Voltage Drop In The Supply; Shielding And Cable Routing - Balluff BML SF2-I2 -A- Z 5-KA Serie Betriebsanleitung

BML SF2-I2 _ _ -A/QZ _ _ - Z _ _ 5-...
Incremental magnetic encoder system
4
Installation and connection (continued)
4.6

Voltage drop in the supply

While operating at 5 V, the operating voltage in
the sensor head must be 5 V ±5%. To
compensate for voltage drops in the supply line,
a sensor head with sense lines
(BML SF2-...-KA/ ...-KD) and a regulated
power supply with sense input (Fig. 4-10) are
recommended.
If this is not possible or desired, integrate the
sense lines of the 12-wire cable (not for 8-wire
cable BML-...-KF...) parallel to the +5-V and
GND lines (Fig. 4-11).
Fig. 4-10: Power supply with sense line
Fig. 4-11: Power supply without sense line
18 english
4.7

Shielding and cable routing

Defined ground!
The linear encoder system and the control
cabinet must be at the same ground potential.
Shielding
To ensure electromagnetic compatibility (EMC), observe
the following:
– The cable shield must be grounded on the controller
side, i.e. connected to the protective earth conductor.
– When ducting the cable between the sensor, controller,
and power supply, it is important to avoid going near
high voltage cables due to interferences.
Stray noise from AC harmonics (e.g. from phase angle
controls or frequency converters) are especially critical
and the cable shield offers very little protection against
this.
Magnetic fields
The position measuring system is a magnetically coded
system.
It is important to maintain adequate distance between the
position measuring system and strong, external magnetic
fields.
Cable routing
Do not route the cable between the position measuring
system, controller and power supply near high voltage
cables (inductive stray noise is possible).
The cable must be routed tension-free.
Bending radius
For information on the permissible bending radius, see
section 7.1.6 on page 23.
Cable length
Cable length max. 20 m. Longer cables may be used if
their construction, shielding and routing prevent noise
interference.
Observe voltage drop in cable!
The nominal voltage on the BML must not be
undercut. Each wire in the cable has a
resistance of 0.2 Ohm/m. When calculating the
drop in voltage, account for the feed and return
lines, i.e. the total resistance is 0.4 Ohm/m.
For the accessory cable resistance, see 8.3 on
page 25.