REV 0, June 2005 Page 219
Operation Manual SUPREMA
10. Redundant Systems
10. Redundant Systems
10.1 Application/Function Safety
For the safety functions of gas warning measuring instruments, the European standards EN
50 054–058, EN 61 779 part 1-5, EN 50 104 and EN 50 271 have been prepared for the monitoring
of explosive gas and vapours as well as oxygen.
Additionally, if systems are operated together with microcomputers, the standard EN 61 508
must be considered with regard to functional safety in a measuring and control application.
This standard divides the application types into Safety Integrity Levels SIL 1–4. The system
must be designed to meet the safety level required.
For the EN 61 508 SIL 3 Safety Level, the SUPREMA must be operated with
redundancy. Moreover, the system as well as the MRC-TS module must not be
operated with a redundancy whose failure rate is more than 6.73
*
10
-6
1/h.
For operation according to SIL 4, additional conditions must be met which are not planned for
the SUPREMA for the time being.
By retrofitting modules, a non-redundant rack system can be converted to a redundant system.
There are sufficient spare slots in the rack for the additional MGO modules but not for additional
relay modules, (MTO, MRC).
The following module types are needed for retrofitting:
MCP Module Central Processing
MDA Module Data Acqusition
MAR Module Analog Redundant
MGO Module General Output
MRO-8 Module Relay Output (8 Relay)
MRO-16 Module Relay Output (2 x 8 Relay, redundant)
By adding the MCP Module, operation of a second CAN bus for data acquisition and alarming
as well as the necessary double modules for data acquisisiton and alarming, the non-redun-
dant system can be converted to a redundant system.
10.2 Function of Redundant Systems
The circuit diagram of the redundant system shows its design and function: The signal from
the sensors connected to the MAT modules is amplified by the sensor modules (MCI, MPI) to
give a voltage of approx. 400 ... 2000 mV. By 2 separate A/D converters (on MAI + MAR), the
measuring signal is digitised and transferred to the two processing channels A and B by pas-
sing it through the MDA modules (A + B) to the separate CAN Bus systems (channels). The
signal processing and evaluation of one channel is carried out independently from the other.
The Table 1-1 “Modules of the Rack” shows the different components of the rack for a non-
redundant and a redundant system.
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