BCU 440 · Edition 01.17 19
Project planning information
6 Project planning information
6.1 Cable selection
Use mains cable suitable for the type of operation and
complying with local regulations.
Signal and control line: max. 2.5 mm
2
.
Cable for burner ground/PE wire: 4 mm
2
.
Burner ground connector may also be located outdoors.
Do not route BCU cables in the same cable duct as
frequency converter cables or cables emitting strong
fields.
6.1.1 Ionization cable
Use unscreened high-voltage cable, see page 27
(Accessories).
Recommended cable length: max. 50 m.
Lay cable individually and, if possible, not in a metal
conduit.
Install well away from mains cables and interference
from electro-magnetic sources.
Do not lay together with ignition cable.
6
.1.2 Ignition cable
Use unscreened high-voltage cable, see page 27
(Accessories).
Cable length for internal ignition: max. 5 m (16.4 ft).
External electrical interference must be avoided. The
longer the ignition cable, the lower the ignition capacity.
Lay cable individually and, if possible, not in a metal
conduit.
Do not lay UV/ionization cable and ignition cable to-
gether and lay them as far apart as possible.
Screw the ignition cable securely into the ignition trans-
former and feed it out of the unit on the shortest pos-
sible route (no loops) – use the left-hand M20 plastic
cable gland.
Only use radio interference suppressed terminal boots
(with 1 kΩ resistor) for spark electrodes, see page 27
(Accessories).
6.2 Spark electrode
6.2.1 Electrode gap
Gap between electrode and burner ground:
2 mm ± 0.5 mm.
6.2.2 Star electrodes
We recommend using 7.5 kV ignition transformers on
burners with star electrodes.
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