MDP-DM3
5-2-55, Minamitsumori, Nishinari-ku, Osaka 557-0063 JAPAN
Phone: +81(6)6659-8201 Fax: +81(6)6659-8510 E-mail: [email protected]
EM-8110 Rev.9 P. 3 / 3
TERMINAL CONNECTION
Connect the unit as in the diagram below.
Be sure to cross-wire between the Ground terminal (G) and that of the protected equipment. When the surge protector is con-
nected with a device which has no ground terminal such like M-System’s (See figure below), ground the M-RESTER Ground
terminal (G) only.
(Protected Device)
(Protected Device)
C
B
3
2
MDP-DM3
G
A
1
3
2
MDP-DM3
Shielded Twisted-pair Cable
RS-422/485
Communication Line
G
C
B
A
1
FG
+
–
SHLD
FG
+
–
SHLD
Grounding
≤100
Ω
Grounding
≤100
Ω
*
1
*
1
*
2
*
2
*
3
*
3
*
4
*
4
*
1. Applicable devices: M-System’s MsysNet or SIN-NET devices which employ RS-422/485 communication standards.
*
2. Recommended cable length between the surge protector and the protected device: 1 meter at the maximum
*
3. No connection is required if the protected device has no shield terminal.
*
4. Cross wire between the protected device’s FG terminal and the surge protector’s G terminal, and ground to the earth
at the surge protector side.
Ground only the surge protector if the protected device has no FG terminal.
■
GROUNDING
M-RESTER
PROTECTED
EQUIPMENT
G
G
CROSSOVER WIRE
GROUNDING
(100 ohms or less)
A crossover wire between M-RESTER ground and the ground or
metallic housing of the equipment is required for protection.
If the protected equipment has no ground terminal, ground the
M-RESTER only.
When the M-RESTER is mounted with DIN Rail Mounting Adapter,
connect the grounding wire to the mounting screw of the M-RESTER.
WIRING INSTRUCTIONS
■
SCREW TERMINAL
Torque: 0.8 N·m
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 Ground terminal (G) is connected to
the metallic housing of protected equipment.
3) Make sure that the Ground terminal (G) is grounded to
earth.
DISCHARGE FUNCTION
The M-RESTER Tester is available for a preliminary check-
ing of the surge protector’s head element. For detailed
checking, send the surge protector back to M-System.
It is not applicable to the products manufactured earlier
than Year 2004 (identified by 8-digit serial No. starting with
H through M, or 4-digit serial No.).
Approximate testing procedure without using the Tester is
explained as below.
1) Remove all wiring connected to the surge protector when
you test the element module.
2) Check resistance across the following terminals on the
high resistance range of multimeter (measuring current
≤ 0.25µA) and confirm no conduction. The meter shows ≥
10MΩ at (A) – (G), ≥1MΩ at other terminals. When meas-
uring across (A) – (B) and (A) – (C), connect the probes so
that positive voltage is applied to (B) and (C) respectively.
Terminals (A) – (B), (A) – (C), (B) – (C)
(A) – (G), (B) – (G), (C) – (G)
3) Confirm conduction across the same terminals with a
500V DC 1000MΩ insulation tester (The tester shows ≤
20MΩ).
If any of the above tests shows negative, please contact
M-System’s Sales Office or representatives.
