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EM-8061  Rev.4  P. 1 / 4

INSTRUCTION MANUAL

LIGHTNING SURGE PROTECTOR FOR

THREE-WIRE SIGNAL LOOP

 (ultra-slim)

MODEL

MD73W

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.
When using this product in potentially explosive atmos-
phere or hazardous (classified) location, you have to follow
the safety procedure to install it.  Please refer to “SAFE IN-
STALLATION MANUAL” for each type of certification.

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

 

SPECIFICATIONS

LINE TO LINE 

LINE TO EARTH

Max. continuous
operating voltage (Uc)

±32V

±32V

Voltage protection level
(Up) @6kV (1.2 / 50 µs)

±60V

±60V

Leakage current @Uc

≤5µA

≤5µA

Response time

≤4 nsec.

≤20 nsec.

Max. discharge current 
(Imax)

20kA (8 / 20 µs)

1.0kA (10 / 350 µs)

Nominal current (I

N

)

400mA

Internal series resistance

≤2.2Ω ±20% per line

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 ±32V or
greater voltage is applied between lines and earth.  Re-
move 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

056 222 38 18

mailbox@sentronic.com

www.sentronic.com

SENTRONIC

AG

Summary of Contents for MD73W

Page 1: ...ECIFICATIONS LINE TO LINE LINE TO EARTH Max continuous operating voltage Uc 32V 32V Voltage protection level Up 6kV 1 2 50 µs 60V 60V Leakage current Uc 5µA 5µA Response time 4 nsec 20 nsec Max discharge current Imax 20kA 8 20 µs 1 0kA 10 350 µs Nominal current IN 400mA Internal series resistance 2 2Ω 20 per line POINTS OF CAUTION ENVIRONMENT Indoor use When heavy dust or metal particles are prese...

Page 2: ... 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 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 t...

Page 3: ...g DIN RAIL DIN RAIL ADAPTOR for grounding DIN RAIL Grounding DISCHARGE ELEMENT Receiver FG Transmitter FG 1 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 2 Be sure to ground the DIN rail Recommended grounding resistance 100Ω 3 Cross wire between the DIN rail and the metal housing of the protected dev...

Page 4: ... 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 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 and confirm no con duction Terminals 4 5 4 6 5 6 4 DIN...

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