants, distillation columns in petrochemical system. The SDs and IS interfaces should be mounted close to each other but on sepa-
works and gas pipelines. rate DIN rails in order to maintain the required 50mm clearance between safe area and
hazardous area terminals.
SPDs for transmitter protection should be
installed in Zone 1 but sufciently close to
the Zone 0 boundary to prevent high volt-
ages entering Zone 0. The distance from
the SPD to Zone 0 should be less than one
metre where possible. However, in practice
the SPD would normally be mounted on the
transmitter or sensor housing which usu-
ally lies in Zone 1 and is very close to Zone
0. Because there is only a very small free
volume, the SD Series is suitable for mount-
ing in ameproof or explosion proof enclo-
sures.

Zone 2
The SD series is suitable for protecting
electrical circuits in Division 2, Zone 2 and
can be used without affecting the safety as-
pects of the circuit. Non-incendive (low-cur-
rent) circuits can be protected using any
SD series unit mounted in either the safe
or hazardous area including those with the Earthing
fuse disconnect facility. Non arcing (high
The recommended earthing for eld mounted devices has been illustrated previously but
current) circuits can also be protected ex-
it is the earthing at the control panel that is more critical as there are usually a number of
cept that SPDs with the fuse disconnect fa-
earthing systems, each with their own requirements. The earthing system illustrated here
cility may only be mounted in the safe area.
replaces the instrument 0V bond, the control system PSU bond and the IS earth with one
For use in these circuits the units must be
single earth connection to meet all the design requirements and give the most effective
mounted in a suitable enclosure, normally
protection against the effects of lightning induced surges.
the minimum requirements are IP54 and
7Nm resistance to impact. The SD series is
self certied by MTL Surge Technologies as
being suitable for this purpose.

Certication
Introducing surge protection into Intrinsi-
cally Safe (IS) circuits is trouble free as long
as the current and power parameters are
not exceeded. In the SD Series, the SD**X,
SD**R, SD**R3, SDRTD and SD**T3 all
have ATEX certication for use in IS circuits
located in Zones 0, 1 or 2. The certication
parameters for the SD**X and SD**T3
are:
EEx ia IIC T4, Li = 0.22mH
Ii = 260mA for Ui up to 20V
Ii = 175mA for Ui up to 26V
Ii = 140mA for Ui up to 28V
Ii = 65mA for Ui up to 60V
The certication parameters for the SD**R,
SD**R3 and SDRTD are:
EEx ia IIC T4, Li = 0
Ii = 260mA for Ui up to 60V
6
 SD Series mounting kits and accessories
The SD Series has a full range of mounting kits and accessories to simplify installation and tagging of individual loops. Insulat-
ing spacers (ISP7000) are available to allow mounting of the units onto backplanes without compromising correct earthing
practice. These are placed at regular intervals along the rail or at each end as required. Earth connections can be made to
the DIN rail via the earth terminal (ETL7000). Weatherproof enclosures are also available with all the necessary mounting
accessories to install the SD series surge protection devices.

Two tagging systems are available. One consists of tagging strips (TAG57) with labels (TGL57) mounted on posts (IMB57) at
each end of a row of surge protection devices (SPDs). The other consists of separate tagging identiers (BRI7000) mounted
on the tops of individual SPDs. Both methods can be used conjointly. Replaceable fuses or solid links are available in packs of
5 (SD-F25, SD-F05 and SD-LNK).

Mounting accessories
ISP7000 Insulating spacer DIMENSIONS
THR2 Standard DIN rail, 35mm x 7.5mm
THR7000 T-section DIN rail, specially nickel plated,
35mm x 7.5mm, 1m length
Earthing/earth rail accessories
ETL7000 Earth terminal, DIN rail mounted
IMB57 Insulated mounting block (two needed)
ERB57S Earth rail bracket, straight
ERB57O Earth rail bracket, offset
ERL7 Earth rail, 1m length
ETM7 Earth terminal, pack of 50
Tagging accessories
TAG57 Tagging strip, 1m length
TGL57 Tagging strip labels, set of 10 x 0.5m
BRI7000 Barrier identier
BIL7000 Barrier identication labels, sheet of 120
BIL7000L Barrier identication labels, A4 sheet of 126
Enclosures
DX070 Enclosure for up to 9 x SD series SPDs
DX170 Enclosure for up to 22 x SD series SPDs
DX430 Enclosure for up to 58 x SD series SPDs
Accessories (replacement)
SD-F25 Replaceable fuse pack - 250mA standard
(available in packs of 5)
SD-F05 Replaceable fuse pack - 50mA special
(available in packs of 5)
SD-LNK Solid Link (available in packs of 5)

SIL information
Failure rates according to IEC 61508

SD SU* DD DU
SD07, SD16, SD32, SD55 0 FIT 75 FIT 15 FIT 2 FIT
SD07R, SD16R, SD32R, SD55R 0 FIT 46 FIT 15 FIT 2 FIT
SD07X, SD16X, SD32X, SD55X 0 FIT 47 FIT 15 FIT 2 FIT
SD07R3, SD07T3, SD07X3 0 FIT 73 FIT 20 FIT 7 FIT
SD16R3, SD16T3, SD16X3, SD32R3, SD32T3,
0 FIT 72 FIT 18 FIT 6 FIT
SD32X3, SD55R3, SD55T3, SD55X3
SDRTD 0 FIT 71 FIT 20 FIT 9 FIT

The user of the SD Series can utilize these failure rates in a probabilistic model of a safety instrumented function (SIF) to determine the
suitability in part for safety instrumented system (SIS) usage in a particular safety integrity level. A full table of failure rates in presented
in the EXIDA report (section 4.4) along with all assumptions.

*The Residual Effect failures are included in the Safe Undetected failure category according to IEC 61508. Note that these failures
alone will not affect system reliability or safety and should therefore not be included in spurious trip calculations.

Safe Failure Fraction needs to be calculated on (sub)system level.

A complete copy of the EXIDA report can be downloaded at www.mtlsurge.com.

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Specification Model Nominal Nominal Series Max. Rated Voltage Residual Bandwidth Special
All gures typical at 25C (77F) unless otherwise stated voltage+ current resistance leakage voltage Protection voltage (Frequency) feature
(Un) (IN) current (MCOV) level (Up)
Protection @1kV/s @isn
Full hybrid line to line (Vdc) (Vac) (mA) (/line) (A) (Uc) (V) (V) (fG)
Each line to screen/ground
Max. discharge surge current (Imax) (8/20s) SD07 7 5 250 4.2 500 7.7 <12 30 25kHz Fuse Disconnect
20kA (8/20s) SD16 16 11 250 4.2 5 17 <25 40 25kHz Fuse Disconnect
6.5kA (SD150X and SD275X only) SD32 32 22 250 4.2 5 36 <45 60 25kHz Fuse Disconnect
Nominal discharge surge current (isn) SD55 55 38 250 4.2 5 62 <90 100 25kHz Fuse Disconnect
3kA (8/20s)
Lightning impulse current (Iimp) (10/350s) SD07R 7 5 400 2.7 500 7.7 <12 30 50MHz High Bandwidth
2.8kA SD16R 16 11 400 4.7 5 17 <25 40 50MHz High Bandwidth
1.0kA (SD150X and SD275X only) SD32R 32 22 400 10 5 36 <45 60 50MHz High Bandwidth
Response time SD55R 55 38 400 10 5 62 <90 100 50MHz High Bandwidth
<1ns
RTD resistance range (SDRTD) SD07X 7 5 400 2.2 500 7.7 <12 30 25kHz Low Resistance
10 to 1500 SD16X 16 11 400 2.2 5 17 <25 40 25kHz Low Resistance
Degradation accuracy (SDRTD at 1mA) SD32X 32 22 400 2.2 5 36 <45 60 25kHz Low Resistance
0.1% (RTD resistance > 100) SD55X 55 38 400 2.2 5 62 <90 100 25kHz Low Resistance
0.1 (RTD resistance < 100)
Ambient temperature SD32T3 32 22 400 2.2^ 5 36 <45 75 720kHz 3 Terminal
40C to +80C - working (-40F to 176F) 10**
40C to +80C - storage (-40F to 176F) SD07R3 7 5 400 2.7 500 7.7 <12 30 50MHz 3 Terminal
Humidity SD16R3 16 11 400 4.7 5 17 <25 40 50MHz 3 Terminal
5 to 95% RH (non-condensing) SD32R3 32 22 400 10 5 36 <45 60 50MHz 3 Terminal
Category tested SD55R3 55 38 400 10 5 62 <90 100 50MHz 3 Terminal
A2, B2, C1, C2, C3
Overstressed fault mode in=3kA SDRTD 1 0.75 10< 2.7 0.3 5 <12 38 50MHz 3-wire RTD
12kA
9kA (SD150X and SD275X only) SDPSTN 162 114 550 4.7 5 175 <200 235 4MHz PSTN
Impulse durability (8/20s)
ac
10kA ac rms dc rms
6.5kA (SD150X and SD275X only) SD150X 170 120 3A 0.1 250 170 130 <400 450 - High current
Terminals SD275X 339 240 3A 0.1 250 350 275 <700 850 - High current
2.5mm2 (12 AWG)
Mounting Note: all gures are typical at +25C unless otherwise stated; *standard fuse; +over full working temperature range;
T-section DIN-rail 35 x 7.5 or 35 x 15mm rail at 20mA with a 250mA standard fuse; these units need external 3A fuses; ^Signal; **Power & Common; <maximum
(1.38 x 0.3 x 0.6) energizing current depends upon RTD resistance. See page 2 for details.
Weight
70g approximately (2.5oz) Blue color signies products ATEX certied EEx ia IIC T4.
Case ammability
Denitions of terminology used in table 4 Voltage protection level (Up)
UL94 V-2
1 Working voltage (Un) Peak output voltage after injection of test impulse
AC durability
Maximum voltage between lines or lines/ground for the from 1kV/s generator (often known as let-through
1Arms, 5T
specied leakage current voltage)
Service conditions
2 Maximum leakage current (Ic) 5 Bandwidth
80kPa - 160kPa
Maximum current drawn by the SPD at the working Frequency range up to which ac signals can be
5% - 95% RH
voltage transmitted without undue attenuation; 3dB into
EMC compliance
3 Maximum continuous operating voltage (Uc) 50 (600 for the SDPSTN)
To Generic Immunity Standards,
Maximum voltage that can be applied to the protected
EN 50082, part 2 for industrial
terminals without damage
environments
R&TTE compliance
EN 50082-2 : 1995
Approvals
EN 41003 : 1999 Country Standard Certicate/ Approved for Product
EN 60950 : 1992 (Authority) File No.
(not applicable to SD150X and SD275X)
LVD compliance BASEEFA EN 50014:1997 BASEEFA EEx ia IIC T4* SD07X,SD16X,SD32X,
SD150X & SD275X (EC) EN 50020:2002 02ATEX0211X SD55X,SD07R, SD16R,
EN 60950 : 1992 EN 50284:1999 SD32R,SD55R,SDRTD,
EN 61010 : 1995 SD32T3,SD07R3,SD16R3,
SDPSTN SD32R3,SD55R3
EN 41003 : 1999 CSA/C/US CSA C22.2 No. 0-M1991 LR 103652-3 EEx ia Class 1, SD07,SD16,SD32,SD55,
IEC compliance (Canada, USA) CSA C22.2 No. 157-M1992 Groups A, B SD07X,SD16X,SD32X,
EN 61643-21:2001 UL 913, 5th edition C and D, T4 SD55X,SD07R,SD16R,
ANSI/IEEE testing CSA C22.2 No. 142-M1987 Class 1, Div 2 SD32R,SD55R,SDRDT,
C62.41-1-2002 CSA C22.2 No. 213-M1987 Groups A,B,C, D T4 SD32T3,SD07R3,SD16R3,
C62.41-2-2002 UL 508, 17th edition SD32R3,SD55R3
C62.45-2002 UL 1604, 3rd edition
UL UL 497B Listed E220693 Isolated loop SD07,SD16,SD32,SD55
(USA) communication SD07X,SD16X,SD32X
To order specify - circuits SD55X,SD07R,SD16R
Order by module, as listed in the specication table SD32R,SD55R,SD07R3
and/or accessory part numbers as dened on SD16R3,SD32R3,SD55R3
page 7. SD32T3,SD55T3,
SD07X3,SD16X3,SD32X3,
Note: In accordance with our policy of continuous improvement,
SD55X3,SDRTD
we reserve the right to change the products specication without UL UL 1449 E217523 AC power SD150X,SD275X
notice. (USA, Canada) Recognised Component protection
Austel AS/NZ3548:1995 __ Private Wire SD07R
For more information please contact your local MTL (Australia) AS/NZS4117:1996
sales ofce: TS001: 1997

* See page 6 for further details

901-107 Rev O 06/29/09

The Americas: +1 800 835 7075

UK: +44 (0)1582 723633
Singapore: +65 6 487 7887
The Netherlands: +31 (0)481 450250
Italy: +39 (0)2 6180 2011
Australia: +61 (0)8 9455 2994
India: +91 (0)44 450 1660

Local sales ofce information is also available on our web site at:
www.mtlsurge.com/support/distribution/index.htm