Electrical installation 47
Connecting the cables to the I/O terminals
Connect the conductors to the appropriate terminals of the I/O section (refer to Default I/O
connection diagram on page 46). At the terminal block, use shrink tubing or insulating tape
to contain any stray strands. Especially for multiple shields, you can also terminate the
shield with a lug and fasten it with a screw to the nearest grounding clamp. Leave the other
end of the shield unconnected or ground it indirectly through a high-frequency capacitor,
for example, 3.3 nF/630 V. You can also ground the shield directly at both ends, if they are
in the same ground line with no significant voltage drop between the end points. Tighten
the screws to secure the connection.
Note: Keep signal wire pairs twisted as close to the terminals as possible. Twisting the
wire with its return wire reduces disturbances caused by inductive coupling.
Fast power off circuit
The FPO circuit is powered from the 24 V DC circuit which is connected directly to the Fast
Power Off switch (S20). The Fast Power Off switch is a locking type (twist release) push
button equipped with two N.C. contacts.
The N.C. contact connects to the main contactor enable relays (-K11) through the relay
output of the main control board. All of the contactor control signals from the PLC connect
to the contactor coils through the enable relay contacts. Power section has an enable
relay, which all are in parallel downstream of the common FPO switch.
In addition to the interlockings on the hardware side, the software prevents inverter
operation, if the Fast Power Off switch is pushed.
Startup after FPO
The startup procedure:
1. Before startup, the FPO switch must be released.
2. Reset the fault, the inverter restarts when all other reconnection conditions are
fulfilled.
a) Cable shield
b) Grounding wire
c) Shielded twisted pair
d) Copper foil
a
b
c
d
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