Central Unit And Remote Unit Cabling; Power Supply; Inputs/Outputs Cabling; Output Protection - ABB AC 31 Technical Manual

2. Central unit and remote unit cabling

2.1. Power supply

2.2. Inputs/outputs cabling

2.3. Output protection

ABB Control - AC 31
1SBC 260400 R1001-b 06.99
Installation
Use rigid or multi-conductor AWG 14 (1.95 mm
The connection of an external thermal fuse is necessary to provides material protection.
It is possible to select 230 V a.c. or 120 V a.c. with the selector switch situated underneath the
central units or extensible remote units. The products are delivered with the selector in the
230 V a.c. position.
An internal 24 V d.c. power supply is available on 120 / 230 V a.c. versions. This power supply
feeds the binary inputs of the unit and its extensions This internal power supply is protected
against short circuits and overloads. In the case of a short circuit or overload it is available 10
seconds after the fault elimination.
It is also possible to use an external 24 V d.c. power supply. In this case do not forget to
connect the earth of the external 24 V d.c. to that common to the inputs (terminal C).
Use rigid or multi-conductor AWG 18 (0.96 mm
the rigid or multi-conductor AWG 14 (1.95 mm
- Input cabling: see Figure 4-12 to Figure 4-15. The common C of inputs has to be linked
to the 0 V or 24 V d.c. according to the sensor type.
- Output cabling: see Figure 4-16 and Figure 4-17.
The relay outputs may be protected externally against parasites generated by an inductive
load with:
- a varistor or an RC module, in alternating current
- a free-wheel diode, in direct current
The presence of an external thermal fuse, connected to the common power supply of the
outputs, protects to the output connected devices.
The transistor outputs are protected internally against short circuits and overloads. However
with an inductive load, with L/R greater than 40 ms, it is necessary to add a free-wheel diode.
If an error occurs at one of the transistor outputs, it is indicated by the status of the central unit.
The presence of an external thermal fuse, connected to the common power supply of the
outputs, protects the output connected devices and also avoids unit damage should numerous
outputs overload.
Warning: In the case of the terminal O V is disconnected and in the same time the 24 V d.c. is
connected, the leakage current on output is 16 mA.
2
) wires.
2
) to AWG 14 (1.95 mm
2
) wires for the outputs.
2
) wires for inputs and
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