LB-762 Controller Installation Manual
LAB-EL
of joints of analog servomotors (ACTUATOR #N), as there is no connection between these contacts inside the regulator
(galvanic insulation).
24V DC power supply to servomotors has the advantage of permitting longer connecting cables than 24V AC power supply
– see the description below. However, it must be quite well filtered out – the amplitude of pulsations cannot be higher than
10 %.
3.8.2
Connecting cable
MP-BUS bus imposes some restrictions as to the length of cabling and section of wires. While the type of cable has no
greater importance (it does not have to be screened, simplest 3-conductor cable is sufficient), , depending on the type of
power supply (AC/DC), the number of servomotors and the section of the connection cable, different is the maximum
acceptable cable length. Detailed information on the method of setting the maximum connection cable length can be found
in the documentation of Belimo, below presented are the most typical cases for cable with core section 0.75 mm
2
and popular
types of servomotors.
consumed power
power supply 24V AC
power supply 24V DC
20 W/VA
25 m
40 m
40 W/VA
15 m
20 m
60 W/VA
8 m
10 m
Tabela 3.1: Maximum cable length for section 0.75 mm mm
2
One should sum up power collected for all connected servomotors. For example for servomotor LM24A-MP consumed power
is 2.5 W for 24V DC and 5.0 VA for 24V AC. With 8 servomotors we have the sum of powers 20 W for 24V DC and
40 VA for 24V AC, what permits application of cable with length respectively 40 meters at supply 24V DC and 15 meters
at supply 24V AC.
In special cases when larger distances are required, double increase in the cable section up to 1.5 mm
2
permits twofold
growth in these distances.
In the case when each servomotor has its own power supply located in the neighborhood of the servomotor, connection
of MP-BUS bus with LB-762 regulator can be made by two cables. In such case cable length is restricted to 800 meters,
regardless of its section (it is not however recommended to use cable with section smaller than 0.75 mm
2
).
3.8.3
Connections diagram
Connector of LB-762 regulator used for connection of MP-BUS bus is described as
BELIMO PP/MP
and is equipped with 2
contacts:
•
MP
- signal,
•
GND
- ground.
presents the typical manner of connection of MP-BUS bus, using additional common 24V power supply unit.
The manner of laying the cable between LB-762 regulator, the power supply unit and servomotors has no importance here.
It can be running in any convenient way, this may be a layout of bus, star, mixed or any other.
More details concerning MP-BUS bus and its technical parameters can be found in BELIMO documentation.
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