M-system MD74R User manual

EM-8058 Rev.6 P. 1 / 4
INSTRUCTION MANUAL
LIGHTNING SURGE PROTECTOR FOR
RS-485 / RS-422 (ultra-slim) MODEL MD74R
BEFORE USE ....
Thank you for choosing M-System. Before use, please check
contents of the package you received as outlined below.
If you have any problems or questions with the product,
please contact M-System’s Sales Office or representatives.
■PACKAGE INCLUDES:
Surge protector....................................................................(1)
■MODEL NO.
Confirm Model No. marking on the product to be exactly
what you ordered.
■INSTRUCTION MANUAL
This manual describes necessary points of caution when
you use this product, including installation, connection and
basic maintenance procedures.
LIMITATION APPLICABLE TO M-RESTER
The M-RESTER will protect electronics equipment from
damage caused by lightning by absorbing most of the
surge voltages.
However, M-RESTER may not be effective against cer-
tain extremely high voltages caused by a direct or almost
direct hit by lightning.
M-RESTER must be installed according to this installa-
tion / instruction manual.
GENERAL
■FUNCTION & FEATURES
• High discharge current capacity 20 kA (8 / 20 µs), 1 kA
(10 / 350 µs)
• Ultra-thin 7-mm-wide module can be mounted in high
density
• Excellent protection employing multi-stage SPD circuits
• DIN rail mounting and grounding
• Shield terminal provided
■SPECIFICATIONS
See Table 1.
Table 1. Specications
LINE TO LINE LINE TO SG LINE/SG TO EARTH SHLD TO EARTH
Max. continuous operating voltage (Uc) ±5V 5V ±160V ±160V *1
Voltage protection level (Up)
@4kV (1.2 / 50 µs)
±25V 25V ±800V ±800V *1
Leakage current @Uc ≤ 200µA ≤ 200µA ≤ 10µA ≤ 10µA*1
Response time ≤ 4 nsec. ≤ 4 nsec. ≤ 20 nsec. ≤ 20 nsec.*1
Approx. capacitance @ 100 kHz 300 pF 300 pF 100 pF 100 pF
Max. discharge current (Imax) 20kA (8 / 20 µs), 1.0kA (10 / 350 µs)
Nominal current (IN) 100mA
Internal series resistance 2Ω ±10% per line
Input attenuation -0.5 dB max. @DC...2.0 MHz, Z0 = 110Ω
*1. Values for the MD74R-FF. Shortcircuited for the MD74R-FG.
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SENTRONIC AG

MD74R
EM-8058 Rev.6 P. 2 / 4
POINTS OF CAUTION
■ENVIRONMENT
• Indoor use.
• When heavy dust or metal particles are present in the
air, install the unit inside proper housing with sufficient
ventilation.
• Do not install the unit where it is subjected to continuous
vibration. Do not subject the unit to physical impact.
• Environmental temperature must be within -25 to +85°C
(-13 to +185°F) with relative humidity within 30 to 90%
RH in order to ensure adequate life span and operation.
• This unit needs a DIN rail as earth grounding bar. Ox-
ide coating of an aluminium rail may lower the electric
conductivity between this module and the ground. Use a
steel or copper rail.
■DIELECTRIC STRENGTH TESTING
• The surge protector starts discharging when 160V or
greater voltage (with floating shield type) or several volts
(with grounding shield type) is applied between lines and
earth. Remove the grounding wire before conducting a
test. Be sure to return the wire after the test.
■AND ....
• We recommend that you keep spare surge protectors so
that you can replace them when necessary.
• Lightning surge can enter not only through signal lines
but also through power supply lines. We recommend that
you also use the Lightning Surge Protector for Power
Lines for adequate protection.
COMPONENT IDENTIFICATION
Body
Spring Loader
DIN Rail Mounting
Adaptor (for grounding)
Connection
Diagram
(left side)
Model No.
Indication
INSTALLATION
Mount the unit on a DIN rail. Once installed, do not move
it to another DIN rail.
■MOUNTING THE UNIT ON A DIN RAIL
A)Hang the upper hook of the DIN rail mounting adaptor at
the rear side of unit, on the DIN rail.
B)Push in the lower in keeping pressing the unit to the DIN
rail.
C)DIN rails generally have slight individual variability in
size. If you find it difficult to push in the lower part, go
back to (A) and hang the upper part more deeply onto the
rail and try (B) again.
A
DIN Rail
B
■REMOVING THE UNIT
A)Push down the spring loader utilizing a minus screwdriv-
er.
B)Confirm that it is pulled enough down and pull out the
lower part of the unit.
C)Detach the upper part from the DIN rail.
A
B
Spring Loader
C
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SENTRONIC AG

MD74R
EM-8058 Rev.6 P. 3 / 4
TERMINAL CONNECTION
Connect the unit as in the diagram below.
Be sure to ground the DIN rail on which the unit is mounted and cross-wire between the rail and FG terminal of the protected
device as shown in Figure 1 in order to equalize the earth potential.
When the unit is connected with a device which has no FG terminal, ground the surge protector only.
■EXTERNAL DIMENSIONS unit: mm (inch)
8
6
5
4
1
2
3
7
4
1
5
2
6
3
8
7
95 (3.74)
7
(.28)
98 (3.86) [1.5 (.06)]
8–M3 EURO
TERMINAL
DIN RAIL
(35 mm wide)
DIN RAIL
ADAPTOR
WIRE INSERTION ANGLE: approx. 20°
57 (2.24)
1.9 (.07)
■Figure 1. GROUNDING
M-RESTER PROTECTED
EQUIPMENT
FG
CROSSOVER WIRE
Cross-wire from the DIN rail to the metal housing of the protected device
to equalize the ground potential.
Ground only the surge protector when the protected device has no
grounding terminal.
DIN RAIL ADAPTOR
(for grounding)
DIN RAIL
Grounding
■CAUTION WHEN WIRING
Hold the module steady at the front when you
tighten/loosen screw terminals.
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SENTRONIC AG

MD74R
EM-8058 Rev.6 P. 4 / 4
■CONNECTION DIAGRAM
5 2
6 3
7
8
DISCHARGE
ELEMENT
DISCHARGE
ELEMENT
DIN RAIL ADAPTOR
(for grounding)
4 1
52
63
78
41
Series ResistanceSeries Resistance
Protected DeviceMD74R-FF
SG
SHLD
FG
+
–
*2
LINE
DIN RAILDIN RAIL
GroundingGrounding
MD74R-FG*1
Crossover Wire
*5*3*3
*4*4
Crossover Wire
*5
(SHLD)(SHLD)
DISCHARGE
ELEMENT
DISCHARGE
ELEMENT
DIN RAIL ADAPTOR
(for grounding)
Protected Device
SG
SHLD
FG
+
–
LINE
Surge
Side
Surge
Side
Protected
Side
Protected
Side
*1. Choose the MD74R-FG when the shield wire is to be grounded.
*2. When SHLD and SG terminals are not isolated, DO NOT connect the surge protector’s terminal 7 to SHLD.
*3. Oxide film on the surface of an aluminium rail may lower the electric conductivity between this module and the ground.
Use a steel or copper rail.
*4. Be sure to ground the DIN rail. Recommended grounding resistance max. 100 ohms.
*5. Cross-wire from the DIN rail to the metal housing of the protected device to equalize the ground potential.
Ground only the surge protector when the protected device has no grounding terminal.
WIRING INSTRUCTIONS
■EURO TERMINAL
Torque: 0.3 N·m
Applicable wire size: 0.2 – 2.5 mm2
Stripped length: 8 mm
MAINTENANCE
Check surge protectors periodically. Many cases of light-
ning are ignored, and even lightning at a far distance often
causes inductive surges.
We recommend that you check your surge protector about
twice a year, before and after the rainy season. Check
whenever you experience a strong lightning occurrence.
Checking procedure is explained in the following:
■CHECKING
WIRING
1) Make sure that wiring is done as instructed in the con-
nection diagram.
2) Make sure that the DIN rail is connected to the metal
enclosure of protected device.
3) Make sure that the surge protector is securely attached
to the DIN rail, and that the rail is grounded to earth.
DISCHARGE ELEMENT
Preliminary checking can be conducted as following.
For detailed checking, send the surge protector back to M-
System.
1) Remove all wiring connected to the surge protector when
you test the module.
2) Check resistance across the following terminals on the
high resistance range of multimeter (measuring current
≤ 0.25 µA) and confirm no conduction.
Terminals (4) – (5), (4) – (6), (5) – (6),
(6) – (DIN rail), (8) – (DIN rail)
The tester should show 1 MΩ or greater at (4) – (5), (4)
– (6), (5) – (6) and 10 MΩ or more at other terminals.
When measuring across (4) – (6) and (5) – (6), connect the
tester’s probe so that the positive voltage is applied to (4)
and (5) respectively.
For the MD74R-FG, (8) – (DIN rail) should show approx.
0 Ω.
3) Confirm conduction across the same terminals with a 500
V DC 1000 MΩ insulation tester in the same manner as
with the tester. The tester should show 20 MΩ or less.
4) If any of the above tests shows negative, please contact
M-System’s Sales Office or representatives.
056 222 38 18 [e-mail] www.sentronic.com
SENTRONIC AG