2TLA020070R1700 ABB

General
Pluto is a programmable safety system intended for safety applications where it is not accepted
that faults in the control system lead to loss of a safety function. To achieve this requirement
the system is designed with integral redundancy and monitoring. Unlike ordinary PLC systems,
Pluto utilizes two microprocessors, which both control and monitor each safety function for
correct operation. Each input to the system is separately connected to each processor, each
having their own memory and executing their own program. The processors continuously
compare the results with each other to ensure integrity of data.
Each safety output is connected to both processors and cannot be set unless both have
checked that the logic conditions in the application program are fulfilled.
Each Pluto unit has connections for CAN-bus and can be interconnected with other Pluto units.
The degree of safety is the same over the bus as it is within each unit.
Pluto is designed for fulfilling the demands of the EU Machinery Directive (2006/42/EC)
regarding safety of control systems, however the system can be used in other applications
such as processing industry, furnaces, railways, etc. which have similar requirements.
Pluto is designed according to the following functional safety standards for control systems:
- EN 954-1, Category 4
- EN 62061, SIL3
- EN 13849-1, Category 4 and Performance level e
- IEC 61508-, SIL 3
- IEC-EN 61511-, SIL 3
- EN 50156-1
For an application to fulfil any of the standards above it is necessary that the design and
installation of the complete safety related system (not only Pluto) including sensors and
actuators fulfils the requirements.
Enclosure
Pluto is constructed in an enclosure for snap mounting on
a DIN-rail in control cabinets or other suitable enclosures.
External wiring is connected via screw terminals. To make
it easy and to avoid incorrect connection when a unit is
exchanged, the connector blocks are detachable so that
individual wires do not have to be disconnected.
Note that the power shall be off during connection and
disconnection.
3 Electrical installation
The system is powered by 24V DC. The system has internal overcurrent protection but should
be protected by an external fuse. (See technical data).
In installations with several Pluto units connected together via bus, they must be installed in the
same earthing system. Proper potential equalization is necessary.
The Pluto is designed for applications which fulfil IEC-EN 60204-1 and with special attention to:
- “Transformers shall be used for supplying the control circuits”.
- “Where several transformers are used, it is recommended that the windings of those
transformers be connected in such a manner that the secondary voltages are in phase”.
(see EN 60204-1, 9.1.1)
These requirements are relevant for connection of the relay outputs.
- For electrical safety reasons and in order to be able to detect safety critical earth faults in
single channel circuits, the 0V terminal must be connected to protective bonding circuit.
(see EN 60 204-1, 9.4.3.1 Method a).