2
INM F300 rev 6
DRAFT - 09 July 2019
Short-circuit protection
To minimize susceptibility to single points of failure, F300 Megablocks are provided
with built-in SpurGuard™ short-circuit protectors, which prevent the entire Fieldbus
segment from being pulled down in the event of a short circuit on any one of the
individual field devices or spur cable runs.
NOTE
During a short circuit, the shorted spur draws more current than a normal
Fieldbus device - this must be taken into account in segment design.
Diagnostic aids
Each Megablock comes with a green LED to indicate whether DC Power is present,
and a red LED next to each numbered spur indicates when the spur is in short circuit.
3
COMPONENTS AND ACCESSORIES
Product part numbers and their descriptions are listed below.
Part Number
Description
F304[-PC]*
4-way Megablock
F308[-PC]*
8-way Megablock
F312[-PC]*
12-way Megablock
F97
Terminator for F300 range of Megablocks
F300-A01-5
Trunk-spur partition – pack of 5
FS32
Spur surge protector module
F300-BAR-5
FS32 grounding bars for trunk - pack of 5
F304-BAR-10
FS32 grounding bars for F304 - pack of 10
†
F308-BAR-10
FS32 grounding bars for F308 - pack of 10
†
F312-BAR-10
FS32 grounding bars for F312 - pack of 10
†
* The standard connector for the Megablock is a pluggable screw terminal (elevator type).
Pluggable spring-clamp connectors rely on constant spring pressure to maintain contact with the
wire. To order Megablocks with pluggable spring-clamp connectors, add a –PC suffix to the part
number (i.e. F304-PC).
† Up to two bars may be required for each Megablock.
4
MECHANICAL
4 .1 Mounting orientation
Megablocks mount vertically or horizontally on 35mm DIN rail within a field junction
box The use of DIN rail end stops are recommended to prevent sliding (especially for
vertical installations).
Eight, and twelve port Megablocks have areas on their body for labelling so that
segments can be easily identified according to plant standards.
4 .2 Enclosure requirements
4 .2 .1 General requirements
Megablocks may be mounted in hazardous (classified) areas – see section 8. The
following conditions must also be satisfied to ensure safe and reliable operation.
a) Prevent any form of pollution that could compromise the operation of the unit.
For example, choose an unpolluted location or a suitable enclosure to protect the
assembly.
b) Provide an adequate level of mechanical protection. This can be achieved by
selecting a protected location, a suitable enclosure, or a combination of both.
c) Ensure that all cable entries and connections are secure by making provision for
