M-system MD7LC, Instruction Manual

Page: 4 / 4

MD7LC
EM-8063 Rev.3 P. 4 / 4
■
CONNECTION DIAGRAM
Strain Gauge
Transmitter
(protected device)
G
Strain Gauge
Shield Wire
EXC.
OUTPUT
M-RESTER
surge
side
surge
side
protected
side
protected
side
MD7G
OUTPUT
POWER
EXC.
INPUT
–
+
U
–
+
–
+
G
V
DIN RAIL ADAPTOR
(for grounding)
DIN RAIL
Grounding
DIN RAIL ADAPTOR
(for grounding)
7 8
MD7G
DIN RAIL ADAPTOR
(for grounding)
8 7
5 2
6 3
7 8
4 1
M-RESTER
DIN RAIL ADAPTOR
(for grounding)
2 5
3 6
8 7
1 4
* 1. Without the MD7G, cross-wire between the DIN rail and the metal housing of the protected device to equalize the earth potential.
*
2. 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.
* 3. Be sure to ground the DIN rail. Recommended grounding resistance ≤100
Ω.
* 2
* 3
DIN RAIL
Grounding
* 2
* 3
*
1
*
1
WIRING INSTRUCTIONS
■
EURO TERMINAL
Torque: 0.3 N·m
Applicable wire size: 0.2 – 2.5 mm
2
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
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), (6) – (8),
(5) – (DIN rail), (8) – (DIN rail)
The tester should show 1 MΩ or greater for the terminals
(6) – (8), 10 MΩ or greater for other sets of terminals.
When measuring across (4) – (5), connect the tester’s
probe so that the positive voltage is applied to (4).
3) Confirm conduction across the same terminals with a 500
V DC 1000 MΩ insulation tester The tester should show
20 MΩ or less.
4) If any of the above tests shows negative, replace the
surge protector.
056 222 38 18 mailbox@sentronic.com www.sentronic.com
SENTRONIC
AG