Labko MD-1 D30646Ae
Installation Instructions
Copyright © 2010 Labkotec Oy 4/5 We reserve the right for changes without notice
3.2 CONNECTIONS
Figure 3. Electrical connections
X1:
L1 = mains supply phase line conductor
N = mains supply neutral conductor
X2-X3: (CURRENT LOOP)
C1(+) = (+) pole of the current loop
C2(-) = (-) pole of the current loop
SHIELD1 = shield for a cable pair
SHIELD2 = common cable shield
X4-X5-X6: (RS-232)
SHIELD22 = cable shield
SHIELD12 = for equipotential grounding
RTS = handshake signal
RxD = receive signal
TxD = transmit signal
0V = RS-232 signal ground
3.3 TO BE NOTICED DURING
INSTALLATION
The device does not have a mains switch:
A mains switch (250 VAC / 1 A), which isolates
both mains conductors (L1, N), must be
installed near MD-1 unit for service and repair
purposes.
In installations, where digital current loops of
multiple LPS-1 units are connected in series,
all units (max. 9 units/switch) can be fed
through the same switch.
Labelling must be provided immediately
adjacent to the switch to permit rapid
identification of the circuit or group of circuits
thereby controlled.
3.4 CABLING
3.4.1 CABLING BETWEEN LPS-1 POWER
SUPPLY AND MD-1
Shielded instrument cable with two conductors
with minimum of 0,5 mm2 cross sectional area, is
suitable for carrying the digital current loop
between the LPS-1 power supply and MD-1.
The maximum length of the current loop is 400 m
when using the type of cable mentioned above.
The current loop conductors of the cable are
connected to CURRENT LOOP terminals C1 (+)
and C2 (-).
In order to achieve the best possible protection for
electromagnetic interference, it is recommended
to use a cable, which has a common shield for the
whole cable in addition to the shield for the cable
pair, see attached drawing D30611. In this case
one must notice that different shield types must be
electrically separated from each other.
The shield for a cable pair is connected to
SHIELD1 and the common shield to SHIELD2. In
case there is only one shield, connect it to
SHIELD2.
Please check also the LPS-1 Installation and
Operating Instructions.
3.4.2 RS-232 CONNECTION
The maximum length of a RS-232 cable according
to RS-232 standard is 16 m with a baud rate of
19,2 kbaud (maximum cable capacitance 2200
pF). In practice the cable can be somewhat longer
due to baud rate of 300 baud when
communicating with Labko 3000 probes.
In case the RS-232 cable shield is not grounded
in the D-connector end (e.g. at the PC), the shield
can be grounded e.g. by connecting the MD-1
conductor SHIELD12 to grounding or true earth.
4. SERVICE AND REPAIR
The mains fuse (marked 80 mAT) can be replaced
with another 5 x 20 mm / 80 mAT glass tube fuse
complying with EN 60127-2/3.
